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SESD | there are pros and cons each way.
Leaving the shingles gives some support to the steel in a hail situation. It can help to lessen the damage of the hail dents. I used to be an owner of a construction buisiness and always stripped the shingles off the roof if I was going to put on steel. That gets alot of weight of the house and allows you to have wood backing on the steel, which is nice. Yes, at the customers request i would put steel over the shingles, but I would strip it out.
Stripping with 1X4, or 2X4-- Always allows you to know your screw was secure. Just make sure the stripped boards are shanked into the rafters, not just the sheating. when going over asphalt with solid sheating underneath, you may just hit the sheating and that can be 1/2" on some older houses which means the screw isn't holding great. Going over wood shingles can be a nightmare. Wood shingles have 1X's underneath and they are gapped. If you hit the gap, there isn't much holding the screw. Wood shingles are fairly brittle and crack when the screw hits, so if that's all thats holding the screw, it's not enough. Also if the screws are in the top part of the exposure on the wood shingles, there is going to be a gap between the steel and the roof(not good), which means the screw may not seal very good. Also asphalt shingles can be a little spongy depending on how many layers there are, which means the screw may not seal good either.
If it was me doing the work on my own house i would strip all the shingles off. But i would highly recommend stripping off the wood shingles and pounding in all the nails(or pull them). Asphalt shingles are a little better for putting steel over if you want to.
hopefully this helps. | |
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Tinning over shingles
