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Monday, December 7, 2009

Crawlspace Insulation

I was home again for Thanksgiving weekend.
No, I did not work on Thanksgiving...

Friday through Sunday was spent insulating the crawlspace underneath the first section of my house. I am unfortunate enough to not have a full basement like some of the other houses in the area, so I was inching around on my stomach using my feet to move me along! Though it is proven that the majority of your money spent on heating (something like 42%) is lost through an uninsulated attic, an uninsulated basement and crawlspace can also contribute to heat loss...especially if it is not sealed off from outside winds. So I decided to get that out of the way before the weather turned.

To insulate your basement/crawlspace you first need to measure the area. Figure out exactly how much space exists between joists (usually 16 on center...so you'll need insulation about 14 inches wide) and multiply that by the width of your house. This gives you the area of one open space...now you need to figure out how many joists span your house and multiply the area for one open section by the number of open spaces that exist in between your joists. This calculation is a bit confusing, but once you start doing it you should be able to figure it out...


I decided on ordering rigid foam from Thermal Foams, a local distributor on Kenmore Ave. They were very helpful and for a small fee they delivered directly to the doorstep. Once you have your insulation ordered and set to be installed, follow the step-by-step below:

1. If you ordered pre-cut 8ft strips (ex. 14" x 8ft), then skip to step 3. If you ordered large sheets and want to cut them yourself for greater precision (the differences in my widths varied from 13" to 15+"), measure the spaces between the joists and cut the strips to fit. I used a table saw to cut the strips, much faster than any other method, but it is doable with a handsaw. MAKE SURE YOU HAVE A NUMBERING SYSTEM so you know where the strips will go.

2. Rip long 1" strips from 2x4s or from any scrap wood lying around. You will be using this to hold up your insulation against the floorboards, so you need to make enough to keep the insulation up. An alternative to this would be to tack nails into the sides of the joists...although this may be a faster method, it also seems like a more flimsy method.

3. Go into the crawlspace (bring a headlamp and goggles or you'll inevitably get dust in your eyes) and start securing the insulation in place. If you have a nail gun, GREAT! If not, insulating will not be quick and easy. Shove one strip of insulation up into a space between the joists and secure it by nailing the 1"x2" strips just under the insulation. Do this for every exposed space.

4. You're almost done...now to the foaming. Because rigid foam does not conform to the shape of the space, it can leave unsealed air gaps. In order to decrease air infiltration, you need to foam the spaces where the wood and rigid foam meet. The easiest way is to buy spray foam in cans from any major hardware store (Dibbles, Home Depot, etc). You will need a lot of foam, but it'll be worth it in the end!

I have yet to completely seal the space by adding the spray foam, so if you're interested in seeing it in action, contact me! Unfortunately the foam is only useable in 40 degrees or higher...so I may have to wait until a warm winter day, or even springtime to finish this project. Meanwhile, I'm losing heat! Ah! I will be home this weekend and working on various projects around the house (namely insulation...finishing the insulation in the basement and in the attic). Definitely call me if you would like a demonstration...of insulation, of drywalling, anything!

Hope you're all staying warm this season.

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