van de Ven Construction LLC
Custom Builders and Insulation Specialists
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Common Misconceptions about Insulation
“More is better”
This may be true, but only under certain conditions. Key to insulation is that the air and moisture is managed properly. If air can flow through the insulation (a common flaw of fiberglass projects) or gaps between framing, the performance of the insulation is compromised and moisture that is part of the airflow may condensate on the colder surfaces near the outside “skin” of the house. In turn, this will result in mold and rot.
“More is better II”
The law of diminishing returns applies to every step. However, if you apply this rule in a mathematical way to the payback of insulation, you should live in a tent. I happen to be very happy to be living in an over-the-top well insulated normal size house and cut only 1.5 cords of wood for my woodstove. And, maybe, when I get around to it, I will install a boiler.
“More is better III”
Some building materials cannot handle the cold... A nice old brick home may not benefit from a perfect insulation package inside of the exterior walls. Depending on the brick that was used, the moisture in the brick may cause the surface of the brick to crack (commonly called spalling) and degrade over time. It is risky to insulate a historic brick wall without doing the proper research first.
“Energy Audits are Free”
Once upon a time, Efficiency Vermont would perform some energy audits at no charge. However, that was a long time ago. Currently Efficiency Vermont oversees independent BPI licensed auditors and the auditors charge typically a standard fee for their services.
“All Audits are the Same”
While some key elements are required to be part of every audit performed by BPI licensed auditor, the audits and reports differ greatly. Some audits focus on generating a flashy report that is very educational on general energy and heat loss issues while others are sparse and confined to a few pages. Some audits push towards preferred projects and limit the improvements to the type of work performed by the auditor. Also, some auditors specialize in performing audits and minimize their involvement in actual projects. It is up to the home owner to choose what style suits them best. An example report of one of our audits on an actual house is shown on the “sample audit” page
“Tight Houses Cause Sick Building Syndrome”
While it is true that someone living in a very tight house may experience Sick Building Syndrome, I don’t blame the airtightness of the house. However, if there is no proper ventilation, Sick Building Syndrome is a likely result. So, it is easy to prevent. And rather than providing some ventilation with a chainsaw to some walls or by “sloppy un-airtight construction”, I prefer a more sophistical approach. The best system is to install a Heat Recovery Ventilator commonly referred to as an HRV. But a smart use of bathroom and range hood fans may also do the trick. In any case, this is one of those issues that should not get ignored.
“Houses need to breathe”
A common comment I hear when speaking with fellow construction professionals is just that. “Houses need to breathe” because in the old day, before the days of insulation and plywood, rot was nowhere near as big of a problem as it is currently. Nobody can deny this fact. The improved technologies of insulation and tight construction have raised the risk that if moisture isn’t managed properly, it will do damage. However, I don’t think that removing the insulation from the stud cavities and replacing the plywood with barn boards such that any moisture will fly outside with the heated air you just paid for is the proper solution. And I am glad the people responsible for establishing the Vermont energy code agree with me.
“All insulation is equal”
I can’t deny that the fiberglass batt is labeled with the same R value of a comparable piece of rigid insulation. But I have yet to see it work the same, and I am not referring to some fiberglass that has served as the rodents’ jungle gym. Key to making insulation work is to minimize air movement. With fiberglass this is super challenging since fiberglass has no natural air stopping ability. This is probably why it is the preferred material for furnace filters and window screens. Dense pack cellulose is quite air tight (ever tried to vacuum a pile of it without clogging the shop vac filter?) or foam is super air tight since the plastic seals everything.
“If one vapor barrier is good, two is better”
There is only a theoretical case where two would be better than one. Truth is that some vapor will make it through or around the vapor barrier. Luckily almost all building materials can handle a modest amount of vapor. However, if there are two vapor barriers, it is likely that moisture will get in between, but then what? It can’t get out and whatever material is stuck between, it is going to live in liquid water... Maybe it is only plastic, then it will be ok for a long time, but wood?
“Foam is flammable”
Yes, under the proper conditions, foam will burn or char, just like most building materials. The flame spread is somewhat comparable to wood, but it produces significantly more smoke, just like plastic. You have to be responsible and observe proper distances from hot areas with foam. Hot areas we insulate with a combination of rockwool for insulation and high temperature caulk and aluminum sheet for airsealing. Also it needs to be shielded from living areas with sheetrock or intumescent coating in order to observe national fire code.
“Oh, if my house catches on fire, I will have bigger problems than some burning foam in the basement” In the old days, we could let customers like this go, but the new fire code makes this illegal. All foam needs to either be shielded or pass a certain test depending on where the foam is at. In laymen’s terms, the code calls for a foam with basic fire resistance in areas that are normally not accessed by the home owner, such as scary crawl spaces and impossible attics. However, if the attic has nice pull-down stairs and light and some type of floor, so it is likely that the homeowner will visit this space, this foam needs to be shielded by sheetrock or intumescent coating or similar. Note that T&G wood does not meet this fire retardance test.
“That fire protection stuff, my foam already has it in it”
This may be true. To my knowledge there is one type of insulation foam that has sufficient fire retarding properties such that it does not need a coating of intumescent coating to meet fire code. However, this foam is not very value conscious and if you need enough foam such that you meet the insulation code in Vermont, it is less expensive to install ordinary foam and cover it with sheetrock or intumescent coating. However, there are installers that claim this performance of their foam and they are actually partially correct. They just conveniently extend the code compliance from performance in small crawl spaces to accessible basements and the like, which is a different level of fire retardance.
“New windows will reduce your heating bill by 30%”
Everybody has heard that statement. I am still surprised the window manufacturers have not been taken to court for this, because it is simply not true. I have done numerous Home Energy Audits and worked on hundreds of houses, but I have yet to replace my first window simply for efficiency’s sake. Unless the window has broken panes or is so degraded it won’t shut, you get much more bang for your buck by insulating an attic, a basement or section of wall. Windows are just too labor intensive and too small to make a huge impact on your whole house heating bill. Also, you can only get so much R value out of a piece of glass. (Don’t take this the wrong way, my house has triple pane windows, so I do believe good windows are a good thing).
“Uncle Sam will pick up the tab”
There is some merit to this claim. On your tax return (line 52 of form 1040) you can claim a tax credit (not a reduction in taxable income, so this is much more valuable) for a portion of the insulation project. For most projects over $4,000 you can claim the maximum of $500 credit.
“The incentive programs are just too complicated”
The incentive programs are not so bad. It is however very challenging to project how much incentive your house or your project qualifies for in advance. However, as part of a normal Home Energy Audit, we use the online program that is made available by Efficiency Vermont and it projects exactly how much incentive there is available in addition to making a projection on how much energy you will save and how much your carbon footprint will go down.
“A void space in the wall is bad”
As a blanket statement, voids in the wall are a waste of space. They don’t necessarily have to be bad, but are definitely bad if the voids are between layers of the insulation package. The voids will allow air to travel between the insulation and heat (and possibly moisture) may travel around the insulation, reducing its effectiveness.
“Paint never stays on this house”
It is common to find major flaws in the insulation and moisture management of an insulated wall that has issues retaining its paint. One example was a project in Hanover, where two walls of the house needed to get repainted every year. The homeowner had even installed round vent caps at the top of every wall cavity, but that made no difference. It turned out that the fiberglass insulated wall had a gap in the sheetrock just behind the baseboard heater and the interior air made it into the wall cavity. Then, the air would travel up the cavity, while the moisture would condensate on the back of the sheeting, and would exit the house at the top of the cavity through the wall vents the homeowner had installed. We simply repaired the sheetrock after temporarily removing the base board heat. Now the homeowners could again resort to their hobbies, building violins.
“I will throw some fiberglass over it, that should seal it”
It will look good, and you got rid of the fiberglass without having to pay for disposal fees. Other than that, it has extremely little effect. As you can tell some time later, the fiberglass will have turned very dirty, from the dust and other filth that it filters out of the air passing through it. You can now be confident that the heated air that escapes your house has been properly filtered.
