Fire blocking in an attached garage?

[aunsafe2015]

Picture shows a 13x22 attached garage bay. House was built in 2010 and fully inspected and approved by the local AHJ, and this open wall was previously drywalled until I removed the drywall today. I'm having the walls spray foamed. All that is above this garage is an inaccessible attic space that couldn't be more than 3-4 feet tall. Only way to access it would be to cut a hole in the ceiling drywall, which I'm actually doing to blow in insulation up there. Below the slab is... Dirt.

Anyways, to the point--Foam contractor said top plate, sill plate, and stud pentrations for wires need to be fire blocked with a fire rated foam.

I know it may vary jurisdiction to jurisdiction, but why would fire block be required at sill plates that are sitting on top of concrete blocks? Or for that matter at the top plate when there is no living space above and no opening from the stud bays to the attic?

Also, is fire blocking something that would be inspected during framing? If so, this framing was already inspected and signed off on when the house was built (it had drywall until I removed it). And I wasn't planning on having this insulation inspected.

Would appreciate any input. I'm not at all opposed to the fire blocking if it's a good safety idea, but I was wondering if the contractor is correct about what is required...

 

[James-W]

The foam contractor is correct, at least he would be correct for around here. This is a relatively new code and was probably not the code when the house was built.

I do not know if you HAVE to conform to the new codes since the house already passed inspection when it was built, but since it isn't very difficult to do I would just go ahead and do the fire blocking according to the current code.

 

[Jonny Rotten]

It does seem odd that fire blocking would need to be on the bottom plate...the coolest least fire "issue" place on a slab building....I'd like to know the reasoning behind making a double sill plate for fire reasons

 

[jbwilkins]

You seal the penetrations at the top/bottom plate to prevent the wall cavity from becoming a chimney and drawing fire/smoke into the attic.....

It’s also an air seal/insulation issue, even with foam there will be voids where air can move, if the top and bottom of the cavity isn’t sealed then you get the same chimney affect with cold/hot air.....

 

[Jonny Rotten]

You seal the penetrations at the top/bottom plate to prevent the wall cavity from becoming a chimney and drawing fire/smoke into the attic.....

It’s also an air seal/insulation issue, even with foam there will be voids where air can move, if the top and bottom of the cavity isn’t sealed then you get the same chimney affect with cold/hot air.....

This seems amazingly excessive...nailing a 2x4 on top of another 2x4 aint exactly sealing anything

 

[PoorOwner]

I believe you can use this stuff
https://www.lowes.com/pd/3M-Fire-Bl...MI_6ip15qT3AIVAsZkCh3gtABNEAQYASABEgIS4fD_BwE

just buy a tube or 2, go at it and move on.

 

[aunsafe2015]

Is the expense so much different to make it all not worth doing the fire prevention as suggested and possibly mandated?
Is it 30 bucks, 300,3000 different?

No, the expense isn't that huge (though they are gouging me on it pretty bad considering the foam will probably cost like $15 bucks for a can). I'd do it myself but the top plate is nearly 12 feet high, and I'm a bit unsteady on a ladder, so I suppose I will just allow myself to be gouged on this one.

I was just concerned that I might be getting gouged unnecessarily. But you folks have confirmed that at least it's probably code required!

 

[23ford]

They are correct and also you may need to put fire rated sheetrock on any wall that is common with the House....

 

[NUTTSGT]

I can't tell you what the code says, but they do get updated and things change. In certain situations, during refits or remodels some are required to make updated changes to conform to newer regulations. We, locally, don't inspect residential new structures when built nor am I one of the inspectors for the dept.

The can of fire block foam is about $10 and the tube of caulk is $5-6. If you're unsteady or don't have the ladder, I'd guess you're paying the contractor to do it. That is unless you have somebody do it for you, kid, neighbor or another family member.

What the contractor is saying about the sill might be slightly off. The code maybe for construction has a space under it like a basement or crawl space but he is just making a practice of doing it everywhere to cover his ***.

 

[Heiny57]

I would think the spray foam would fire rate the wall. It does inside commercial block structures.

 

[jbwilkins]

This seems amazingly excessive...nailing a 2x4 on top of another 2x4 aint exactly sealing anything

We foam the penetrations.....