If the air barrier is damaged, it must be repaired. The materials used must provide at
least the same level of airtightness as the original construction. Gun-applied sealants are usually suitable for
sealing around service penetrations. Larger openings through walls and floors can often be filled with mortar.
Holes or tears in membranes can be sealed with appropriate adhesive tapes or heat welded patches. Not all
sealants will be appropriate, though: some, such as intumescent fire stop materials, may still allow air leakage
even though they fill voids.