Do I need to add a layer of roofing?

I bought a house 1 year ago and found out that the roof decking is 1/4 plywood. I will be replacing the shingles in the next couple years, should I add another layer of roof decking onto the existing decking?

Yes. You should add Proper Sheathing before applying the new shingles. Install ½” or 7/16” Sheathing Material (Plywood or OSB) over the existing ¼” sheathing. This will provide a good solid deck to nail your new shingles to. If it is nailed properly, it will add tremendous Shear Strength to your building. Thank You for your question. We hope it helps.

Your Friends at Ask A Roofer

One last question, could the new 1/2 inch decking be placed on top of the existing shingles or do the old shingles have to be removed first?

The old shingles have to be removed.

Your Friends at Ask A Roofer