This is Lesson 5 of our informal online course: Home Energy 101. All lessons by Philip Drader.
This lesson is all about your walls and, specifically, whether they have insulation in them or not.
Stop and think about it. Your walls cover the most area between where you live and the heat or cold outside. They can have a noticeable impact on how high your energy bills are and how comfortable rooms in your home feel. Insulating your walls is a good way to cut down on drafts as well. So it’s extremely important to consider walls when making your home energy efficiency game plan.
Should you insulate your home’s walls?
If your house was built prior to 1950 and hasn’t had a renovation done for energy efficiency, it’s quite possible that your walls have no insulation, and that filling them with insulation is a slam-dunk. If so skip to the next section to learn how
If you are not sure whether your walls are insulated, you can check by pulling off electrical cover plates and looking inside the wall cavity to see if any insulation is visible. You may also need to remove some drywall. Pay attention to the wiring to avoid cutting it. Here’s a post that goes into greater detail on how to determine if your walls have insulation.
In a home built between 1950 and 1990 with insulation in the walls, you should consider exterior insulation to help bring it up to current standards if you plan to redo your siding. Or you may choose to remove your drywall to reinsulate from the inside.
How to insulate your older home’s walls
One of the common ways to add insulation inside the walls of an older home is for a contractor to drill small holes between wall studs and to blow in insulation to fill the empty space. This procedure can be done from the inside or the outside.
Here’s what the holes can look like in brick or on the inside . You’ll want to do this before you plan to repaint a room!
Ideally your contractor will use an infrared camera to ensure that the insulation fills the cavity entirely and that horizontal wood in your framing as fire-blocking isn’t in the way.
Doing a full-gut job
The other common way to insulate a wall is to remove the plaster or drywall as part of a full gut-rehabilitation. You’re essentially rebuilding the wall from scratch. This method is used when a) you want to do a lot of extra work within the walls (like replace all the wiring and plumbing vents), b) the walls are showing severe cracking problems already, or c) you want to insulate to a higher level than the space currently has or allows.
Consider the flash-and batt technique
If you have done or are planning a gut-rehab, consider asking your contractor to add an inch or two of 2 lb spray foam in the cavity before you fill it with batts. That small bit of foam can really help to seal any holes in the wall that would let air through. Your rooms will be more comfortable as a result. The technique is called flash-and-batt and there are many articles online that will give additional details.
Walls are important for a comfortable home
Many people want to change their windows to make their homes more comfortable and energy efficient. While that can help, it is important to remember the walls they are in if you want to achieve that goal.
Properly insulated walls are important to getting the best results from your new windows, new furnace, newly insulated basement or attic. They work together to help you live in your home more comfortably and affordably if your walls are also doing their part. Ensure they do!