Im about to reroof my house with architectural shingles. I have two friends who do roofing telling me different things. One of them says i need to put down some 3/8 osb on top. The other is saying as long as i measure and make sure the nailing strip on the shingles doesn’t line up with the gap ill be good. Obviously i dont want to spend the extra $600 on osb if i don’t need to. But i dont want to have a leaking roof either. Im going to be using ice and water shield and underlayment as well. Im just looking for some feedback.
Replies
I would skip the layer of OSB. More weight.
Just nail to the shiplap?
3/8" osb would add about 1.2# psf to the load. Some basic checking on your rafter sizes/spans should tell you if that's likely to be an issue. To me it does not look like ship lap but square edge boards with cracks between. If so and you can miss all the cracks with nails it'll be ok but any nail in a crack will most likely work back out and eventually through the shingles into plain air. Missing all those cracks might or might not be reasonably achievable. If it matters, the warranty on the shingles would probably be voided due to the square edge decking but shingle warranties are mostly just words on the wrapper anyway.
Create story poles for each section of roof to determine if your roofing nails will indeed line up with the spaces between the boards for what I assume will be a standard 5" reveal on architectural shingles. If you have a problem, either adjust the reveal for all the shingles to achieve the desired outcome on that section of roof, or consider nailing a "problem row" a bit higher than normal, but just enough to nail into solid wood.
For a steep pitch roof, nailing "high" is problematic. We've all seen architectural shingles on a steep pitch roof that have the top lamination of the reveal falling off...
Check the manufacturers' specifications and installation instructions, and specifically look at the width of the nailing zone to see how much leeway is available to you. Pick a shingle product with the largest nailing zone...
your suggestion is very helpful
If you hand nail the shingle you know when you've missed the board and set the nail in the gap. It's alittle more work but work the piece of mind.
I hope this isn't just my ego talking but I disagree. Back a 100 years ago when I did a li'l roofing with a hatchet it was 7/8" nails, you tapped lightly to set and finished with a sharp blow. 4 nails in your off hand lined up between the fingers to finish a shingle, then you position the next one.
It set the nail whether it hit a crack or a good board.
Whether it's a lot more work to hand nail or not idk but I've done a bit of roofing in my old age that I couldn't have done back in the day.