Fire rated drywall in attached garage

[70datsun]

Greetings, I'm building an attached garage that has a small addition (sitting room, pantry, and closets) between the garage and house. The plans call for 5/8 drywall on the garage wall attaching to the house, which makes sense. But it also calls for the drywall up to the bottom of the roof decking, rather than just on the ceiling. Since the nearest truss to the garage wall is offset from the top plate, it's going to be a real pain to drywall, tape and seal all of this. Has anyone encountered anything like this? I would much prefer to just drywall the ceiling!

 

[The Cobbler]

see if you can have the plans altered. alternatively just be methodical with measuring & cutting, you can do it !

 

[Stuart in MN]

I assume the plans were drawn up for you by an architect or engineer? Ask them - they may have assumed the truss lined up with the top plate and that would be the easiest method of blocking off the house from the garage. I've seen it done both ways but don't know if that's the case in your area.

 

[wasfuzz]

Yes it is common for fire block to call for 5/8 sheet rock to the roof deck with no opening allowed into common attic.

 

[readhead]

Make sure you use fire rated 5/8. It will be stamped on the board. You would hate to do all that work and fail inspection and have to do it all over.

 

[PCustoms]

Got A pic?

Planning out drywall now for my furnace room/garage below my house, so doing some research into the required drywall.

You could do probably do 5/8 on the ceiling, but probably easier to frame in a quick wall or gable truss on top of your top plate.

 

[70datsun]

Thanks to everyone for the replies!

I assume the plans were drawn up for you by an architect or engineer? Ask them - they may have assumed the truss lined up with the top plate and that would be the easiest method of blocking off the house from the garage. I've seen it done both ways but don't know if that's the case in your area.

Yes, they were drawn up by an architect. I thought about that, especially since it's not required that the garage be drywalled.

Got A pic?

Planning out drywall now for my furnace room/garage below my house, so doing some research into the required drywall.

You could do probably do 5/8 on the ceiling, but probably easier to frame in a quick wall or gable truss on top of your top plate.

Yes, I have been thinking about doing that. It's more material but would not be too hard to do. I'll see if I can post a pic later today.

Regardless of all this, I plan to rock the ceiling anyway, so it'd be nice to keep it simple. I'll contact the plan designer tomorrow and see what he has to say. Of course this comes up on a long weekend when I planned to get ahead on the project! Cheers!

 

[theoldwizard1]

Make sure you use fire rated 5/8. It will be stamped on the board. You would hate to do all that work and fail inspection and have to do it all over.

I have heard that 2 sheets of standard 1/2 drywall also meets the requirements of a fire wall. I do not believe that tape and mud are required on the first one IF the joints are staggered between the 2.

 

[Firebrick43]

This question is really a local question as it varies by location. Here you have to uses 5/8 on either the ceiling or the first truss, but not both.

However I would suggest you do both, as it may save your families and your life someday. I would put 5/8 fire drywall on both sides and fire blocking in that common wall as well.

A friend of mine in high school had their ford truck catch fire in his garage (ignition switch). The fire block in the truss saved the house even though it wasn't required.

To save effort they do make expanding fire foam. Use it to seal the perimeter of the truss drywall.

https://www.amazon.com/Fire-Rated-Expanding-Foam-can/dp/B0084FNMN0

 

[70datsun]

This question is really a local question as it varies by location. Here you have to uses 5/8 on either the ceiling or the first truss, but not both.

However I would suggest you do both, as it may save your families and your life someday. I would put 5/8 fire drywall on both sides and fire blocking in that common wall as well.

A friend of mine in high school had their ford truck catch fire in his garage (ignition switch). The fire block in the truss saved the house even though it wasn't required.

To save effort they do make expanding fire foam. Use it to seal the perimeter of the truss drywall.

https://www.amazon.com/Fire-Rated-Expanding-Foam-can/dp/B0084FNMN0

Good case for doing both. One question I have pertains to the hozitonal 2x4 braces that now tie in the bottom cord of the trusses, plus some other braces from the common wall that a drywall nailer is attached to. Can I notch the truss drywall around those without taping the edges? Or maybe seal up the edges with some of the foam you're talking about?

 

[pcmeiners]

Check to see if it is type X sheetrock required, regular sheetrock does not stand up to fire well. In NYC a firewall generally consist of 2 layer of type X or better, never just one. You think a garage wall is a pain to firewall, try a warehouse.

