An energy audit can discover lots of heat escaping through a home’s attic and walls. However, a new approach to air sealing and insulation can make a big difference.

To build a better thermal envelope, we need to look at the second law of thermodynamics. This law states that heat flows in one direction, from a warm space to a cold one. For example, warm air inside a home will flow to the cooler air outside during winter months. Fiberglass batt insulation helps prevent this from happening, but there’s a better method for preventing heat loss — one that is easy to install and is within your budget.

The best practice for insulating is to use spray foam insulation to fill the spaces between the framing studs in the walls and attic. Spray foam insulation is nontoxic and typically has a lifetime guarantee. It expands to about 100 times its original volume, so it fills in air gaps unlike standard fiberglass insulation. Over time, as the house expands and contracts, so will the foam insulation. This eliminates cracks and spaces for warm air to escape.

If you’re insulating a small part of a wall or several small spaces, you’re probably better off buying your own tanks of spray foam from a local contractor. However, for areas larger than 200 square feet, such as an attic, you should consider hiring a professional. It’s cheaper for you, and they’ll have the equipment for such a large-scale job.

Here’s how to insulate a large space with spray foam insulation:

• Do a test spray. Remember, this material expands to about 100 times its initial volume, so use it conservatively.
• Spray evenly between the studs and on the backside of the exterior sheathing. Allow it to expand so it fills all the gaps.
• After allowing the foam to form and set, take a handsaw blade and shave away any foam that extends past the studs. The foam needs to be flush so that it won’t be an obstacle when you’re ready to install the drywall.

The most common insulation method is to use fiberglass insulation batts, which are placed between the studs and stapled into place. The drywall is then nailed over it, creating a straight wall. Although this is an acceptable method, it does not create an airtight seal, so heat can escape. The amount of heat that escapes from the average home every day could fill up a blimp. By using the better practice of spray foam insulation in walls and attics, you can create a better air-tight envelope. This gives an advantage over common batt insulation in both efficiency and cost.

With foamed-in-place insulation, it is relatively easy (though not inexpensive) to fill wall and ceiling cavities completely. Closed-cell spray foam provides a higher R-value per inch (6.5) than less expensive insulation types like cellulose and fiberglass (3.5 to 3.7).

Most spray polyurethane foam is called “two-component” foam. Two ingredients—conventionally called “A” and “B” components—are mixed on site using special equipment mounted in a trailer or truck. Heated hoses convey the components to a mixing gun that sprays the chemicals on the surfaces to be insulated.

A chemical reaction begins as soon as the chemicals are mixed. The liquid mixture foams, expands, and eventually hardens.

Choose a conscientious installer

Most jobs are for pros
Spray polyurethane foam is usually installed by a spray-foam contractor equipped with a truck or trailer to carry the necessary chemicals and spray equipment.

For smaller jobs, builders can purchase disposable tanks of two-component polyurethane foam. These tanks are sold in various sizes, and range in cost from about $200 to $500. For very small jobs, small aerosol cans of one-component (moisture-cured) polyurethane foam can be purchased at most building-supply stores for about $5 a can.

Experience matters
Although spray polyurethane foam has many advantages over other types of insulation, spray foam installation isn’t foolproof. Some builders have reported problems with sloppy foam insulation. For example, some installers have been known to begin spraying before the chemical components are up to temperature, which can affect component mixing and foam performance. When components are poorly mixed, or mixed in the wrong ratio or at the wrong temperature, cured foam has been known to shrink away from rafters or studs, leaving cracks. Some installers rush through their spraying, resulting in voids.

As with any type of insulation—whether fiberglass batts, cellulose, or spray foam—it’s important to choose an installer with a good reputation; to monitor the installer’s work; and to verify that the insulation work meets expectations before making the final payment on the job.

Find a certified spray foam contractor

BASF announced today (October 5, 2011) that closed-cell spray polyurethane foam products have received hurricane-zone approval from the Miami-Dade County Building and Neighborhood Compliance (BNC) Department. Tests and engineering evaluations of COMFORT FOAM® and SPRAYTITE® (178 series) applied at roofing trusses increased the wind-uplift resistance of a traditional code-approved home roof by more than 200 percent. Spray Polyurethane Foam (SPF) from BASF can enhance wind-uplift resistance of new and existing homes to help prevent roof failure during a hurricane.*

Submission of this test data to the Miami-Dade County BNC office resulted in the first Notice of Acceptance (NOA)** for this application with approval for use in High Velocity Hurricane Zones.

“This new hurricane-zone approval adds high-wind mitigation to an already impressive list of product benefits,” said Michael Sievers, Business Manager, Spray Systems, BASF. Sievers added that this specialty application must be installed by a BASF qualified contractor.

The Miami-Dade County NOA indicates that when BASF spray foam is applied as a three-inch fillet along the truss and roof deck, it glues the roof down to provide a simple and cost-effective means of significantly strengthening the roof against failure during high-wind events. BASF also has Florida Building Code (FBC) product approval (FL #13001) for COMFORT FOAM and SPRAYTITE (178 series) SPF products. Adding a total of three inches of closed-cell spray foam under the roof deck will also give the homeowner energy savings and wind resistance. Reduced homeowner insurance premiums may also be an added financial incentive in some areas of the country.

Homeowners in high-wind areas who want to maximize the benefits of COMFORT FOAM, including: premium-insulating values, improved indoor air quality, reduced energy bills and stronger roofs, are recommended to install a three-inch continuous application to the entire roof deck.

What stands tall after the storm may depend on a strong roof
The National Oceanic and Atmospheric Administration (NOAA) reports that hurricanes account for average insured losses of about 5.2 billion dollars per year in the United States. The majority of these losses were directly caused by severe wind and rain exposure resulting from a failed roof deck, according to a study by Clemson University.

