Old House, Old Walls, No Insulation?

One thing about old houses, especially really old houses: if they haven't been upgraded, the walls are probably insulation deficient.

What should you do? The answers are not cut and dried. They require a lot of homework on your part. Better yet, a complete energy assessment (or audit) of your house can tell you all the ways you can save energy. The U.S. government's energysavers.gov Web site explains how to get an energy audit, and it will guide you through a do-it-yourself version.

Check for Insulation

After turning off power to the electrical circuit, you can perform a quick check of your wall insulation by removing the corresponding electrical wall plate and probing and peering into the wall beside the electrical box. If you have insulation, you may even be able to retrieve a sample to see what type it is. Check walls in several parts of the house, remembering to turn off the power to each circuit involved before you start poking around.

When Insulation Is Needed

It would be nice if your insulation concerns were connected to a big project, maybe a remodel where you are removing drywall, or maybe replacing large areas of exterior siding. That would be a great time to install wall insulation. If you were actually opening up the walls to the studs, you might even consider furring the studs by two inches so you could insulate to today's standards.

Easy Insulation: Blow It in?

Most likely you will not want to take such drastic measures as opening the walls; you'll want to insulate enclosed walls with a minimum of disruption. This is usually done by blowing either foam or loose-fill material into the wall; however, foam insulation is not a job for an amateur; it sometimes will expand to a point of bowing the wall, and must be used with caution. You can try blowing in loose-fill insulation yourself, but a pro will do a much better, quicker and cleaner job.

If you insist on doing it yourself, insulation can be blown in either from the house's interior or exterior. A hole, 2 ½" to 3" in diameter is drilled at the top of the wall between each stud (16"), and the insulation is blown down between the studs to fill the wall. Loose-fill cellulose, made from recycled newspaper is one popular eco-friendly material.

In a house with horizontal exterior siding, the top row or two of siding can be removed before the holes are drilled, making it easy to hide the work. Conversely, if you have a brick exterior, you pretty much are forced to go inside for the insulation installation. The interior work should be accompanied by plans to repaint the interior walls, making it relatively easy to repair the holes in the wall.

Whichever way you add insulation, it is a lot of work and expense…which is another good reason to get that energy audit. You may find out your walls don't need insulation after all.