How to Apply Fire Stopping Mastic Around Uneven Fire Door Frame Gaps

Uneven frame-to-wall gaps are where a standard caulking approach breaks down. The joint may be narrow at one point, wider at another and deeper again around packers or local imperfections. That changes how the material can be applied, but it does not change the rule that the complete junction must match the supported fire-stopping arrangement. Measure the variation first Do not start by filling the biggest visible opening. Map the junction. Record where the gap is narrow, where it opens up and where the backing or packers change. Look at the head and jambs separately rather than assuming the same condition exists all around the frame. Understand what is behind the mastic BWF's current installation guidance highlights backing material, packer size, frame-to-wall gap and any required capping of intumescent mastic as part of selecting the correct linear gap-sealing system. That…