Composition Shingles Over Wood Shingles

[dtontarski]

First off, my apologies for posting and running. I'm between inspections and I've been called back to look at a roof I inspected earlier this week.

The home was advertised with a "new tear off roof". I inspected the home (1944 built) and discovered the original wood shingles and another layer of composition shingles on at least a portion of the roof. I've always thought that a tear off implied down to sheathing and beyond that it just wasn't a good idea to put composition shingles over old wood shingles. I've been asked to meet all parties tomorrow morning at the home. If I could get some opinions on what the definition of a tear off is and on the appropriateness of covering wood shingles with composition I'd really appreciate it.

Thanks.

Dave Tontarski

NYS Finger Lakes Area

[Chad Fabry]

Don, if there are wood shingles then there are probably at least three roofs to tear off. When they're torn off, the roof will need to be sheeted. Around here that'd run around 400-600 per square with an average quality shingle.

A tear off is down to skip sheathing or down to plywood.

It was allowed to install asphalt shingles over wood shingles. It was not allowed to install asphalt shingles over wood shakes.

[hausdok]

I'd be willing to bet that more than half the housing stock in Seattle is 2-3 layers of comp on top of wood shingles. Wood shingles were the norm around here into the 60's and very few roofs were torn off before they started roofing them over with comp. The only thing that's really bad about them is that most of them haven't been rimmed with one-by and nobody used drip edging here. Consequently, those wood shingles tend to rot out over the gutters while the rest of the deck remains fine.

I've never heard of tearing off down to the cedar deck. That just doesn't make sense. Around here, a tear-off is right down to the skip or to the sheathing.

OT - OF!!!

M.

[dtontarski]

Mike & Chad -

Thanks for the responses. Seems like we have unanimity on what a tear off is.

Chad - you said it "was" allowed to install asphalt over wood shingles....past tense?

Did this change at some time?

The only reason I ask is that I spoke to a local inspector and he was saying that he's heard roofers quote partial tear-offs -down to the wood shingles. I'm with Mike...other than helping the roofer get the bid....this just doesn't make sense.

So Chad...as far as you know....would this described "partial tear off" be allowed in the Rochester NY area today? If so, it seems like the MLS should say "partial" tear off.

Anyway....I got let off the hook...the current owner climbed up on the roof and said....hey you know what....that engineer (that would be me I guess LOL) was right....I got ripped off.

Thanks again.

[Chad Fabry]

Hi Don,

As far as I know, installing comp shingles over wood shingles is still allowed. I said "was" because all the roofs that cedar shingles have had comp overlays for at least 50 years.

It wasn't ever, and still isn't a good practice

[Tom Corrigan]

Chad,

From the IRC:

R907.3 Recovering versus replacement.

New roof coverings shall not be installed without first removing existing roof coverings where any of the following conditions occur:

1. Where the existing roof or roof covering is water–soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing.

2. Where the existing roof covering is wood shake, slate, clay, cement or asbestos–cement tile.

3. Where the existing roof has two or more applications of any type of roof covering.

4. For asphalt shingles, when the building is located in an area subject to severe hail damage according to Figure R907.3.

Some local AHJ's use #1 above to prevent any layover.

Tom C

[Chad Fabry]

Thanks Tom,

So, installing comp shingles over wood shingles is still allowed.

[Tom Corrigan]

Chad,

In NYS, and also in other IRC States, if the AHJ says OK!

Tom C