Prevent Rot in Cedar Roof Shingles

Learn how to prevent rot in cedar roof shingles. Find out what kind of underlayment to apply beneath cedar roof shingles.

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LESLIE: Listening on WPRO in Rhode Island is Tom who’s working on the outside of the house. What’s going on?

TOM IN RHODE ISLAND: I have a white cedar shingle roof and it’s about 25 years old and just about need of replacement right now. My question is there’s a lot of controversy about using white cedar shingles or red shingles.

TOM: Mm-hmm.

TOM IN RHODE ISLAND: On top of the roof, we have plywood; no tar paper or underlayment.

TOM: So you’re cedar shingles are nailed right to plywood?

TOM IN RHODE ISLAND: Yes, they are.

TOM: That’s a rotting situation waiting to happen. It’s completely wrong.

TOM IN RHODE ISLAND: The nails corroded and they’re causing the shingles to rot right out.

TOM: Yeah, that’s just – it’s just all wrong. That’s just not – that’s not the way you install a cedar shingle roof. You have to put cedar shingle roofs on lath. You basically have to put strips of wood across the rafters and then you nail the shingles to that and they have to be exposed to the air below and above. If you nail cedar shingles to plywood like you would an asphalt shingle, you’re basically creating a moisture sponge that’s going to rot the shingle or rust the nail or cause mold and moisture damage. And so it’s – it was done wrong to begin with.

So now that you’re going to take these off, are you committed to putting a wood roof back on or would you consider a, for example, a dimensional shingle that sort of looks like cedar?

TOM IN RHODE ISLAND: Actually, wood roof.

TOM: Alright. Well, if you’re going to do that, what you’re going to probably have to do is pull the plywood off and put a – put wood lath on. Because you can’t go on top of the plywood. You just can’t do it. And if you don’t take it off and put wood lath strips on, it’s going to rot once again and you’re going to get a roof that’s going to last you like five or six years. And you know, that’s a lot of money to spend on a roof that’s only going to last you a few years.

Tom, thanks so much for calling us at 888-MONEY-PIT.