Greenovation Blog — Spray Foam Insulation
If you have been following this series of blogs, you know that the home energy audit identified our attic insulation as the area of major concern. Below is the analysis that was provided in the energy audit report:
poorly installed overall. During construction, the insulation sub crew stapled the batts into the rafter bays from below. This technique pushes the batts higher than they should be installed and leaves numerous pockets and voids between the kraft paper and the drywall below. To be effective, insulation should be in close, continuous contactwith the surfaces that it’s insulating.
The following suggestions are listed in the general order of most cost (and/or comfort) effectiveness.
1. After foam sealing all accessible attic spaces (as described on page 5) including the top plates, electrical and
plumbing chases, and all recessed lights – then fix the insulation as follows:
a. Cut the kraft paper flanges to free the batts from the roof trusses.
b. Press the insulation down so that it is in even contact with the drywall below.
c. 2006 building code requires R-38 in ceilings and the Department of Energy (DOE) recommends R-49.
Blow in additional cellulose insulation to R-49. Blown cellulose will fill in the smaller nooks and spaces
between the batt insulation and provide a uniform R-49 thermal break in the attic.
I agree with the analysis of the situation, but through research we found that there were some alternative solutions that will provide better results. By using a soybean based, spray foam insulation to completely seal the attic walls and roof deck we are able to achieve the following benefits:
- Conventional insulation methods attempt to insulate the attic from the living spaces below. Meanwhile, the attic can exceed 150 degrees in the summer and can get well below freezing in the winter. By sealing the attic with spray foam insulation, the variations in temperature will only be about 10-15 degrees from that in the living space.
- Conventional insulation like blow-in cellulose and batt insulation do not prevent air leaks (around the batts) and air penetration (through the blown-in cellulose). These hot and cold air penetrations compromise the r-value of these insulation choices and defeat their purpose. R-30 insulation with air leakage can be reduced to an effective R-10 or less.
- Since we have a dual zone HVAC system, the upper-level air handler and ducts are all located in the attic. In the summer they are operating in an oven while trying to cool the upper level of our house. In the winter we have the opposite problem-they are freezing the ducts and chilling the warm air inside. By sealing the attic with spray foam insulation, the air handler will have a longer life by not running under such extreme conditions and will not have to use as much energy to heat and cool the home. Any leakage from the air handler or ducts will now work towards controlling the temperature in the attic.
- We kept our current batt insulation in the attic deck which easily handles any temperature fluctuations in the attic space.
- They claim to reduce HVAC energy use by as much as 30-50%. I’ll follow up with everyone in a year to tell you how it is performing.
- Unlike conventional insulation that will deteriorate over time, spray foam insulation will maintain its R-value.
- We don’t store a lot of items in the attic, but it is nice to know that the items we are storing up there are in a controlled temperature environment without all the humidity to make soggy and moldy.
- We no longer have to worry about all the nooks and crannies through which air was previously entering and escaping the attic from the living spaces below. Perfect examples are through the canned lights and attic hatch.
- Spray foam insulation is water blown and emits no harmful gasses once cured. You don’t have to worry about minute pieces of insulation and fiberglass being blown into your home for you and your family to breath in.
- Spray foam helps prevent moisture penetration, which greatly reduces the potential for mold growth.
- Foam insulation is not a food source for mold so mold can not grow on it.
The following diagram does a good job of comparing a traditional attic to one that uses spray foam insulation.
Resulting from the tighter envelope we have created, it is even more important that we follow up on another recommendation provided in the energy audit. We need to mechanically provide fresh air into the home for more air exchanges. We were already below the recommended number of air changes per day, so now we are even farther below that recommendation. Air changes are the number of times per day that you home cycles in and out fresh outdoor air. We will address this in a blog soon.
The cost to blow in foam insulation will obviously vary depending on the size of your attic. The footprint of our attic walls and roof deck is about 1500 square feet and the quotes we received were between $4000 and $6000. The company we decided to use is called Safe Green Attics/Green Clean Air – 703-927-7532.
According to our tax accountant we will be able to receive a federal tax credit for 30% of the cost to improve our insulation. More information about tax credits for improving energy efficiency can be found at the Energy Star website.
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We do a lot of closed roof deck jobs in Southwest Missouri where the climate varies, we have seen no problems with the spray foam insulation sprayed directly to the roof decks.
The only thing we have seen is people saying a lot of money with spray foam insulation
Hi,
I have read your blog with interest and it has provided me with some useful information. useful
I am a 4 level town house owner in Fairfax.I also plan to spray foam to the underside of the roof in the attic using a company called Nova Spray Foam.THe cost works out to around $3/sq ft.
Do you know spraying foam under the roof is permitted in the existing building codes
for Virginia.
Thanks,
VIshy.
Hi,
I have read your blog with interest and it has provided me with some useful information. useful
I am a 4 level town house owner in Fairfax.I also plan to spray foam to the underside of the roof in the attic using a company called Nova Spray Foam.THe cost works out to around $3/sq ft.
Do you know spraying foam under the roof is permitted in the existing building codes
for Virginia.
Thanks,
VIshy.
On what type of climate condition does spray foam insulation applicable? I am from Alberta, Canada where the climate condition is dry but yearly hailstorms happen. If it is possible in our place, maybe I would give it a try on my home and let the expert calgary roofing Contractors install it for me.
From your description I can't think of any reason why spray foam insulation would not be a good choice in Alberta. I recommend speaking with an insulation company rather than a roofing company to get this done for you. The Icynene site may be a good resource to find someone in your area and learn more about the benefits of spray foam insulation. http://www.icynene.com/
From your description I can't think of any reason why spray foam insulation would not be a good choice in Alberta. I recommend speaking with an insulation company rather than a roofing company to get this done for you. The Icynene site may be a good resource to find someone in your area and learn more about the benefits of spray foam insulation. http://www.icynene.com/
Has anyone proven the cost-effectiveness of spray foam installation yet? I’m really looking into it since I’ve had my drywall renovations Calgary in early October. If the spray foam really allows for HVAC energy saving, then that’s good news given our long, cold winters. I’ll get my drywall contractors in Calgary to look into this as well so we get things sorted before it starts freezing up.
There are some local guys who do a great job http://www.novasprayfoam.com/ You may want to see if they have any recommendations out your way. Good luck.