BASF understands the value of providing materials that protect homes during catastrophic weather events including storms, hurricanes and high winds. Particularly vulnerable to these conditions are roofs. According to the Federal Alliance for Safe Homes, if a roof is not properly secured to the rest of a home, the likelihood of structural failure is much greater than if reinforced with hurricane damage mitigation tools.*** This type of application of spray foam glues the roof sheathing to the rafters, giving severe wind and rain no room to enter and weaken a structure.

For more information on the energy and structural benefits of building or retrofitting your home with BASF spray foam insulation, please visit http://www.spf.basf.com.

About BASF Polyurethanes
BASF is the leading supplier of Polyurethane Solutions for systems, specialties and PU basic products. With its global network of 38 polyurethane system houses and its comprehensive product and service portfolio, BASF is the preferred partner of its customers in many industries.

The BASF brand “Polyurethane Solutions” represents over 40 years of experience of the market and technology leadership for Polyurethane Systems.

In the extremely service-oriented business of polyurethane systems and specialties, reliable PU experience and competence are crucial. Through its system house network, BASF provides fast local support, from technical service and sales to production and marketing during the development of customized solutions. With its world-scale plants, BASF secures its leading market position in the production of polyurethane basic products in all regions of the world.

Polyurethanes make life more comfortable, safer and more pleasant while helping to save energy sustainably. They contribute towards improved insulation of buildings and more attractive, lightweight design of cars. Producers of shoes, mattresses and household goods as well as sports equipment use the unique advantages of polyurethanes provided with the knowledge and expertise of the polyurethane experts of BASF world-wide. Further information is available on the internet at http://www.polyurethanes.basf.com.

When you buy a new house, before it’s built, you get to choose from the variety of styles and floor plans the builder offers, as well as options and upgrades on details and finishes. Depending on the builder, sometimes the options and choices of upgrades are very limited. Most times, those options are limited to finishes. Rarely do they offer green upgrades, or upgrades on what matters most: what’s behind the walls.

A lot of builders and building companies have model homes, or even a design centre you can visit to help you decide on the finishes and upgrades you might want to add. What’s on display is always finishes. It’s never the insulation, the drywall or tile underlayment. You’ll never see air purifiers on display or added as an extra appliance.

Energy Star appliances are standard now with new homes, and they are built to minimum code standards with regard to construction, building envelope, insulation.

But what about green upgrades?

Some leading green builders offer features such as solar rooftop photovoltaic (PV) and solar hot-water pre-heating rough-ins for those who want that option. And lots are coming on board with low/no VOC paints, and maybe some bamboo flooring. But that’s about it, I’m sad to say.

That’s all driven by consumer demand. Builders will build what sells, so it’s up to you to demand upgrades that will really increase the value of your home.

What do homebuyers think is important when they invest in their new homes?

Everyone is concerned about indoor air quality, and the effects of mould and allergens on their families’ health. But how many people are even aware of the upgrades they can have that will improve that indoor air quality? The type of insulation you choose, the type of cabinets and flooring, all contribute to the indoor air quality. What about adding an air-purifying system or premium HEPA filtration to your HVAC?

Some people will advise you to choose your upgrades based on future resale of your home. That’s fine, but who’s to say a brushed nickel faucet will still be fashionable when your home goes on the market? Will cherry cabinets be in, or will painted wood? Is your money better spent on a granite countertop or on a properly insulated basement and attic?

A finished basement is a popular one. But for me, this is one of the real traps of a “builder upgrade.” Guaranteed: If you opt for this upgrade, you will have a basement finished to minimum code. That’s all that’s required. And that will be a complete waste of your money — in either a short time or a slightly longer time — when you need to tear everything out because it’s tainted with mould.

Conventional wisdom says that spending your upgrade money on kitchen and bathrooms will repay you. But I say that every penny you invest in an upgrade that improves your home’s efficiency will repay you, too.

I say, when your budget is limited — and whose isn’t? — spend your upgrade money on the places you can’t get to later: behind the walls. You can always upgrade a standard finish to something pricier later, if you want to. But you can’t easily change your insulation or the underlayment beneath your tiles or replace your standard drywall with mould-resistant.

The consumer decisions always seem to be: Do you want the premium kitchen cabinets or the standard? Do you want a granite countertop or laminate? What kind of tile do you want in the bathroom?

People spend hours discussing choices of light fixtures, door handles, cabinet hardware, plumbing fixtures, paint colour, crown moulding and style of baseboards. Who cares? Seriously.

What about the level of insulation — code or above code? What kind of insulation — blown-in cellulose, batt, or spray foam? How good are the windows?Are they high-performance? BluWood or standard? Mould-resistant drywall or standard?

Can you choose sustainably sourced hardwood for your flooring?

Ask the questions. Make the right choices on your upgrades.

Homeowners can quickly search for spray foam contractors in their state, through our convenient search engine.  Search results can rapidly be scanned for areas of special interest with the certification icons.  Each potential contractor can be contacted directly for a custom estimate and/or reference checks.

Homeowners looking to save money on their long-term energy bills will find the Spray Foam Homes site extremely useful with tips and best practices for reducing energy consumption.  The combination of spray foam insulation and practical advice will save homeowners tremendous amounts of money year after year.

Our mission is to provide homeowners, as well as builders, GC’s, architects and all other energy-conscious individuals with the most current news and information on spray polyurethane foam technology.

We invite your commentary, thoughts, and suggestions for topics.  In fact, if you’d like to submit an article for publication on the Spray Foam Homes site(s), please email it to us.  All submissions are welcome!

