Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Roofing/Siding

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-05-2012, 04:22 AM   #1
Newbie
 
Join Date: Feb 2012
Posts: 1
Share |
Default

Nailing Rigid Foam Boards to Plywood


Live in SF Bay Area (CA) in an Eichler-style house built with a low-sloped, hot roof and no insulation. The existing roof system is composed of (top to bottom) tar & gravel roofing, celotex fiber board, and 3”x 6” exposed ceiling beams placed 24” OC. Plan to re-sheath the beams, add insulation and re-roof.

Would like to install 3/4" structural plywood above the beams, then rigid polyurethane boards/panels (1”-2” thick), followed by external roof (most likely a spray-applied foam). Using closed-cell foam for higher R-values.

My question is how to attach the rigid foam panels to the plywood. Since the plywood’s lower surface is exposed to the interior of the house, the nails can’t penetrate the plywood or else they would be visible. Full nailing depth is limited to areas where the nails are located immediately above the beams.

How do I secure the rigid foam panels to the substrate and stay within building code for fasteners and nailing patterns to plywood sheathing. Are nails allowed to "not" penetrate the structural plywood and is there a minimum nailing depth?

Buscador is offline   Reply With Quote
Old 02-05-2012, 06:59 AM   #2
Member
 
Join Date: Nov 2011
Location: Hartfield VA
Posts: 25,820
Default

Nailing Rigid Foam Boards to Plywood


Instead of plywood, concider using T & G 2 X 6's or 8''s.
Much stronger, will look far better from the bottom side, added R value and will give you far more thickness for fastening. Most often the foam is screwed down with special screws with phillips head screws and fender washers built right onto the the screws. Any real roofing supply will have them.

joecaption is offline   Reply With Quote
Old 02-05-2012, 08:19 AM   #3
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: VA, MD, DC
Posts: 5,655
Default

Nailing Rigid Foam Boards to Plywood


Quote:
Originally Posted by joecaption View Post
Instead of plywood, concider using T & G 2 X 6's or 8''s.
Much stronger, will look far better from the bottom side, added R value and will give you far more thickness for fastening. Most often the foam is screwed down with special screws with phillips head screws and fender washers built right onto the the screws. Any real roofing supply will have them.
+1

Great advice.

You may want to consider covering the T&G board with a peel and stick ice/water shield for proper air seal as well.
Windows on Wash is offline   Reply With Quote
Old 02-05-2012, 08:30 AM   #4
Member
 
Join Date: Feb 2012
Location: Utica, NY
Posts: 514
Default

Nailing Rigid Foam Boards to Plywood


First, don't apply the foam under the plywood but on top of the plywood.

That is the accepted practice and really can't figure out how to do the foam first.
framer52 is offline   Reply With Quote
Old 02-05-2012, 09:05 AM   #5
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: VA, MD, DC
Posts: 5,655
Default

Nailing Rigid Foam Boards to Plywood


If you don't care about the T&G look, look for something called nailbase.

There are several manufacturers that make it and it will simplify your installation.
Windows on Wash is offline   Reply With Quote
Old 02-05-2012, 06:22 PM   #6
Member
 
Join Date: Jun 2011
Location: Atlantic Canada
Posts: 377
Default

Nailing Rigid Foam Boards to Plywood


Strange to put down foam and then spray. Why not just put down 4" of foam and a membrane (EPDM, PVC, TPO...). These can be adhered with glue.

shazapple is offline   Reply With Quote
Reply

Tags
fasteners, foam board, plywood sheathing


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Insulating Basement w/ Rigid Foam and Batt Reilley Building & Construction 4 08-03-2013 10:07 PM
expanding foam vs cutting sheets of rigid foam for rim joists Red Squirrel Building & Construction 15 11-23-2010 11:46 PM
Covering rigid foam insulation in furnace area looking4ideas Building & Construction 4 12-30-2009 05:49 AM
Rigid foam Install in Basement Chasester Building & Construction 8 12-16-2009 08:07 AM
Rigid foam as floor insulation rkhpapa Building & Construction 3 09-24-2006 06:06 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.