top of page

Insulation Trends & Insulation Myths

Updated: 7 days ago

According to the latest industry trends, fiberglass looks to have been toppled from its throne as the king of cost-effective insulation.

Savvy buyers are choosing a variety of different insulation systems over fiberglass for many reasons. Vapor barriers, mold problems and the elimination of ventilation are three main components in the decision to switch. Others are swayed by heating and cooling cost savings. And of course, certain of people are intrigued about these new systems just because they’re something new.

Here are the competing newcomers, in descending order:

Cold Climate System: This insulation system has existed in cold climates such as Canada and Scandinavia for years. The most important consideration with a cold climate insulation system is that there needs to be a thermal break (such as insulation board) on the exterior of the building, followed by an airspace between the thermal break and the exterior siding or roofing.

The cold climate insulation system can be augmented further by using advanced framing. The key concept with advanced framing is to use fewer framing members to construct the exterior walls and avoid double framing members as much as possible. Framing members are the weak link in virtually all insulation systems. They provide a thermal transfer, and an easy way for heat to escape.

Spray foam and advanced framing with insulation board installed beneath the siding will give you an extremely high R-value/Insulation value. This system could bring you the most value for your dollar, especially as many custom homes are more complicated to build than traditional designs. A more complicated design is more expensive to insulate with an SIP system.

No lead time is required, changes and remodeling are done using conventional methods, and there are no special accommodations needed for the plumbing and electrical work. Another advantage with this system is that any remodels, repairs or rot issues that may come up can be dealt with in a simple, straightforward fashion.

SIPs (Structural Insulated Panels): These are factory produced panels using foam and OSB plywood. Think of a giant Oreo cookie. These two-sided foam panels with OSB plywood get their strength from the bond between the foam and the two plywood layers. They function just like a very broad I-beam!

The easiest place to use these panels is installment over a timber frame roof system; provided the roof is not too complex. Unlike walls, which have many window and door cutouts, the roof will typically have only a few openings. Windows and doors ore often subject to last-minute revisions or job site changes. It is also very convenient to simply install SIPs over the timber frame instead of installing roof framing members.

SIPs also enjoy the benefit of reduced construction time and an extreme reduction in framing members. Just remember to place your order well in advance, because lead time can be somewhat substantial.

Open and Closed Cell Spray Foam: The sealing properties of foam are promoted as having the ability to eliminate mold and be superior in a whole-house insulation.

Open and Closed-cell spray foam vary in cost and effectiveness: Closed-cell spray foam performs better in sealing cracks or making a space airtight. Some people have chosen to use a combination of cellulite or cotton with a thin layer of the closed cell foam. This combination gives you the airtight benefit of closed cell foam without the cost of filling the whole wall or roof cavity. Another benefit is the added strength gained when filling the stud spaces with foam. Closed-cell spray foam has been put through stress tests to ensure quality.

Open-cell foam is less expensive and does a great job of insulating when the whole wall or roof cavity is filled. And because foam allows no air movement, it eliminates the need for ventilation.

Cellulite and Cotton: Cellulite or cotton is applied with a spray apparatus similar to spray foam. The shredded cotton or cellulite is mixed with glues to adhere to the walls and avoid settling. Cellulite and cotton are a better choice than fiberglass because they dry easily if they get wet and will naturally breakdown if thrown away in a landfill. Another advantage these have over foam is the lack of petroleum ingredients, while still containing glues and fire retardants.

Straw Bale System: I think of the straw bale house as a neat, whimsical solution, provided it is built in the right environment or climate. The stucco and deep window wells go well with an exposed timber frame.

Historical artistic "half-timber" building.

Flash and Batt System: In my opinion, the Flash and Batt system is the best situation to use fiberglass insulation. This system uses a thin layer of closed-cell foam to keep the exterior envelope airtight and then the fiberglass insulation provides the R-value. This addresses the Achilles’ heel of fiberglass insulation, which is its’ inability to move air. If your exterior walls are not sealed properly (allowing air movement) – then you will not get good R-value from your fiberglass insulation.

I want you to be aware of the many other insulation options available to you that may not be mainstream. Are you the type of person who does a bit of research before buying? There are many other non-mainstream insulation options available to you and some of these alternate systems could potentially fit your situation to a tee.

In light of growing awareness of energy conservation and problems associated with poor insulation systems, we strongly encourage you to research your options before choosing any type of insulation. As you are moving forward with the mindset of a timber enthusiast, you are certainly someone who will want to make an informed choice.

To your momentum and success - Bert Sarkkinen

P.S. Below are excerpts from David South’s article giving an explanation of insulation values and trends. David B. South is President and founder of Monolithic, Inc., headquartered in Italy, Texas. His article explains the major flaw in the R-value ratings system. It is a bit technical, but you will get a sound understanding of all the factors which will influence how well your insulation system performs.

Excerpts: The Myth of Insulation Values by David B. South

The R-value of an Insulation Product, is commonly misunderstood and ignored.


An insulating material’s resistance to conductive heat flow is measured in terms of its thermal resistance or R-value. The higher the R-value, the greater the insulating effectiveness.

The R-value depends on the type of insulation, its thickness, and its density.

Consider the R-value of an insulation after it has been submerged in water or with a 20 mile per hour wind blowing through it. The R-value of fiber insulations would go to zero.

Under the same conditions, the solid insulations would be largely unaffected. R-value numbers are “funny” numbers meaning 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, etc. In other words, one number cannot accurately describe anything.

The use of an R-value alone is irrelevant yet we have code bodies mandating R-values of 20’s or 30’s or 40’s. A 25 R-value fiber insulation placed in a house not properly sealed will allow the wind to blow through it as if there were no insulation at all. The R-value may be accurate 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, free water, and 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 by 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 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 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 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 degrees below zero outside, the inside of an occupied house is certainly the warm side. During the summer months, when the sun is shining, 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 storages 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.

At very cold temperatures, when the temperature difference across the attic insulation reaches a certain critical point, convection within the insulation can reduce R-value.

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 which becomes a source of water for rotting of the structure. The water, as a vapor or condensation, will seriously decrease 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 Rvalue.

Air Penetration

The filter type 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.

Surface temperature control

Surface temperature control is the a reason for insulation. In many cases it is the most important reason for the insulation. I first noticed this phenomena while insulating potato storage buildings . We had various customers ask us to insulate the buildings with 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 storage buildings are kept up at very high humidity levels. The buildings with the two inches of urethane would have far more condensation than those with the five inches. 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 building would control the heat loss from the building, but it would take a minimum of three inches of urethane to control the interior surface temperature. Four inches would be 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.

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 become a real world success story.


bottom of page