This PDF article discusses the advantageous and differences between open-cell and closed-cell spray polyurethane foam.

As a result, the upcoming 2006 edition of IRC will allow unvented, conditioned attics when the following four conditions are met:

1. No interior vapor retarders are installed on the ceiling side (attic floor) of the unvented attic space.

2. An air-impermeable insulation is applied directly to the interior underside of the structural roof deck. “Air permeable” is defined as ASTM E283, “Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen.” An exception is permitted in the code’s Climate Zones 2B and 3B (portions of southern California and Arizona) where the use of air-impermeable insulation is not required.

3. In Climate Zones 3 through 8, sufficient insulation is installed to maintain the monthly average temperature of the condensing surface above 45 F (7 C). These zones encompass all the U.S. except Florida and Hawaii and the southernmost portions of Alabama, Arizona, California, Georgia, Louisiana, Mississippi and Texas. The condensing surface is defined as either the structural roof deck or interior surface side of the air-impermeable insulation. For calculation purposes, an interior design temperature of 68 F (20 C) is assumed; exterior temperature is determined as the monthly average outside temperature.

4. In warm, humid locations, for asphalt shingle roof systems, a vapor retarder with a perm rating of 1 perm (57.4 mg/s•m²•Pa) or less be installed on the exterior side of the structural roof deck. For wood shingle and shake roof systems, a 1/4-inch- (6-mm-) thick minimum air space shall be provided between the underlayment and shingles or shakes. “Warm, humid locations” include all of Florida and specific counties in Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Texas.

UNVENTED ATTIC:

The new International Residential Code language allows unvented attic spaces, as long as the roof is insulated with air-impermeable foam and there’s no vapor retarder between the attic and the living space.

Recommended insulation for coastal areas by FEMA technical fact sheet # 8 Insulation: plastics, synthetics, and closed-cell foam, or other types approved by local building officials

There’s no evidence that sealed and insulated attics trap moisture. Researchers have found that, in hot, humid climates, buildings with unvented attics are actually less likely to have condensation and mold than those with vented attics. That’s because, in these climates, most moisture comes from outside, and the foam keeps the attic dry by sealing that moisture out.

Humid attics wouldn’t be so bad if it weren’t for leaky air-conditioning ducts. Depending on the pressures in the HVAC system and the pressures in the house created by that system, these leaks can blow cold air into the attic or suck hot, humid air into the ductwork and into floor and wall cavities. Either way, you have a problem. Air leaking from the ducts can cool nearby surfaces enough that humid attic air condenses on them. Moist air pulled into the ductwork will get blown into the living space, where it can condense on walls and ceilings. There has seen none of these ills in homes with sealed and conditioned attics (conditioned by means of passive connection to the living space).

Foam contractors are trained and certified by insulation manufacturers. There have been no reported problems with unvented attics built in Florida as long as 10 years ago. It’s a proven building technology.

In high wind regions – particularly in coastal areas, wind driven rain is a problem with vented roof assemblies. Additionally, during high wind events, vented soffit collapse leads to building pressurization and window blowout and roof loss due to increased uplift. Unvented roofs – principally due to the robustness of their soffit construction – outperform vented roofs during hurricanes – they are safer.

Effects on roofing

• The greatest influence on roof temperature is geographic location. The mean roof temperatures for Miami and Green Bay, Wis., for example, differ by 18 degrees Celsius.
• The direction a roof faces has the second greatest influence on average roof temperature (in excess of 1.44 degrees Celsius in the east through south-to-west range studied, but the real difference is greater because other directions, such as north, will be cooler).
• The color of roofing materials influences the mean temperature of a roof system slightly less than direction (1.45 degrees Celsius average for these parameters).
• Ventilating the area under a roof deck reduces the average temperature 0.5 degrees Celsius (about one-third the influence of the direction or color and one-thirty-sixth the influence of geographic location). Even with wind assistance, ventilation reduces average roof temperature about half as much as using white rather than black shingles.
• Within the ranges studied, slope has the least influence on average shingle temperature

Expanding spray-in-place foam insulation products such as those based on a polyurethane formulation have several beneficial aspects over other forms of insulation. Spray foam insulation currently costs more than alternative insulation products, but this additional upfront cost can be overcome when the other benefits of spray foam are utilized and realized. These aspects include benefits associated with increased structural/strength properties, enhanced thermal insulation capabilities, and reduced air infiltration properties.

Structural benefits: Clemson University has been researching the use of spray foam as an enhanced attachment system for roofing. This research centers on how to retrofit or construct buildings to be more resistant to hurricane and other high wind events. Clemson’s research shows that spray foam can significantly improve the attachment of roof sheathing to trusses and rafters, similar to the way construction adhesives help bond a floor system together. In a retrofit case, foam can be sprayed on one or both sides of the sheathing/rafter intersection from inside the finished roof. In new construction, spray foam can be applied to the entire roof system. The spray foam makes a significantly stronger roof than either nails or screws alone. More information on this research is available from Clemson University’s Civil Engineering Department, or the 113 Calhoun St Project in Charleston, SC.

Thermal and air benefits: A second aspect of spray foam is the enhanced thermal insulation characteristics. The stated R-value, or thermal resistance value, of insulation is measured under laboratory conditions. Real-life in-use R-values are quite different. An R-13 rated insulation batt installed improperly may only provide R-9. Whole wall Rvalues may be even less because of voids, wood, headers, etc. in the wall. Spray foam can provide a higher whole-wall R-value because of its ability to better fill wall cavities around electrical, plumbing, and other obstructions within the wall. The Oak Ridge National Lab has tested several whole-wall R-values for various wall/insulation combinations. Some of their results have been published in publications such as Energy Design Update, and should be available on their web site soon.

