DIY Insulation

In your standard row home, which architect Hap Haven says is more prevalent in Philadelphia than in any other American city, the area behind most walls is hollow. Chances are, a lot of your heat is being circulated through these areas and going to waste. Haven's got a do-it-yourself insulation technique on phillygreenhome.com that can salvage significant amounts of heat. (Haven estimates that with $50 in materials, you can save a minimum of $100 on your heating bill for the winter.) All you need is a drill with a half-inch masonry bit, four to six cans of foam, painter's tape and spackle:

Keep the holes about 4 to 6 inches below the ceiling. Start in a closet until you get the hang of how deep the wall cavity is. Rock the drill from left to right once you have drilled through into the wall cavity. This creates a horizontal slot into which you'll insert the can's nozzle.

Repeat the foaming down and to the right. Angling slightly up and down will give the foam more space to expand. The two areas of expanding foam will meet in the middle and push out the hole. Remember to shake the foam cans from time to time, and watch out for extra foam that might fall off the tip of the tube.

Create a "shelf" of extra wide painter's tape an inch or two below the hole. This should catch the excess foam as it expands out of the hole. Check on this foam from time to time until it has stopped expanding. Don't tape over the hole. You want the foam to expand out of the hole so it's easy to snap off when it's dry.

Let the foam cure for a minimum of two hours. At this time, you should be able to snap it off cleanly from the wall. Scrape off any excess with a spackle knife. Spackle and paint as necessary.