Garage Fire Separation

So by now you have all read my Sub-contractor story. Wait, what!? You haven’t? Check it out here.  Since my “Interior Wall Specialist” did not finish the garage, I have had to take the time to finish the joints myself.  This requirement would interfere with getting an occupancy permit and must be done prior to move in.  That made me think a post on the fire separation requirements for single family homes would be informative, so here we go…

I would say that on over 40% of homes I inspect the fire separation from the garage to the living space is lacking in one manner or another.  There are many requirements to adhere to mostly dealing with what materials are used.

Walls and Ceilings

When it comes to the walls and ceilings, the wall covering is the largest indicator if the wall is in compliance.  Current building standards for the walls require a minimum of (1) layer of 5/8″ Gypsum board or (2) layers of 1/2″ Gypsum Board (generally referred to as Sheetrock in our area).   For the ceiling (1) layer of 5/8 inch gypsum board is sufficient for separation from a living space above or if the garage ceiling serves as the separation to a common attic space.  The joints between the sheets is not to exceed 1/20th of an inch, or must be taped and sealed.  These requirements are the current standard as taken from SPS 321.08(2) 

This leads me to the attic separation.  Many times when I arrive for my inspection and it is a 1950-1980 ranch style home, I assume the fire resistance is incorrect, many times they just don’t get updated.  Currently, if the attic of the garage and the house share the 1574103883205same space or there is an opening in between the two, a wall must be constructed in-between or the garage ceiling must be sheathed.  These materials must also be in compliance with the requirements above.  If you have a shared attic and the attic access panel is in the ceiling of the garage, this must also be secured to the ceiling.  If a fire were to start in the garage, thermal pressure can lift this panel allowing the fire to enter the attic, if that happens, it is all over my friends.

One other item that comes up seldom, but is worth mentioning, is when a radon reduction system is installed through the garage, the installer will run the vent piping through the box sill (joist cavity) into the garage then run it through the garage roof.  This is a perfectly acceptable installation, but the penetration through the garage wall must be protected with a penetration fire stop.

Doors and Windows

When it comes to doors and windows, (yes sometimes people have windows that face into the garage), There are also requirements for the safety of the occupants.  The door entering the home must carry a 20 minute fire rating to be in accordance with the most current building standard.  Hollow core wood doors and most doors that incorporate a window do not comply.  With older homes like the ones I generally inspect, for occupant safety I generally recommend a steel insulated door that is fully weather stripped.  In some jurisdictions a self closing device is required, but that has yet to make it to Wisconsin.

As far as windows are concerned, whether they be in the wall assembly or in the door as a lite, fire resistance is required.  Generally speaking any window you find in the common wall will not comply with the requirement and should be removed and replaced with materials that meet the standard mentioned earlier.  There are some doors on the market that include lites (windows) that adhere to these requirements, but I seldom find them installed.  For one the trim around the glass would be metal in lieu of plastic.

To summarize, fire resistance is a very important aspect to occupant safety.  While these fixes are generally inexpensive, they are very important and should not be ignored.  There have been many cases where the house was a total loss just because of these conditions.

Oh, you have a detached garage? Never mind what I just said, and carry on…

As always if you have home related questions, please send me an email at, I will help in any way that I can.




Aaron M. Zuehlke is the owner and inspector at Zuehlke Inspection Service, LLC, a full-service home inspection company serving Southern Wisconsin. Specializing in Home inspection, Radon Testing, Mold Testing/inspection and Residential Thermal Imaging. He can be reached by email at or by calling the office at 608-931-7485.



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