The R-value of an insulation system also depends upon the lack of air movement through the insulation. Most insulation products use entrapped air as a barrier to heat transfer. Therefore, to get a high R-value, air cannot move within or through the insulation.

In a whole-house situation, part of the energy use is in infiltration air. Air flow retarder products such as house wraps were developed to reduce the amount of infiltration air. These air barriers help reduce infiltration as well as air movement through the insulation.

Typical loose fill or batt insulation works well if installed correctly, and if installed in conjunction with an air barrier. Good installation is difficult to do, however. The insulation is often packed too tight or too loose, cut too short or too long, gapped around plumbing and wiring, or left out because of access problems.

Spray foams claim a couple benefits. First, they fill gaps and voids better. Second, they perform well as air flow retarders. The result is a higher in-the-wall R-value. Infiltration is also reduced, so that component of a building’s energy use is reduced. Both of these benefits result in raising the “effective” R-value of spray foam when compared to typically installed loose fill or batt insulation.

Spray foam products must still be sprayed correctly, and dense-pack blown cellulose can make some of the same claims. Spray foam is also self-supporting, which enables its use on the underside of roofs and floors.

Roof Benefits: Insulating the underside of a roof rather than a ceiling creates many other benefits as well. Historically, we ventilated roofs in an attempt to prevent moisture problems and reduce heat build-up.

Current research shows that much of the moisture in attics comes from damp basements or crawl spaces, as well as from the living space. Research also shows that if we address crawl space, basement, attic and living space moisture, we do not need to ventilate an attic. In fact, by ventilating an attic, we can often make a moisture problem worse.

Attic moisture problems are a result of moisture condensing on cold roof surfaces. Adding more vents causes the attic to be cooler, especially at night, which causes more condensation to form on the underside of the cold roof. Cutting a hole in the roof causes a bigger hole in the top of our “chimney”, which makes the “chimney” draw better, pulling even more moisture upward. I have not seen any attic moisture problems solved by adding attic ventilation, with the exception of ice damming. (Ice damming is a “warm” attic phenomenon, and can better be addressed by reducing the amount of heat leaking into the attic.) Unfortunately, the building codes haven’t kept up.

Ventilation to reduce summer heat build up in an attic has also been challenged recently by research done at the Florida Solar Research Center and the Building Research Council in Illinois. Much of the heat in an attic is from radiant heat transfer. The hot sheathing radiates heat to the ceiling or other objects in the attic. To cool an attic, outside air is vented through attic or insulation is added to the ceiling to prevent the attic heat from warming the living space. Research has shown that the ventilation rate would have to be quite large to make much difference in an attic temperature. In the summer, the best you could possibly achieve was outside temperature. With a very large fan using lots of energy, you might get close to outside temperatures. In winter, this would result in a colder attic as well.

Ceilings are usually insulated because of the ease of piling up cheap insulation. Recessed lights, outside walls, sloped or tray ceilings and knee walls all create a non-uniform thermal “cap” on the building and result in voids in the insulation. The real-life R-value of an insulated ceiling is very often less than the claimed R-value.

Ducts are often located in the attic, which exposes the coolest/warmest air in the house to the hottest/coldest environment in the house (depending upon the season). This does not create a very energy efficient situation. As much as 10% of the heat or AC can be lost by placing ducts in an unconditioned attic.

From an energy standpoint, ducts and air handlers should be located within the conditioned space. This reduces heat transfer to the outside, and reduces some concern of duct leakage. Recently, building researchers proposed making crawl spaces into unvented, conditioned plenums, which is now accepted by code. More recently, building researchers proposed making attics into conditioned space by eliminating ventilation and insulating the underside of the roof rather than the ceiling. As a building researcher, I fully support both concepts.

A roof system insulated with spray foam reduces energy several ways. Energy loss from ducts located in the attic is essentially eliminated. The top of the building is much tighter resulting in less infiltration and exfiltration, so excess moisture isn’t pulled into the attic. Infiltration through the ceiling is also reduced. In addition, the attic temperature is lower, which further reduces energy loads.

In a standard insulation system, ceiling insulation reduces the transfer of heat from the attic to the living space (in the summer). Attic temperatures can often approach 140F during the day. Most of this heat enters the attic space through a multi-step process. First, solar energy warms the shingles and sheathing. The hot sheathing then transfers heat to the rest of the attic through conduction, convection and radiant heat transfer. The 140F temperature of the underside roof surface drives the heat transfer process

By insulating the roof surface with spray foam, the surface temperature exposed to the attic (the temperature driving the heat transfer) is reduced by as much as 40F. Both conduction and convection heat transfer are proportional to a temperature difference, so that heat transfer will be reduced proportional to a drop in surface temperature. Radiant heat transfer, though, is proportional the 4th power of the temperature difference. The reduction in radiant heat transfer resulting from an insulated roof can easily exceed conduction and convection reductions.

The benefits of including the attic in the insulated space are:

• Duct leakage and heat loss/gain from ducts is much less of an issue.
• Air sealing is easier in the roof that in the ceiling.
• Dust and loose insulation are less likely to migrate down to the living space.
• Tests show energy costs are lower when the attic is sealed.

Further information is available from ASHRAE (8700-527-4723) in a publication titled “Vented and Sealed Attics in Hot Climates”.

Crawl Spaces Benefits: Batt insulation is usually installed between the floor joists over a crawl space foundation. Problems associated with this installation technique include incomplete thermal barriers from obstructions such as wiring and plumbing, ductwork, and narrow or wide joist spacing. Batts are often compressed during installation due to the use of wire insulation hangers. Open web floor trusses create additional problems in that the open webs create pathways for air to move around the batts. During the summer, warm humid air can flow around the batts and create condensation, mold and decay problems in the floor system. In my opinion, open web floor trusses are impossible to adequately insulate with batts.

Spray foam circumvents floor insulation problems through its ability to completely fill voids and open spaces. Areas around wiring and plumbing as well as open webs of floor trusses can be completely filled, resulting in a complete, essentially uniform thermal barrier on the floor. Spray foam will also create an effective air flow retarder layer on the floor, which will reduce the house air by crawl space air.

In my opinion, spray foam insulation is a superior insulation product that overcomes several disadvantages of other insulation products. Spray foam can provide a more uniform, consistent thermal barrier as well as provide air flow retarder functions. To best obtain spray foam’s potential benefits, and overcome it’s higher initial costs, spray foam should be used in a systems approach to creating a better building. In a roof application, spray foam will increase the structure’s ability to handle high winds as well as bring the attic into the conditioned space. A roof application of spray foam will reduce infiltration and reduce ceiling heat transfer and duct losses. Wall and floor applications will also create better thermal and air barriers, and make better use of engineered products. Spray foam insulation can result in less conductive, convective and radiant heat transfer, lower infiltration rates, less duct losses, a more structurally sound building and can result in significantly smaller-sized heating and cooling systems and better comfort levels for the occupants.

It is impossible to define an insulation with a single number. It is imperative we know more than a single “R” number. So why do we allow the R-value fairy tale to be perpetuated? I don’t know. I don’t know if anybody knows. It obviously favors fiber insulation. Consider the R-value of an insulation after it has been submersed in water or with a 20 mile per hour wind blowing through it. Obviously the R-value of fiber insulations would go to zero. Under the same conditions, the solid insulations would be largely unaffected. Again R-value numbers are “funny” numbers. They are meaningless unless we know other characteristics.

None of us would ever buy a piece of property if we knew only one dimension. Suppose someone offered a property for $10,000 and told you it was a seven. You would instantly wonder if that meant seven acres, seven square feet, seven miles square, or what. You would want to know where it was — in a swamp, on a mountain, in downtown Dallas. In other words, one number cannot accurately describe anything. The use of an R-value alone is absolutely ridiculous. Yet we have Code bodies mandating R-values of 20′s or 30′s or 40′s. A fiber insulation having an R-value of 25 placed in a house not properly sealed will allow the wind to blow through it as if there were no insulation. Maybe the R-value is accurate in the tested material in the lab, but it is not even remotely part of the real world. We must start asking for some additional dimensions to our insulation. We need to know its resistance to air penetration, to free water, and to vapor drive. What is the R-value after it is subjected to real world conditions?

The R-value is a fictitious number supposed to indicate a material’s ability to resist heat loss. It is derived by taking the “k” value of a product and dividing it into the number one. The “k” value is the actual measurement of heat transferred through a specific material.

Test to Determine the R-Value

The test used to produce the “k” value is an ASTM test. This ASTM test was designed by a committee to give us measurement values that hopefully would be meaningful. A major part of the problem lies in the design of the test. The test favors the fiber insulations — fiberglass, rock wool, and cellulose fiber. Very little input went into the test for the solid insulations, such as foam glass, cork, expanded polystyrene or urethane foam.

The test does not account for air movement (wind) or any amount of moisture (water vapor). In other words, the test used to create the R-value is a test in non-real-world conditions. For instance, fiberglass is generally assigned an R-value of approximately 3.5. It will only achieve that R-value if tested in an absolute zero wind and zero moisture environment. Zero wind and zero moisture are not real-world. Our houses leak air, all our buildings leak air, and they often leak water. Water vapor from the atmosphere, showers, cooking, breathing, etc. constantly moves back and forth through the walls and ceilings. If an attic is not properly ventilated, the water vapor from inside a house will very quickly semi-saturate the insulation above the ceiling. Even small amounts of moisture will cause a dramatic drop in fiber insulation’s R-value — as much as 50 percent or more.

Vapor Barriers

We are told, with very good reason, that insulation should have a vapor barrier on the warm side. Which is the warm side of the wall of a house? Obviously, it changes from summer to winter — even from day to night. If it is 20 F below zero outside, the inside of an occupied house is certainly the warm side. During the summer months, when the sun is shining, very obviously the warm side is the outside. Sometimes the novice will try to put vapor barriers on both sides of the insulation. Vapor barriers on both sides of fiber insulation generally prove to be disastrous. It seems the vapor barriers will stop most of the moisture but not all. Small amounts of moisture will move into the fiber insulation between the two vapor barriers and be trapped. It will accumulate as the temperature swings back and forth. This accumulation can become a huge problem. We have re-insulated a number of potato storage’s which originally were insulated with fiberglass having a vapor barrier on both sides. Within a year or two the insulation would completely fail to insulate. The moisture would get trapped between the vapor barriers and saturate the fiberglass insulation to the point of holding buckets of water. Fiber insulation needs ventilation on one side; therefore, the vapor barrier should go on the side where it will do the most good.

We understand air penetration through the wall of the house. In some homes when the wind blows, we often can feel it. But what most people, including many engineers, do not realize is that there are very serious convection currents that occur within the fiber insulations. These convection currents rotate vast amounts of air. The air currents are not fast enough to feel or even measure with any but the most sensitive instruments. Nevertheless, the air is constantly carrying heat from the underside of the pile of fibers to the top side, letting it escape. If we seal off the air movement, we generally seal in water vapor. The additional water often will condense (this now becomes a source of water for rotting of the structure). The water, as a vapor or condensation, will seriously decrease the insulation value — the R-value. The only way to deal with a fiber insulation is to ventilate. But to ventilate means moving air which also decreases the R-value.

