Maybe someone can help, i have a flat roof with no slope, I am rebuilding to 1/2″ per foot, with a new deck.
We have considerable snowloads here, and this will be subject to minimal foot traffic other than to clean gutters/ clear roof.
Should i build it with tongue and groove or spaced joints? either way it will be 5/8 ply with a membrane.
Guidance would be appreciated if anyone has some insight on this.
Replies
First impression is 3/4"t&G
Depends a little on what kind of roof surface material you will be using but you don't want sheets moving independently at the joints is why the T&G.
there are various homasote type underlayments for the different roofing products to help keep it from splitting at that joint, amoung other things.
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Thanks, that was my impression, I dont want any movement at the joints. You think 3/4 is necessary thou?
You did say snow load.
Lots of places, it is hard to get T&G in anything less than 3/4".
Excellence is its own reward!
I did indeed say snow.
5/8 T&G is very readily availible in OSB and Spruce here.
I was thinking 5/8 as a snow load is a very uniform load and the roof joists would be reponsible for the brunt of it.
OSB has come along way whats your take on it for this application?
Advantech OK but I still don't use it on roofs. Regular OSB thumbs down.
One reason I avoid it on roofs is that for hand nailing shingles, it is denser and harder to set into. Another thing is that roof sheathing is subject to high heat stress and I'm not sure what the long term results on the adhesives in the OSB are.
Example - there was a time that fire resistant plywood went into a lot of roofs - until they discoverd that the chemical that did the fire-resisatence thing also reacted in the heat of the attic to delaminate the plys and turn the sheathing into kindling..
Excellence is its own reward!