How to Build a Fire Stop in Basement Walls

Basement perimeter walls are installed over the home's concrete foundation.

Fire stops prevent the spread of fire through the home. They consist of a wood or drywall barrier that cuts off the path of a fire throughout the interior of the home. A fire stop is designed to block the oxygen and progress of a fire so that it cannot spread laterally, or to the floor above. Basement perimeter walls are often made of concrete with a drywall or paneling finish. Basement partition walls are constructed with the same wooden framework and drywall coating as in the rest of the home. Both can be fitted with fire stops.

Things You'll Need

• ¾-inch plywood
• ¾-inch drywall
• Circular saw
• Razor knife
• Hammer
• Nails
• Screw gun
• Drywall screws
• 2-by-4-inch lumber
• Power drill
• Wood bit
• Masonry bit
• 40-pound masonry nails
• Masonry screws
• Fire extinguishers
• Mineral wool
• Fiberglass sheet insulation
• Work gloves
• Eye goggles

Instructions

1. Install a piece of ¾-inch plywood or drywall beneath the floor joist at the top of your basement wall. The fire stop should be cut to the same width as the joist, and should be installed between the horizontal studs along the entire top of the wall. Use your circular saw or razor knife to cut the material and use your hammer and nails, or your screw gun and drywall screws to fasten the fire stop in place. If your wall has furring strips or is being installed over an existing concrete wall, move to step 2. If not, move to step 3.

2. Install vertical 2-by-4-inch studs from floor to ceiling every 10 feet throughout the entire wall. The studs should be installed with the narrow side facing inward, to provide for the proper amount of spacing between the finished wall surface and the concrete beneath. Use your power drill, wood and masonry bits to make pilot holes through the wood and into the wall. Use your screw gun and masonry screws or hammer and 40-pound masonry nails to fasten each stud in place.

3. Install a 2-by-4 along the entire length of the bottom of the wall against the concrete floor. Drill and fasten the wood in place with masonry nails, one every 24 inches or so. Install a second 2-by-4 over the first and nail it in place.

4. Install a 2-by-4 along the entire length of the top of the wall along the ceiling joist. Use your hammer and nails to fasten it in place. Install a second 2-by-4 about 12 inches below the top plate.

5. Fit the gap between the top plate and the second stud, and the gaps between the second stud and the bottom plate with 2-by-4s installed vertically. There should be one stud standing every 16 inches, and fastened to the horizontal lengths above and below it. As a result, of building this type of framework, the interior of your wall is sectioned off into boxes. Each box is designed to capture and hold a fire so that it cannot spread to the next box.

6. Install ¾-inch plywood or drywall sheets onto your wooden framework. There should be no spaces between the top of the sheet and the ceiling, or the bottom of the sheet and the concrete floor. Likewise, there should be no spaces between the sheet and the wooden framework beneath. Use your hammer and nails to fasten the sheets to the studs on all sides.

Tips & Warnings

• Keep a fire extinguisher on each floor of the house so that there is always one handy should an emergency occur.

• Keep portable heaters away from anything that may be flammable. A light breeze or a curious pet can bring together the elements necessary to start a serious fire.

• Check with local building codes and regulations to find out exactly what type of fire stop if any is required in your home.

• If any gaps remain between the plywood or drywall sheets, and the floor or ceiling, use mineral wool or fiberglass sheet insulation to close them up. The idea is to prevent any air from making its way through and feeding a potential fire.

• Use caution when working with dangerous tools like hammers, nails and saws. Serious injury can occur. Wear work gloves and safety goggles for protection.

References

• This Old House: Stop a Fire Before it Starts
• Ask the Builder: Fire Stop Construction