×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Fire Treated / Resistant Plywood as Roof Sheathing

Fire Treated / Resistant Plywood as Roof Sheathing

Fire Treated / Resistant Plywood as Roof Sheathing

(OP)
Does anyone know limitations of using fire treated plywood as non structrual sheathing on a roof?  

An architect is saying he needs to use plywood on top of my structural metal deck/metal trusses in order to fasten his roofing.  He says the sheathing must be fire treated.  I've never used a system like this and dont know if it'll eat the deck, etc.  Looking on APA, there isnt much info about it.

RE: Fire Treated / Resistant Plywood as Roof Sheathing

(OP)
!!!! Dang !!!!!

RE: Fire Treated / Resistant Plywood as Roof Sheathing

Why don't the architect just isolate it from the deck? Lay a sheet of visqueen down.

RE: Fire Treated / Resistant Plywood as Roof Sheathing

(OP)
Visqueen may help the corrosion problem, but it appears there may be some problems due to solar heating that make FRT wood degrade.

RE: Fire Treated / Resistant Plywood as Roof Sheathing

Solar heating in addition to moisture.  I guess if you can ensure that it remains dry there shouldn't be a problem.  

RE: Fire Treated / Resistant Plywood as Roof Sheathing

Where is the insulation for your roof?
There is nailable insulation that allows the attachment of other materials.

For fire treated plywood, you have to go to treaters web site or get information directly from them.  Plywood manufacturers don't do the treating.

The treatment does affect the structural properties of the plywood, but I am not sure about how it affects attachments or metals in contact with it.

RE: Fire Treated / Resistant Plywood as Roof Sheathing

SperlingPE is on the right track. You could use nailable insultion if it can handle the loading or use 1/2" thick fiberboard insulation (any insulation that would melt in a fire is not acceptable) as a barrier between the metal deck and the FRT plywood, BUT you must check the fasteners because they too can be damaged by the FRT.  

You can use "Deck Mate" screws by Phillips Fastener Products as one solution in FRT lumber, for others go to www.treatedwood.com for listings of other products.

RE: Fire Treated / Resistant Plywood as Roof Sheathing

Fire treated plywood is especially prone to rot without proper ventilation.

In a code seminar I recently attended I heard of a townhouse project (somewhere on the East coast? can't remember) where the attics where not properly ventilated and the rot required a complete re-building of the roof sheathing after something like 5 to 7 years.

A quick google search on the subject turned up;
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr62.pdf

Of course this might be more an 'architectural' issue, but you might want to consider it in your design.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources