February 2, 2014 by Sarah
The insulation is in.
Actually it was in, and then it was out, and now it is in again.
Let me explain…
We had an energy audit done by Xcel Energy on our home shortly after moving in with the blower door test and infrared camera—the whole works. Obviously the tests showed that the whole house is leaking air—um duh. I have a bone to pick for Xcel Energy for a few reasons:
- After evaluating the house they said there was no insulation in any of the wall cavities. Trusting this, we ripped open the kitchen walls expecting to see no insulation. We were surprised to see blown-in cellulose in some of the cavities. Also having ripped into some of the walls as needed throughout the rest of the house, some areas have insulation—although spotty at best. It’s just annoying that they are supposed to be experts at this crap and they cannot even tell me which walls have insulation in them.
- They come into your home and tell you to spend 10s of thousands of dollars on insulating your home and upgrading your appliances, light bulbs, windows etc so your energy consumption will go down. The fact of the matter—it will take a long ass time to recoup the costs of thousands of dollars worth of these types of upgrades. You really have to weigh to pros and cons of spending that kind of money. Some upgrades will pay for themselves sooner than others and it really depends how long you think you will be living in your home. I am not going to dive into it any deeper than that, but make sure you do plenty of research before going ahead with any recommendations.
Back to the insulation–We decided to go with R-13 kraft-faced fiberglass batts from Menards for the kitchen exterior walls as well as spray foam around the windows.
Update: A reader brought up the importance of using the proper spray foam around windows and doors. The window/door formula doesn’t expand as much and is flexible to allow for expansion and contraction of the walls/windows. If you use the wrong type of foam it could expand so much that you won’t be able to open/close the windows/doors. Thanks Chris!
In our area of MN for a wood framed house the recommended R-value for exterior walls is R-20. The only way we would have been able to get R-20 was if we furred out the studs to essentially make them into 2x6s to accommodate a thicker batt, or we could have used closed-cell spray foam.
Our decision was based on a two things:
- Cost—Fiberglass batts are one of the least expensive options.
- Easy to work with—FG Batts are very DIY friendly and easy to work with and install without expensive equipment.
We did give some consideration to other types of insulation including closed-cell foam insulation and blown cellulose insulation. The expense and trouble of these products was not worth the extra insulating value in our case. (If I had all the money in the world I would have gone with the closed cell foam for sure)
I won’t go too far into this but there is A LOT of great information out there regarding the different kinds of insulation and the pros and cons of each. If you are interested check out the links here, here, here, and here.
You have to be very careful to install fiberglass insulation properly to get the most out of it. Some very basic things to keep in mind that I found helpful (photos all from Family Handyman since I forgot to take any photos):
- DO NOT compress the FG in the wall bays—the FG insulates better if it is at is light and fluffy full thickness.
Pancake batt = a lower R value.
- DO make sure the batts run completely all the way up to the top and bottom of the bays without any gaping at the top and bottom.
Gaps = air leaks.
- DO make sure to split the batts as needed to accommodate wires and other obstructions in the wall cavities. Wire generally run through the middle of the studs and wall cavities so it is always best to split the batt and then ‘sandwich” the wires between the 2 flaps you have created to make sure there are no air gaps in front or behind the wires.
Again, gaps = air leaks
There are two ways to do this properly:
- Cut the outline of the electrical box into the FG batt but DO NOT cut all the way through the batt—only cut halfway and remove the front portion of the batt. Position the half cutout area behind the electrical box to fill the gap and fill around the box.
- Use canned spray foam to insulate directly behind the electrical box where no fiberglass will be. Wait for the foam to dry then cut any excess that extends beyond the sides of the boxes. Cut all the way through the fiberglass so it will fit snugly around the electrical box/spray foam. This is the method we used.
Sure pushing the batts around the outlet boxes and other obstructions is faster and more convenient than taking the time to meticulously cut the batts to make a snug fit, but you will get the most out of the insulation if you do it the right way.
- DO make sure you use the proper kind of FG batt for your application.
Batts come in faced and unfaced and in different lengths and widths and are each used for different purposes. For the exterior wall here we are using kraft-faced batts which have a kind of tar paper type coating on one side. The kraft acts as a vapor barrier/retardant and that side should face the finished/heated side of a wall. You could also get unfaced batts and then apply your own vapor barrier with sheet poly and tape. We decided to use kraft-faced batts purely for the convenience and ease of install.
Around the windows (new and old) we used canned spray foam. We used the Great Stuff pro series spray foam with special applicator gun.
We have had the gun for about 4 years and it is a really nice tool to have if it will get use. If you are only doing a small project then there isn’t much sense in getting the gun—the regular can works okay although it is harder to control.
Insulation is a wonderful thing—however, all the insulation in the world will not help if the air leaks are not properly sealed prior to insulating. StructureTech (the company that did our home inspection) recently wrote an article about this very topic which you can find here. There is a lot of research out there regarding air sealing and its benefits. The good thing about air sealing is that it is inexpensive and easy for homeowners to do themselves with some elbow grease and it gives you a lot of bang for the buck.
Now we just need to insulate the other 80% of our house. What type of insulation do you use or plan to use in your house? Did you do it yourself or hire it out? I noticed a new neighbor across the street had cellulose blown into his attic a couple of months ago–I should ask him about it.
Anyone happen to notice a bit of drywall in the photos? I have never been more thrilled about walls in my life. More to come on that later in the week.