Air Penetration

The filter medium for most furnace filters is fiberglass — the same spun fiberglass used as insulation. Fiberglass is used for an air filter because it has less impedance to the air flow, and it is cheap. In other words, the air flows through it very readily. It is ironic how we wrap our house in a furnace filter that will strain the bugs out of the wind as it blows through the house. There are tremendous air currents that blow through the walls of a typical home. As a demonstration, hold a lit candle near an electrical outlet on an outside wall when the wind is blowing. The average home with all its doors and windows closed has a combination of air leaks equal to the size of an open door. Even if we do a perfect job of installing the fiber insulation in our house and bring the air infiltration very close to zero from one side of the wall to the other, we still do not stop the air from moving through the insulation itself vertically both in the ceiling and the walls.

The best known solid insulation is expanded polystyrene. Other solid insulations include cork, foam glass and polyisocyanate or polyisocyanurate board stock. The latter two being variations of urethane foam. Each of these insulations are ideally suited for many uses. Foam glass has been used for years on hot and cold tanks, especially in places where vapor drive is a problem. Cork is of course a very old standby often used in freezer applications. EPS or expanded polystyrene is seemingly used everywhere from throw away drinking cups and food containers to perimeter foundation insulation, masonry insulations, and more. Urethane board stock is becoming the standard for roof insulation, especially for hot mopped roofs. It is also widely used for exterior sheathing on many of the new houses. The R-value of the urethane board stock is of course better than any of the other solid insulations. All of the solid insulations will perform far better than fiber insulations whenever there is wind or moisture involved.

Most of the solid insulations are placed as sheets or board stock. They suffer from one very common problem. They generally don’t fit tight enough to prevent air infiltration. It does not matters how thick these board stocks are if the wind gets behind it. We see this often in masonry construction where board stock is used between a brick and a block wall. Unless the board stock is actually physically glued to the block wall air will infiltrate behind it. In this case as the air flows through the weep holes in the brick and around the insulation it is rendered virtually useless. Great care must be exercised in placing the solid insulations. The brick ties need to be fitted at the joints and then sealed to prevent air flow behind the insulation.

The only commonly used solid insulation that absolutely protects itself from air infiltration is the spray-in-place polyurethane. When it is properly placed between two studs or against the concrete block wall or wherever, the bonding of the spray plus the expansion of the material in place will effect a total seal. This total seal is almost impossible to overestimate. In my opinion most of the heat loss in the walls of the home have to do with the seal rather than the insulation.

For physical reasons, heat does not conduct horizontally nearly as well as it does vertically. Therefore, if there were no insulation in the walls of the homes, but an absolute airtight seal, there would not necessarily be a huge difference in the heat loss. This would not be the case if the insulation was missing from the ceiling. Air infiltration can most effectively be stopped with spray-in-place polyurethane. It is the only material (properly applied) that will fill in the corners, the cripples, the double studs, bottom plates, top plates, etc. The R-value of a material is of no interest or consequence if air can get past it.

Anecdotes

During the 1970s my firm insulated a bunch of new homes in the Snake River Valley of Idaho with 1.25 inches of spray-in-place polyurethane foam in the walls. In 1970 the popular number for the R-value of one inch of urethane foam was 9.09 per inch. Using this value, we were putting an R of 1.25 x 9.09 = 11.36 in the walls. This was much less than the R = 16 claimed by the fiberglass insulators. Today, using the charts from an ASHRAE book, we would only be able to claim an R-value for the 1.25 inches of 7.5 to 9. Neither of these numbers make for a very big R-value. The reality is that the people for whom we insulated their homes invariably would thank us for the savings in their heat bills. They would tell us their heating bill was half of their neighbor’s. They felt as if they saved the cost of the polyurethane in one, or at most two, years. This is anecdotal evidence, I know, but anecdotal evidence is also compelling and very real in our world. Most of these customers were savvy people. They would not have paid the extra to get the urethane insulation if it had not been better.

About mid 1975 I received a call from a division manager of one of the major fiberglass insulation manufacturers. The caller asked, “I understand that you are spraying polyurethane in the walls of homes?” I told him that was true. He was calling because we were cutting into the fiberglass insulation sales in our area. He asked, “How can you do it?”

I knew what he meant. He wanted to know how I could look somebody in the eye and sell them a more expensive insulation than the cheap old fiberglass. I told him the way I did it is with a spray gun. Of course, that wasn’t the answer he wanted. He wanted to know how I could not feel guilty. I told him of insulating one of two nearly identical houses built side by side. We insulated the walls of one with 1.25 inches of urethane. The other house was insulated with full thick fiberglass batts put in place by a reputable installer. Not only did we use only 1.25 inches of urethane as the total wall insulation, but we had the builder leave off the insulated sheathing. At the end of the first winter, the urethane insulated home had a heating bill half of their neighbor’s. I know that is not terribly scientific, but it is very real. I am not sure he was convinced, but it should be noted that same company jumped into the urethane foam supply business the next year.

One and a quarter inch of polyurethane sprayed properly in the wall of a house will prevent more heat loss than all the fiber insulation that can be crammed in the walls — even up to an eight inch thickness. Not only does it provide better insulation, but it provides significant additional strength to the house.

One of my early clients was Brent. I had insulated several potato storages for Brent. He knew what spray-in-place urethane insulation could do. When he decided to build his new, very large, very fancy new home, he asked me to come insulate it. I told him I would be delighted. The builder pitched a fit. He “didn’t need any of that spray-in-place urethane in his buildings. He made his buildings tight, and fiberglass was just as good.”