“I will do it myself”
There are several projects where we have worked with the homeowner to reduce the expense of the project without compromising quality. In principle I welcome the involvement of the homeowner, but I lay simple ground rules. When it comes to airsealing, fire code or insulation code, you will have to follow my advice, or I can’t & won’t sign off on the project for it to qualify for Efficiency Vermont incentives. However, there is - depending on the project - plenty you can do to help or reduce the cost.
“The Infrared Camera from my buddy says:”
And some claim to reflective insulation follows. Truth is that Infrared Cameras are very helpful in analyzing a building and its insulation issues. However, the image needs to be interpreted with care, in particular when it comes to reflective surfaces. I have for instance a few images of windows that at first glance look that they failed since part of the image is red. However, the image is actually a reflection of my own hand or face.
“Cheap insulation is better than no insulation”
This sounds like it makes sense. I believe in the saying “work that deserves to be done, deserves to be done right”. But there is another reason. If there is no insulation in your way, it is quicker and cheaper to install something good than to remove the cheap junk and then install something good. It is Extremely rare that we just install more insulation over the existing insulation.
“Insulation smells bad”
I don’t think any building material smells particularly good, but insulation is typically pretty neutral. However, we have removed enormous amounts of truly unpleasant smelling insulation, but it usually smells bad because of the rodent infestation.
“Foam off gasses over time”
In the past, foam insulation developed a bad reputation, frankly because it deserved it. In the sixties, there was a style of foam insulation that was briefly used for wall and ceiling insulation. It contained formaldehyde and would off-gass over time. Usually by now this foam has shrunk so much, it has become an ineffective insulation package due to the bypasses and air leaks it allows. This formaldehyde foam has been taken out of production for a reason.
The modern polyurethane foams don’t off-gass under normal conditions and are a preferred insulation system for schools and public buildings in addition to homes.
“Basements need to be ventilated to dry up”
I have lost more jobs over this statement than I care to remember. It sounds good, your basement is damp, so you turn on a fan in the window in the hope the fresh air will carry some of the moisture away. In reality, this rarely works. I have even seen new construction projects where the basement walls were completed and the house wasn’t even built yet, and there was already condensation in the bottom corners of the foundation. Usually this was blamed on the “poor site” or “cheap excavation company” or “lack of perimeter drain”. But, miraculously, after the house is done, the problem disappeared. The moisture suddenly stopped seeping out of the earth. Yeah, right!
But the real reason is this. In summer, the outside air is warm, say 80F. And it is humid, say 80% RH. At the same time, the ground temperature, at a depth of 8 feet or so, is 50F. So, the average basement, with average insulation is much cooler than the outside air. Now, if you fan that warm & humid air through your cool basement, it turns out that the moisture problem gets worse!! I often offer the following solution: 1. close the windows, 2. install a vapor barrier over any dirt floor, 3. install a layer of spray foam over any porous wall surfaces, such as field stone and concrete foundations. Then, temporarily, just to get ahead of the problem, run a de-humidifier to dry the basement. I don’t encourage running the de-humidifier ongoing, simply because it takes a fair bit of electricity and may jack up your monthly bill by some $50.00.
Note that these solutions assume that the grade outside the house is such that liquid water from rain and snow melt is directed away from the building.
"Because foam is waterproof, the insulation will stop the rain from flooding my basement"
There is some truth in this statement, but only a little. The foam itself is mostly waterproof. However, at transitions from floor to foam and other places where the foam bond is challenged, it is not 100% waterproof. So by merely spraying foam over everything, that doesn't solve the problem. Good thing, because imagine that the foam actually created a perfect seal, and the water that used to be able to run into the basement is stopped and collects behind the foundation wall. The hyrdaulic force exerted by the water (1/2*Rho*H^2*L) for an 8 foot tall, 36 foot long foundation wall calulates out to be 31 metric tons. A typical foundation wall will cave in long before that load is achieved. Suddenly that moist basement isn't so bad...
