30# Felt Installation Question

Guest User
4/12/2007
I am about to install a 5-V Crimp Galvalume roof on my house over 1 layer of existing flat shingles (over plywood deck). The manufacturer recommends a layer of 30# felt over the shingles, oriented the same way as the panels. Should I overlap the felt, or just butt it up at the edges? A Lap joint will cause a ridge because the felt is quite thick. I understand that one purpose of the felt is to prevent the granules in the shingles damaging the coating of the panels. Thanks.
Todd Miller
Classic Products, Inc.
4/13/2007
I have never heard of someone suggesting the felt run vertically. I would really question their wisdom in that. Normally overlaps are 4 - 6"
Guest User
4/14/2007
Thanks Todd. That's what my roofing supplier said too. But in Gibraltar's literature for 5-V Crimp which is supplied by Home Depot, they show quite clear pictures instructing vertical runs of 30# felt when installing over shingles. Then they show horizontal runs when installing over plywood deck. I'm not using Gibraltar -that was just some info I had. The underlayment needs to conform to the Florida Building Code 2004, sect 1507.4.5 and I'm having a hard time establishing what that requires. Even the town which issued my permit haven't got back to me on it yet.
Todd Miller
Classic Products, Inc.
4/14/2007
www.fabral.com and www.mtlsales.com both have instruction manuals available online.
Guest User
4/14/2007
Tom, I appreciate the links. Both those sites had much more detailed info than I had been able to find by myself.
Todd Miller
Classic Products, Inc.
4/15/2007
good.
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