What is the screw substitution for cooler nails in Gypsum shear walls? 1

[BLSPAM]

Does anyone have information on the screw substitution for cooler nails in Gypsum shear walls? To make a long story short the IBC 2012 has omitted this information and the Gypsum association is not helpful.

 

[Celt83]

you can view the SDPWS free online at the american wood council website:

https://www.awc.org/codes-standards/publications/sdpws-2015

The screw substitution changes the fastener spacing and in most cases halves the shear capacity of the wall panel for 5/8" gyp.

Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

 

[BLSPAM]

I believe everyone involved would like to use screws at some spacing for the attachment of the 5/8” gyp to the shear walls. But as you know we are running into a snag.

1)2006 IBC table (attached) provided shear values for 5/8” gyp and footnote C allowed for a substitution to drywall screws.

2)2012 IBC omitted this table (replaced with table 2306.3(C) values for stables – no substitution to screws)

3)American Wood Council (table 4.3C) has the shear wall tables. We believe it replaced the 2006 IBC table. The table only has the higher capacities (what we need for this project) noted for nailed shear walls and they do not note the substitution to drywall screws. They do not even have a capacity of a 5/8” GYP panel wall with screws at a 4” spacing, just 8/12 and the capacity is about half of that with nails at 4” spacing.

4)The Gypsum Association literature, GA-229-08, notes shear values for screw application but only at the 8” spacing. These value are less than the values of a ½” panel thickness at a 4” spacing.

5)The ESR-1338 also has values for screws but again, the only screw values in 5/8” gyp is at a 8/12 spacing.

6)The only place we can find a screw for nail substitution is in the GA 600-215 but this from the Fire Resistance Design Manual.


Usually after a little research we find that the substitution is still allowed but we can’t find that in this case.

It’s almost as if the American Wood Council does not want us using GYP shear walls!

If we can’t find a substitution and using nails is not an option we would need to design shear walls to incorporate more OSB/plywood. This will cost the owner more money in materials and engineering.

Does the Gypsum Association plan on any further testing to replicate the 2006 IBC values? This would be worth the effort because as building officials get more familiar with this issue contractors, engineers, and owners will become less happy with the Gypsum Association.

 

[Celt83]

I posed the question to the American Wood Council will let you know what I hear back. We get a lot of push back on the nail requirement as well.

Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

 

[BridgeSmith]

"It’s almost as if the American Wood Council does not want us using GYP shear walls!"

Ya think?

"Does the Gypsum Association plan on any further testing to replicate the 2006 IBC values?"

They should if they don't want to lose market share to the wood panel alternatives.

 

[Celt83]

here is AWC's response:

"The SDPWS assemblies are based on physical testing, so you can’t substitute components and assume the same strength. Since most screws are proprietary, you’ll need to get an ESR or other third-party certification report for that product."

Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering