Asphalt Shingles over Cedar Shakes—Good Idea or Bad Move?

“I have asphalt shingles over wood shakes. I would like to remove the old asphalt shingles and install new asphalt shingles directly over the wood shakes. There is no sheeting under the shakes. Can I do that?”

blog-shingles-cedar-olsage-smI have heard of this being done but have never seen asphalt shingles being installed over shakes and I would certainly not recommend doing that. I can’t visualize the shakes being flat enough to install asphalt over them. I have read where insurance companies will not insure homes with that kind of roofing so that is something to consider as well.

The asphalt will no doubt have conformed to the shape and bonded themselves to the shake and I would think that getting those off without damaging the shakes would be nearly impossible. If you could get them off, any damaged shakes would certainly be leaving the potential for water to get in and you sure don’t want that.

I would suggest that you take both the asphalt and shakes off and install new structural sheathing. You didn’t indicate the rafter or board/slat spacing so be sure to install sheathing with the proper span rating. Installing the new sheathing over the boards/slats used for the shakes may be an option, assuming they are in good condition. Be sure to install the sheathing with the strength axis perpendicular to the supports and space the panels 1/8 inch apart. Then follow the shingle manufacturer’s and building code requirement for roofing paper and install your new shingles.

If this is a large area or there are hips and valleys to contend with, I think it would be wise to consult a professional roofer or your local building official so water penetration issues aren’t created.

I hope this helps you and good luck with the project.

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