"Laminated" Roof

[Brian G]

I just looked at what I'm told is a 110 year old house. Some sections had been stripped down to the skip-sheathing, decked with OSB, and roofed with a single layer of composition shingles. The other sections still had what I think was the original cedar shingles over skip-sheathing with 3 layers of composition shingles on top, including the recent one. Totals about 2 1/2 inches thick. Amazingly, no signs of sagging found on the rafters (rough-cut pine 2 x 4's). If you look across the layered sections, there are lots of little puckers and bumps going on.

Believe it or not, this is the first time I've seen more than 2 layers on a roof (then only 3 times). We had a hell of a storm come through in 2000 that brought damn near everyone a new roof for miles around. So...

What all are the issues here?

Weight of course.

Possible lack of fastener strength reaching through all of that.

Isn't this against all manufacturers' specs?

Does code address it?

Any and all input welcomed.

Brian G.

[DonTx]

Many insurance companies in this area will either not insure a roof with comp over wood shingles, increase your premium or disclaim roof coverage.

The same goes with 2 or more layers of shingles. They know the next time it needs shingles, it'll have to be stripped down to the decking and they do not want to be left holding the bag.

Donald

[Brian G]

Originally posted by Donald Lawson

Many insurance companies in this area will either not insure a roof with comp over wood shingles, increase your premium or disclaim roof coverage.

Interesting. What's the thinking behind that?

Brian G.

[Jim Katen]

Originally posted by Brian G.

I just looked at what I'm told is a 110 year old house. Some sections had been stripped down to the skip-sheathing, decked with OSB, and roofed with a single layer of composition shingles. The other sections still had what I think was the original cedar shingles over skip-sheathing with 3 layers of composition shingles on top, including the recent one. Totals about 2 1/2 inches thick. Amazingly, no signs of sagging found on the rafters (rough-cut pine 2 x 4's). If you look across the layered sections, there are lots of little puckers and bumps going on.

Believe it or not, this is the first time I've seen more than 2 layers on a roof (then only 3 times). We had a hell of a storm come through in 2000 that brought damn near everyone a new roof for miles around. So...

What all are the issues here?

Weight of course.

Possible lack of fastener strength reaching through all of that.

Isn't this against all manufacturers' specs?

Does code address it?

Any and all input welcomed.

Brian G.

I see it all the time. You put your finger on the two big issues: weight & long-term fastener performance.

Yes, comp shingle manufacturers require a solid deck.

Yes, the IRC now allows only two layers of shingles, total.

- Jim Katen, Oregon

[Brian G]

Originally posted by Jim Katen

I see it all the time. You put your finger on the two big issues: weight & long-term fastener performance.

Yes, comp shingle manufacturers require a solid deck.

Yes, the IRC now allows only two layers of shingles, total.

Thank you Lord Jim, that should cover it. I'll be interested to hear the how & why the roofer was willing (or might have even suggested) tearing-off some sections but not others. If the clients want it done and the sellers don't want to pay for it, they may go after the roofer.

Brian G.