Last Wednesday on November 15th this home in Rapid City, South Dakota sustained minimal fire damage. The damage could have been much worse and completely destroyed the entire home were it not for the firewall which saved it. Most people don’t understand what is a firewall in a house. A firewall is a fire-resistant barrier used to prevent the spread of fire for a prescribed period of time. In this case, the firewall between the storage area and living space was able to contain the fire and prevent it from consuming the whole house.
Houses usually have a firewall between the garage and the interior living space. This firewall consists of fire rated sheetrock which can contain a burn up to one hour before it penetrates the interior of the home. The intent of it is to slow the spread of fire from the garage to the living space.
In order to accomplish this, several components of a house must be made of fire resistive materials, and all must be working together for the system to work. Drywall used on the garage side of walls shared with living space must have a one hour fire resistive surface.
If the garage ceiling is not covered with drywall, then the common walls between the garage and living space must be covered all the way up to the underside of the roof sheathing. You may see open rafters in the garage which is OK as long as there is no living space above the garage. In this example, if a fire starts in the garage, it cannot easily spread to the living space or the attic above the living space. It will be contained in the garage.
If there are breaches in the firewall they must be addressed to restore the integrity of the firewall. A breach in firewall could be a hole or crack in the sheetrock or even voids where sheetrock is missing altogether. Smaller breaches could include a missing switch plate cover to an electric outlet.
When a buyer gets a home inspection, the inspector will examine the firewall(s) in the home ensuring they are intact. Any voids will be noted as hazardous and should be addressed between buyer and seller prior to closing.
Sheetrock isn’t something we think about every day. And most of us don’t go around wondering if our sheetrock can contain a fire. But I’m sure the owners of this Rapid City home are grateful their sheetrock was intact and worked properly.