Q. We built a new two-car garage and we want to convert our old, attached one-car garage into a playroom. It has uninsulated masonry walls. Would we insulate and finish the walls just like a basement? — Paul M.
A. You will definitely need insulation on the walls or you will be uncomfortable and your utility bills will be sky-high.
Over the past several years, major wall insulation manufacturers have developed masonry wall insulation and finishing systems that make the job a snap. Because a one-car garage is not large, you will want to minimize the loss of floor space.
Choose a finishing system that uses some type of rigid foam insulation. This provides the highest insulation R-value per inch thickness and leaves more free floor space. A 2-inch wall finishing thickness can provide an insulation value as high as R-10 in addition to the masonry’s R-value.
You can find these systems at most major home centers. Look for ones with notched rigid foam insulation boards. With the edges notched the entire vertical length, it makes a perfect pocket for standard furring strips. Dow Styrofoam Wallmate and Truefoam Truewall are examples of this design.
The furring strips hold the rigid foam to the wall and provide a flush nailing base for the drywall. Most building codes will require foam insulation to be covered with a non-flammable material, such as gypsum.
Several companies (Homasote and Owens Corning) make insulation systems that have a completely finished fabric wall surface on one side. Once the insulated panels are up, the job is done. The Owens-Corning system is only installed by professional contractors.
An easy do-it-yourself project is movable wall panels, an ideal method if your garage already has a window. When the insulating panels are closed, the window is covered and insulated, too. When the weather is warm, they can slide open.
This wall insulation system consists of four simple panels made from 1-inch-thick rigid insulation boards. Cover them with 1/2-inch gypsum and finish them with any attractive material or fabric to match your room’s decor. The two stationary outside insulating panels are spaced out from the wall. The two center panels slide on tracks behind them. To close them and insulate the entire wall, slide them together from behind the outside panels.
Write for or download Update bulletin No. 805.
James Dulley is an engineering consultant. To get Dulley’s Update Bulletin No. 805, send $3 and a self-addressed business-size envelope to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244. To rush bulletin delivery or read all previous columns, visit