Brent explained to the builder, “I know who is going to insulate the building. It is not as definite as to who is going to be the contractor. You can make up your mind. We are going to have the urethane insulation and you build the building, or we are going to have the urethane insulation, and I will have someone else build the building.” It didn’t take the contractor long to decide he wanted to use urethane insulation.

It was amazing to me how it worked out. We sprayed a lot of foam in Brent’s house, and it cost him quite a bit of money because it was such a large home. Always after when I would meet him, he would tell me his heat bill was less than any of his rent houses or homes of anybody else he knew. And his home was two or three times larger. Also, the builder started having me insulate most of his new custom built houses. He told me he would explain to his clients the best insulation was the spray-in-place urethane. It would cost a little more, but it was by far the best. Most of the owners opted for the urethane. Never have I had a customer tell me that he did not save money by using the urethane spray-in-place insulation. You can spend all the time you want with R-values and “k” factors, and “prove” on paper there is no way the urethane can do the insulation job that the fiberglass will. In the real world, I can assure anyone there is no way fiber insulation can be as effective as spray-in-place urethane — not even close.

R-value tables are truly part of the “Fairy Tale.” They show the solid and the fiber insulations side by side, implying they can be compared. The fact is, without taking installation conditions into account, comparisons are meaningless. Spray-in-place urethane foam provides its own vapor barrier, water barrier, and wind barrier. None of the other insulations are as effective without special care taken at installation. The fiber insulations must be protected from wind, water and water vapor. Again the tables need a second table to state installation conditions.

Consider the following anecdotes:

Meadow Gold Company was going to build a freezer in Idaho Falls, Idaho. Chet, the plant manager was a good friend of the local Butler dealer. The local Butler dealer and I had become good friends. A Butler building does not lend itself very well to a freezer if you are going to insulate the freezer with expanded polystyrene. So the three of us got together and planned a freezer that would accommodate the needs of Meadow Gold yet be built of a Butler building and be properly insulated. This was in my first year of spraying polyurethane foam, and at that time I believed all the literature and knew what we were doing was going to be just right. It turned out even better. The then current R-value table showed one inch of urethane equal to 2.5 inches of expanded polystyrene. So, I suggested we spray the metal building with four inches of urethane to replace the 10 inches of expanded polystyrene normally used by Meadow Gold for freezers.

Meadow Gold Company was going to build a freezer in Idaho Falls, Idaho. Chet, the plant manager was a good friend of the local Butler dealer. The local Butler dealer and I had become good friends. A Butler building does not lend itself very well to a freezer if you are going to insulate the freezer with expanded polystyrene. So the three of us got together and planned a freezer that would accommodate the needs of Meadow Gold yet be built of a Butler building and be properly insulated. This was in my first year of spraying polyurethane foam, and at that time I believed all the literature and knew what we were doing was going to be just right. It turned out even better. The then current R-value table showed one inch of urethane equal to 2.5 inches of expanded polystyrene. So, I suggested we spray the metal building with four inches of urethane to replace the 10 inches of expanded polystyrene normally used by Meadow Gold for freezers.

Chet considered one alternative to his predicament was to turn one of the older freezers that had been used as a cooler back into a freezer. Then maybe he could make a cooler out of the new building with the just the one compressor. It was not a satisfactory arrangement, but it maybe could work. The other thing Chet kept telling us was that he would know as soon as he turned on the freezer equipment whether or not the building would work. When I pressed him, he said that normally it takes five days to bring a freezer down to 10 F below zero — needed for ice cream. When he turned on the new freezer, with only the one compressor, the temperature dropped to 18F degrees below zero by the second morning. They had their freezer. It ran the entire summer using only the single compressor.

A few weeks after start up of the freezer, I was visited by a Meadow Gold engineer from Chicago. He wanted to know exactly what we had done to insulate the freezer. One compressor should not be able to hold the temperature as it was doing. I explained to him exactly what we had done. He seemed satisfied and he left. A few weeks later he showed up again with his boss. We went to the plant and verified with an ice pick the thickness of the foam. It was indeed four inches in the walls and five inches in the ceiling. Here again they reiterated that the building should not be operating as it was. What they were telling me was that even though I had used one inch of urethane to replace 2.5 inches of expanded polystyrene, the building was still requiring only 50 percent of the normal compressor power for cooling. As you can imagine, the experience made me a lot more bold, and I used the information to sell more freezer insulation jobs.

One of our largest freezer insulation projects was a sixty thousand square foot freezer at Clearfield, Utah. I was able to talk the general contractor into letting us insulate with spray-in-place polyurethane foam the brand-new all-concrete freezer he was building. This building was the 12th in a chain of freezers. My friend Bob, the contractor, had taken it upon himself to make the switch from the ten inches of expanded polystyrene to four inches of urethane with a fifth inch on the roof. The building was built with tilt up concrete insulated on the interior side of the concrete with spray-in-place urethane. We then sprayed on a three-fourths of an inch thick layer of plaster as the thermal barrier. Over the pre-stressed concrete roof panels, we put five inches of spray-in-place urethane and then covered it with hot tar and rock. (This is an old CPR-specification).

I was on the job the last day. As we finished up the owner showed up. He had expected to see ten inches of expanded polystyrene, and here was four inches of urethane. I told him he would like the four inches of urethane as it would be even better than the expanded polystyrene, based on my previous experience. He told me he was sicker than a dog because he felt like there was no way that could be true. It was too late for him to do anything about it. If he could have, he would have changed the contract instantly, but he was stuck and felt stuck.

They had 12 other similar size freezers, except the others were insulated with expanded polystyrene. The normal way of operating them was to use three large compressor assemblies. Two of the compressors would be needed all summer to keep the building cold, and the third one would be a standby unit, in case one of the other two had problems.

