Thermal Barrier

[Fritz]

We have been asked to accept 3/4" plywood as be equivlent to 1/2 sheetrock for a thermal barrier.

On face value, section 721, it would appear to be so. But I cannot come across any tested documentation.

I know some roofing assemblies use it as a separation, but that I believe is in a tested assembly.

Any thoughts or directions to go look for some information.

 

[Yankee]

I haven't found it in the section yet,

Seems like the tables as you mentioned are assemblys only.

 

[north star]

$ $ $ $



Fritz,



Since you have been asked to approve the 3/4" plywood as a substitute,

..ask that documentation be provided to you that will allow the

substitution.....( i.e. - where are "they" obtaining their approval from ? )

Isn't the burden of approval on the person asking ?



$ $ $ $

 

[fatboy]

http://www.fpl.fs.fed.us/documnts/fplrp/fplrp408.pdf

Skip to the summary on the last page, 3/4" plywood performs similar to 1/2" gyp.

 

[Yankee]

"The performances

of the 5/8-inch hardboard composite, the

3/4-inch mixed species plywood, the 5/8-inch particleboard,

and the 3/4-inch southern pine plywood were

comparable to the performance of the 1/2-inch regular

​

gypsum board."

Where does it say if that was tested with thte foam backer as accotrding to the same article,

"The presence of insulation behind the

panel reduced the times to achieve a 250°/325° F rise

​

in temperature."

Also, this looks like 1982, , , not that it maybe matters . . .

 

[fatboy]

Wasn't really arguing one way or another. My gut reaction was that it would probably protect in a similar fashion, Googled it, and came up with the report. Not my issue, just adding information.

 

[Yankee]

well I kinda agree has I have been approving "like" barriers without the testing report . . .

 

[mark handler]

A 15/32" Wood sheathing is equal to 1/2" Gypsum Wall Board when you are seeking a 15-Min. Thermal Barrier

 

[Yankee]

A 15/32" Wood sheathing is equal to 1/2" Gypsum Wall Board when you are seeking a 15-Min. Thermal Barrier

how did you come by that?

 

[Francis Vineyard]

Assuming type 5 construction; using 2006 take a look at Section 703.

 

[Yankee]

Assuming type 5 construction; using 2006 take a look at Section 703.

nowhere do I see what you are leading me to?

 

[Builder Bob]

http://www.awc.org/publications/DCA/DCA4/DCA4.pdf