I am interested in purchasing a duplex that does not have a firewall in the attic. What would I need to have done to get it installed? Would I need an architect/engineer evaluate the property before installation? Is the process in putting up a firewall more involved than putting up regular drywall? The property is in Florida and is single story. Any advice would be appreciated. Thanks!
I had to do the same thing for a 4unit that I purchased in Ohio. While the specific answer will probably depend on local building codes, what my city building inspector had me do was to first apply a 3/4" plywood substructure and then a 5/8" FireX drywall to each side of the truss. (by units are separated by a common area.) It did not require engineering or architect sign off.
Before anything, I would check with your insurance agent and local code. A duplex may not need a firewall. If it does, it may be as simple as running fire rated gypsum board up to the roof or it may be more involved again depending on your municipality. Of course, it is always better to have one, safety wise. Your insurance rates will most likely be lower. Marketability on the sale side will be greater also.
Many times an inspector will note that there is no firewall in a duplex, but just to mention it. Thats all. When you go over 2 units, there will be an almost 100% need to have a firewall.
I am a homebuilder in MD and we have to install "core wall" or fire rated drywall in the attic separating the units. We use metal "C" tracks and "H" tracks to frame up the support to hold the fire rated drywall. You have to use metal screws and also a break away L bracket to screw the metal tracks to the lumber in the roof. The idea is that if a fire breaks out in one unit, the clips burn and break away from the drywall so that the house on fire can burn and fall away without affecting the other unit. See my chicken scratch below. Let me know if you have any other questions...im not the best explaining it on this.
Thank you all for the advice! According to a few insurance agents I spoke to, it was necessary to have the firewall. I also just feel it's the right thing to do. I did have an engineer check it out and work up specs on building the firewall because this is my first duplex so I do not want to run into problems later with code enforcement. The engineer was someone my GC recommended and gave me a fair price for his services.
@Miles Rivas Thank you for the description. It makes the concept a lot clearer.
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