Firestopping Before You Build

Basement fire stopping codes are new in some areas, but not for long. It is easiest to fire stop the basement before you do any framing or electrical. Since basement walls are not load-bearing, there is no continuous framing between the walls and the ceiling. Any fire (most likely electrical) would easily spread between and behind the walls and ceiling and up to the first floor.

Before building the walls, drywall the area on the ceiling between the ceiling joists to the rim plate about 1 inch behind where the wall will be framed. they are usually about 5 inches wide and cut them to 4 feet long.



Screw them to the ceiling framing, and use fire caulk to seal the crack between the drywall and the foundation. Tape and mud the drywall seams, and around exposed electrical conduit. When you build the walls, this forms a fire barrier between the ceilings and the walls, and also isolates the area behind the wall.

Soffits are a little trickier. These have to be isolated from the space behind the wall pocket, behind the wall and inside the soffit. Blocking (drywall) can be installed horizontally behind the soffit opening to the foundation, and then solid blocking (wood) can be installed between each stud. Any gaps can then be caulked with fire caulking or mudded and taped. Keep in mind that you want to have no air spaces between direction changes (walls to ceiling, walls to soffits, etc.) Soffits are considered part of the ceiling and only have to be isolated from the walls.





Beams, stairwells and columns also have to be isolated from direction changes, and this can be done with gluing tightly cut drywall into the space and then fire caulked. Smaller spaces can be filled with fire barrier, which is non-flammable and is easy to rip and jam into spaces too big for caulk and too small for drywall.




The bottom of stairwells needs to be drywalled and taped as well, even in unfinished storage spaces, to keep fire from spreading through the basement stairs to the first floor.

These steps are easier to do before the walls are up, and before the inspector comes to do the rough inspection, if you missed the fire code specifications on your permit.

A good basement finisher should know all these codes and should be able to do this step quickly. It may seem like over kill, but properly installed fire stops can starve a fire, and it could go out, or it may give the homeowner enough time to evacuate the house if the fire should be big enough to burn through to the next area. Forty-five extra minutes might not seem like a lot, but it is when it comes to the safety of your family.

Call for a free estimate if you live in Naperville, IL. or in the Chicago area. 708-479-4570 Visit nantom.com for more information!