Condo Attics and Firewall

I did an inspection on a condo today and when in the attic, there was no firewall on the wall dividing the units. it would appear there is 5/8 drywall on the ceiling its self and sprinkler system in every room of the unit. does it need to have fire wall on the walls in the attic as well or no? this is in Colorado

In my area there should be a firewall installed between the units, also if the units all have attic access points someone can enter the unit from another unit through an unsecured attic hatch. I found this condition last week.

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Same around here. Although, some older construction multi unit dwellings were built without any.

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The units are separate so that is good. There is a sprinkler system in each room of the unit and even in the primary closet where the attic hatch is. the building is a 2020 and it was almost a perfect inspection so makes me think that it is ok? not sure…

I’ve never seen that in modern construction with or without sprinkler.

Codes aside, from a practical standpoint, there should be a fire separation. Even with drywall in the ceiling, fire will eventually find its way into the attic. Houses aren’t that tight. Once that happens, it’ll spread through the attic pretty quickly. Unless you have a very aggressive fire crew fighting the fire, the whole building might be lost. How many units shared that attic space?

I was always under the assumption that the fire separation was meant to slow down spreading long enough to hopefully get people out of the building. In other words, to save lives and not necessarily the building.


One is not exclusive from the other. We protect both and stopping the building from engulfing in flames will save lives.


9 units. It would be my understanding when it comes to a fire wall and a garage, as long as the ceiling and anywall that shares wall with the home has firewall, then the attic does not need to have a separation and can be open? does this differ in a condo?

With proper fuel, a house fire can double in size every minute.
Having an open/breached firewall is bad. It creates a strong back draft.
It would be better to have none.

You are correct. The priority is life, property, and environment, in that order. Like Brian pointed out, there is considerable overlap.


I disagree.

Kind of, at least in my understanding. Regardless of the garage, units need to be completely separated by a firewall.

twinhome firewall

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It is different with multi-family dwellings. The idea is, if you start a fire in your garage doing something careless (storing a gas can next to a non-FVIR water heater) you’ll only burn your own home down. If one of your neighbors does something careless in a multi-family dwelling, you and all your neighbors can lose their home. In addition to that, egress gets more complicated the larger a structure is. That’s one of the reasons why the bigger the structure, the more stringent the fire codes, with high-occupancy commercial one of the strictest of all.

Also, if a large building gets fully involved with fire, it can burn down adjacent properties and start a conflagration like the great fires we heard of in history class. Those don’t happen much anymore because of modern fire codes. A fully involved 2000 sq/ft house isn’t as much of a threat. That’s another reason the codes aren’t as strict for single-family homes.

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Been searching for answers on the ole Interweb… So far, it is looking like firewalls are required in the IBC with no exceptions for fire sprinklers. That agrees with the InterNACHI training materials.

Of course, that requirement could vary by the AHJ. But, that should not unduly influence a HI. Safety is your first concern and the occupants would be safer with firewalls. Period. A note that the sprinklers are not likely installed within the attic space, so fire inside the attic would readily spread to other units.

Side note: It looks like some types of commercial buildings can have x,xxx square feet area for certain use types between a firewall / building separations(?). It did not seem those rules applied to residential…

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I’ve always understood the firewall need to be type x gypsum board for proper firewall separation. Plywood is not a firewall correct?

Typically not…

This is all covered under Table R306.6

From the residence and attics Not less than 1/2-inch gypsum board or equivalent applied to the garage side. Vertical separation between the garage and the residence attic shall extend to the roof sheathing or rafter blocking.

In short, the garage needs to be separated from the house in case of fire, but this isn’t a fire-rated assembly, nor is it a firewall. The best term for this required separation is a fire-separation wall.

Welcome to our forum, Jenson…enjoy participating. :slightly_smiling_face:


Without a wall to separate the units it would be a bit unnerving to know that one condo owner could go into their attic and enter another unit through the attic scuttle.


Sounds like they may have used a fire-separation assembly (as opposed to a fire-wall) with a fire suppression system. This is building code compliance stuff and outside of a general home inspection.

type x gypsum or equivalent. What is the equivalent? Down a rabbit hole you shall go. One clue might be that plywood was used here, when conversely OSB was the common sheathing material at other parts of the home.

This said, I typically see a fire rating or stamp on plywood/osb which is treated and rated.

Is this a mult-family dwelling? More than 2 units?