Insulate to convert a garage or basement

Q: Dear Jim: I need more living space, so I am building a new, detached garage and going to convert the basement and old garage into rooms. What options do I have for insulating and finishing the walls? I would like to be able to do some of the work myself. - Michael J.

A: Dear Michael: Your idea of building a new garage and converting the old garage and basement to living space makes a lot of sense. It is less expensive overall to build a new brick, framed or block garage than to make a major room addition.

You have many options for converting the basement and old garage, but whatever method you choose, you will have to add some insulation to the walls and you may want to also insulate the floors. This is not only for your family's comfort and for lower utility bills, but the building codes in most areas will require a certain level (R-value) of wall insulation.

The method you use to finish the basement walls will probably be different than for the garage. There are some very nice basement wall-finishing systems available that include the insulation, attractive fabric-covered wall panels, and everything else for a finished room. The seams between the wall panels are covered with finishing strips so they are very attractive.

These types of wall finishing systems are designed to handle the higher moisture content from basement (underground) walls, but they may work for above ground applications too. The only problem may be the above ground insulation level required by code may be higher than for basements, so the system may not meet the code. Also the moisture barriers for basement applications may not be positioned properly for above ground use in your area. If you choose to do the wall insulation yourself and not use a preassembled system, you will probably have plenty of room in the basement for standard batt insulation. This is your lowest cost option. If space is limited, as in your old garage, and you need as much floor space as possible, use rigid foam insulation instead of batts.

Rigid foam insulation has about a 50 percent higher R-value per inch thickness, so the walls

18 ILLINOIS COUNTRY LIVING www.icl.coop

can be thinner and still meet code. Some rigid foam insulation sheets use a closed-cell material so they function well as the vapor barrier and will resist degradation by moisture or high humidity. Some types have special multi-layer moisture resistant coverings on each side so they can also be used in the basement. They are available from 1/2 to 4-inches in thickness.

Check your home center store for rigid foam panels with notched edges designed specifically for finishing masonry walls. These are ideal for your job because the notches allow the furring strips—thin wooden strips used for attaching paneling to other wall material—to be recessed into the panel for a smooth surface. This provides a good nailing base that is easy to finish and there will be no breaks in the insulation. Most foam insulation should be covered with drywall for fire safety reasons, but again, check your local codes.

If you want to do the work yourself and your garage has a window, which you want to open at times, you might consider just building movable wall insulation panels. These are very functional and efficient and can be made to look attractive.

The basic design uses four decorative insulation panels. The two outer panels are fixed to the garage wall and the center ones slide open if you want to open the window for ventilation or light. The panel frames are made of standard lumber and surround rigid foam insulation to compose the entire panel. Cover the panels with drywall for fire safety and then finish them with fabric, paint or wallpaper to match the room decor.

For most do-it-yourselfers, it is easier to hang the panels from the top (similar to sliding closet doors) rather than having them roll in tracks on the floor, which would require more careful fitting. The small gap at the bottom will not be a major energy loser; however, installing a sealed bottom track would be better. Space the outer two end panels out from the wall with tracks installed behind them for the inner panels to slide on. Caulk the fixed outer panels and weather strip the edges so they seal well against the movable panels when closed.

Write for (instantly download - www.dulley.com) Utility Bills Update No. 748. Please include $3 and a business-size SASE. James Dulley, Illinois Country Living, 6906 Royalgreen Dr., Cincinnati, OH 45244.

James Dulley is a mechanical engineer who writes on a wide variety of energy and utility topics. His column appears in a large number of daily newspapers.

JULY 2003 www.aiec.coop 19