A firestop is a passive fire-protection method designed to diminish the opportunity for fire to spread through unprotected openings in a rated firewall. Such openings are found around the perimeter of pipes and wiring that penetrate firewalls.
Places where firestops are required:
Firestops must seal all unprotected openings in firewalls. In homes, firewalls are found in the following locations:
- between the garage and the living space, including the overhead ceiling;
- between the attic and the living space. Inspectors should be on the lookout for fireplace and wood stove flues that lack adequate fire-rated sheetrock or metal flashing firestopping, as in the photograph at right;
- firewalls that separate condominium units are often penetrated by utilities that serve multiple units. These utilities are sometimes contained inside chases that should be sealed where they pass through the firewall between units. Firewalls between units must be continuous, all the way to the roof. Inspectors should check in attics of multi-family dwellings to make sure that the firewall has not been violated in the attic space.
Common Problems With Firestops
InterNACHI inspectors should call out any instances where firestops are missing, damaged, or otherwise inadequate. Brief explanations of firestop deficiencies commonly encountered by inspectors are listed below:
- missing firestop: Unsealed pipe penetrations will greatly reduce the ability for a firewall to contain a fire. This situation is more common in old buildings than in new buildings, due to changes in building code.
- cable or pipe replacement: Electricians and plumbers may partially remove a firestop in order to install new cables and plumbing. A firewall’s fire-resistance rating will be compromised if the opening created by this removal is not filled.
- improper installation: Firestops will be effective only if they are installed correctly. For instance, firestop mortars are sometimes smeared into place unevenly and lack the required thickness at certain points. Also, firestops that are installed only on one side of a penetration may not be sufficient to prevent the spread of fire through the opening.