Last post we talked about how insufficient annular space and/or sealant depth can have a major impact on the performance of a firestop installation. We talked about a metal pipe in that scenario, but what if
We are not talking about a metal pipe, but rather an insulated pipe or duct? Then, the scenario gets worse faster. The firestop material required to be used will be an intumescent material.
The tested and listed assembly is going to call out a prescribed depth of sealant that will be required to close down the opening around combustible material or around gaps created in ducts. Read this post if you want more information on this.
If there is just a thin coat of sealant there will not be enough intumescence to close the gap, not to mention that the sealant needs to be installed between the penetrating item and the inside edge of the opening so that the expanding firestop can be directed to close down the gap. Firestop follows the rules of nature in that it moves in the direction of least resistance. If it is sitting on the outside edge of a wall it will expand away from the wall. If it is wedged between the edge of the opening and the penetrating item it will have no choice but to expand towards the gap that is created and fill it before fire, smoke and toxic gases can get through.
Penetrating items can’t always be centered in an opening, so what is the proper way to firestop a penetrating item when it contacts the edge of the opening? Check in to our next blog post for that answer. Until then, keep learning and keep your firestop installers on their toes!