About a year later, I received a phone call from one of the managers. He asked me if I had time to insulate another sixty thousand square foot freezer in Clearfield, Utah. I assured him we had the time, the inclination, and the excitement to do it, but I thought the owner wanted nothing to do with urethane foam insulation. The manager explained to me that not only had the Clearfield freezer operated better than any other freezer in their line, it had operated for less than half the costs of any others. They were adding another sixty thousand square feet without adding more compressors. The compressor power available to them because of the urethane insulation efficiency allowed them to do it. The building had run very nicely through the hot part of the summer with just one compressor. Now they would be able to run two buildings off of two compressors and still have a spare.

Again, this is anecdotal evidence, but let me assure you that you will get the same results if you do the same thing as we have. I have insulated too many buildings now to know that this will happen in every case. Never can you use an R-value from a fiber insulation and compare it to the R-value of a foam insulation. Nor can you use the R-value of a foam insulation if it is in sheet form and compare it to the R-value of the foam insulation if it is spray-in-place. Spray-in-place polyurethane is an absolute minimum of three to ten times as effective as any other insulation available today.

During the late 1970s, the FTC went after the urethane foam suppliers for misleading advertising especially with regard to fire claims. A consent decree followed. It destroyed a tremendous amount of confidence in the use of urethane. Up to that point, Commonwealth Edison would give Gold Medallion approval for homes insulated with 1.25 inches of spray-in-place urethane in the side walls of masonry constructed homes. True, that was anecdotal evidence, but also true, it worked. Much work was done in the early 1970s using a 1.25 inches urethane as a replacement for wall insulation in a home. Not only did it replace the wall insulation, it also replaced the exterior sheathing. The buildings are stronger and better insulated when sprayed with the 1.25 inches of urethane.

Understanding the two purposes of insulation gives a standard to measure the insulations:

I. Heat loss

There is a little understood part about insulation that needs to be covered. There is a substantial difference between insulation for temperature control and insulation for heat loss control. For instance, the graph (below) shows the heat loss control of the spray-in-place urethane foam insulation. Any insulation will have a similar graph but with thicker amounts of insulation. This graph points out that more insulation is not necessarily cost effective. There is a point where more insulation is pointless from a total heat loss perspective.

The graph shows that 70% of heat loss from conductance is stopped by a one inch thickness of spray-in-place urethane foam. Remember we are going to stop nearly 100% of the heat loss from air infiltration with the first one-fourth of an inch of urethane foam. The second inch of spray-in-place urethane stops about 90% of the heat loss and the third inch 95% and so forth.

Thermal Diffusivity and Heat Sinks

It should be noted that when the urethane is used on the exterior of a heat sink, such as concrete, the actual effective R-value is approximately doubled. This is why with the Monolithic Dome, we are able to calculate effective R-values in excess of 60. A heat sink is any substance capable of storing large amounts of heat. Most commonly we think of concrete, brick, water, adobe and earth as heat sink materials used in building. The property of a heat sink to act as an insulation is called thermal diffusivity.

The simple explanation for the way it works is: As the temperature of the atmosphere cycles from cold to hot to cold to hot the heat sink absorbs or gives up heat. But because the heat sink can absorb so much heat it never catches up with the full range of the cycle. Therefore, the temperature of the heat sink tends to average. Large heat sinks will average over many days, weeks or even months.

An example is the adobe hacienda with its 2 to 6 foot thick walls. By the time the adobe walls begin to absorb the daytime heat it is night time and the same heat then escapes into the cooler night. Therefore the temperature would average. Because the mass of the adobe is so large the temperature averages over periods of months. Adobe acts as an insulation even though adobe has a minimal “R” value.

You can see from the graph that urethane thicknesses beyond four or five inches is practically immaterial. We use three inches for most of our construction. Two inches will do a very superior job. We have insulated many metal buildings with one inch of urethane and the drop in heat loss is absolutely dramatic. Obviously the first quarter inch takes care of the wind blowing through the cracks. (It usually takes an inch to be sure the cracks are all filled.) The balance of the inch adds the thermal protection.

II. Surface temperature control

Surface temperature control is the second reason for insulation. In many cases it is the most important reason for the insulation. I noticed this phenomena first while insulating potato storages.

We had various customers ask us to insulate the buildings anywhere from two to five inches of urethane. The buildings insulated with two inches would hold the temperatures of the potatoes properly, just as well as the buildings insulated with five inches. The difference came in the condensation. Potato storages are kept up at very high humidity levels. The buildings with the two inches of urethane would have far more condensation than those with An engineer from the Upjohn company explained this to me. He stated that thicker insulation is absolutely necessary to maintain higher interior surface temperatures. One and a half inches of urethane on the walls and ceiling of a potato storage would control the heat loss from the building, but it took a minimum of three inches of urethane to control the interior surface temperature. Four inches was even better. With five inches the difference is practically negligible. The only place where we have felt the need for five inches of urethane was insulating the roof or ceiling of a sub-zero freezer.

Underground housing – surface temperature control vs. heat loss control.

Most underground housing is in trouble from mold and mildew growth. The cause is not enough insulation to control interior surface temperatures. Rarely is there a problem with total heat loss. Water vapor condenses on the surface allowing mold to grow. Mold makes people sick. The only solution is lots of insulation for temperature control and ignore total heat loss.

My experience is that R-value tables can be used as indicators. They need modifications to make them equal to real world conditions. There needs to be allowances made. They must show equivalents. These equivalents will be more like one inch of spray-in-place urethane equal to four inches of fiberglass in a normal installation. Footnotes to the table will need to define degradation of insulations in real world conditions. Only then will the “R-value” Fairy Tale become a real world success story.