Code Required Roof Sheathing Bonded by Exterior Glue 1

[JoshH726]

Interesting comment I received from a local reviewer for a small single-story wood frame building:

"MBC(2015 Michigan Building Code)2304.8.2 [IBC2012 2304.8.2]. Structural roof sheeting(sp). Glue top chord to underside of sheeting(sp)." Has anyone seen this enforced, done, etc?

Conversely, APA's "Engineered Wood Construction Guide (E30W, 2016) page 69 states "Note: Gluing of roof sheathing to framing is not recommended, except when recommended by the adhesive manufacturer for roof sheathing that already has been permanently protected by roofing". I spoke to APA about this already today, and I'm waiting to hear back as this would not be their recommendation either.

Anyone else have thoughts or experience with this? Thanks in advance.

 

[JAE]

Have never used glue on roof sheathing in over 30 years. Why would you?

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[JoshH726]

Exactly, but why is it in the code then? And how can you argue otherwise if it's in the code?

 

[MotorCity]

Its worded a little differently in IBC 2015:

" Wood structural panel roof sheathing shall be bonded by exterior glue"

Perhaps it means that the individual plies of the plywood should be bonded together using exterior glue (not bonding of the plywood to its supports).

 

[JAE]

Are you talking about this sentence (taken from the 2015 MBC):

That is talking about the glue that is used to fabricate the sheathing itself. Not glue used to fasten sheathing to other structural members.



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[BridgeSmith]

Perhaps the perceived discrepancy is related to prohibiting the use of glue alone to attach the roof sheathing, i.e. you can use glue and screws or nails, but you can't use glue instead of screws or nails.

Subflooring is often put down with both, especially if nails are used, to prevent squeaky floors.

 

[Tmoose]

The online copy of 2015 2304.8.2 matches what JAE posted.

https://up.codes/viewer/michigan/mi-building-code-2015/chapter/23/wood#2304.8.2

Is the OP's truss related quote from some other section ?

 

[BridgeSmith]

It seems the "local reviewer" that the OP quotes misunderstood the provision.

 

[JoshH726]

HotRod, I believe that is also the case and I agree with JAE.

 

[jayrod12]

I could only imagine the outrage by roofing contractors having to replace rotten sheathing that has been glued down.

 

[BridgeSmith]

You know roofing contractors that actually replace rotten sheathing, jayrod? We don't have any of those around here.

 

[GC_Hopi]

JAE is correct, see 2304.6 It is spelled out a little better for walls.

 

[jayrod12]

You know roofing contractors that actually replace rotten sheathing, jayrod? We don't have any of those around here.

Ha. Sooner or later they need to just to be able to fasten the roofing down..

 

[BridgeSmith]

"...just to be able to fasten the roofing down.."

...assuming they care whether the roofing is actually fastened down...

 

[dhengr]

JoshH726:
This is just another example of the people playing God and in charge of interpreting the bldg. codes for the community, don’t know the codes, their history or their intent, but they sure can be a royal pain in the butt. We do have to know the code, its history and intent in considerable detail, so as to be able to defend our design form this kind of b.s. There should be some way to back charge these jerks for the time they cost us.

 

[msquared48]

My question to the reviewer would be, do they still require ply clips between the panels for expansion now due to the presence of the glue that restricts any panel movement and encourages panel buckling?

Obviously the glue was between the plywood plies and for exterior use. Standard verbage here for many years.

Further proof that plan reviewers need to leave the engineering to the engineers.

Mike McCann, PE, SE (WA)