 

[Majordisorder]

Just notch the drywall and piece in where you have to. It is common to "fire tape" which doesn't require finishing and is only to cut off air where possible.

 

[70datsun]

Check to see if it is type X sheetrock required, regular sheetrock does not stand up to fire well. In NYC a firewall generally consist of 2 layer of type X or better, never just one. You think a garage wall is a pain to firewall, try a warehouse.

Yeah, plans call for type X, but just a single layer of 5/8. Looks like I'll be drywalling on miniature scale today. It's also sort of a drag because my trusses were engineered for center storage, but now I have to break the attic space. Oh well, best laid plans and all...

 

[readhead]

You can put a rated door with a closer in the attic and maintain the storage space.

The garage and the living space have to be separated. The drywall can be installed vertical or horizontal. I worked on a house one time where they ran 5/8"X board along the top of the attic trusses, got inspection and then sheeted the floor with plywood. The separation has to be there but can take any shape.

 

[brownbagg]

code just required two sheet against the living section and fire blocking to keep attic fires against. not the whole building

 

[ard]

Greetings, I'm building an attached garage that has a small addition (sitting room, pantry, and closets) between the garage and house. The plans call for 5/8 drywall on the garage wall attaching to the house, which makes sense. But it also calls for the drywall up to the bottom of the roof decking, rather than just on the ceiling. Since the nearest truss to the garage wall is offset from the top plate, it's going to be a real pain to drywall, tape and seal all of this. Has anyone encountered anything like this? I would much prefer to just drywall the ceiling!

You can frame a simple wall in the attic, from the top of the lower wall up to the roof deck, so it is all one plane. It isn't a structural wall, just holds the Sheetrock.

How many inches is the 'offset' to the truss?

 

[Rock knocker]

I have heard that 2 sheets of standard 1/2 drywall also meets the requirements of a fire wall

You've heard wrong. This used to be free, but it isn't anymore.

 

[66cj225]

Build a detached garage. It will be bigger and you can get more fun stuff in there.

 

[tez929rr]

We worked garage fire that absolutely destroyed a garage and contents (including a car) and did not spread to the house interior (had a huge common wall with the house).

Anything you do to enhance that firewall could save you a lot of money one day.

 

[DCarr2]

in our old shop, my dad said they used 2 layers of 'failed' fire rated drywall... Not sure if you can still get this stuff anymore...

Essentially theyed run say 1000 sheets and randomly test the drywall. if it failed theyd scrap the whole line.

Dad said they used 5hr drywall, 2 layers.

 

[Firebrick43]

Good case for doing both. One question I have pertains to the hozitonal 2x4 braces that now tie in the bottom cord of the trusses, plus some other braces from the common wall that a drywall nailer is attached to. Can I notch the truss drywall around those without taping the edges? Or maybe seal up the edges with some of the foam you're talking about?

yes. That is why I suggested it. I would not tape the edge or penetration period of the truss, use the foam or a fire stop caulk I would also use the foam to seal the bottom edge of the truss dry wall to the top surface of the ceiling drywall, again not taping. Its more effective that taping.

Beware there are funny play on words with similar products. You need fire stop foam not fire block foam. Fire stop or fire rated passes the ASTM 814 rating. The other good product that matches is boss 813. These are rated for commercial and multifamily structures

Products like great stuff fire block are tested to a ASTM 814 "MODIFIED" standard and while they stop draft that can carry flame and embers they are not very fireproof at all.

I personally when putting up a fire wall on a truss cut the bracing 2x4 off flush with the face of the truss to be firewalled and the adjacent truss that will face it. Then I drywall the face and don't have to deal with notching and wrangling bunch of pieces of drywall. After the drywall is up and fire taped on the seams I cut a rectangular hole into the drywall and slip a 2x4 brace through it and nail the the to the trusses (4 total). yes you have a couple of extra 2x4's but their is much less cussing in the drywall phase.

 

[slow]

How far offset and could you just add an extra truss to line up with the top plate? (No idea if this is an option)

 

[atthebeach]

Check with your local permit office as to what is required in your jurisdiction. In my neighborhood, they only care about the fire rating of walls, not ceilings. The fact that I have a common attic between the garage and the house was of no interest to them. The local official agreed with me that a fire could travel through the common attic to the house, but he went on to explain that our local codes do not address it.