This may be a simple question, but I just want to make sure I am doing it right. When installing a leaf guard on a gutter under shingles, which layer is best to put it under? I do not know much about roofs so I thought I would ask.
As you can see, there seems to be two layers. Should the guard go under the first or second layer? Thank you.
Since you have three-tab type shingles, I would put it under both layers. If you put it under just one layer the guards will show through in the drip lines. They'll also tend to catch debris a bit more.
Also, the bottoms of each tab are bonded to the layer below with tar strips. By separating them you reduce storm damage resistance slightly.
I am assuming that you are installing a surface tension type of system. Ideally the metal sheet should go under both layers of roof. It is hard to tell from the photo but it appears that the gutter may be high relative to the first roof. If this is the case it will still work if it goes under the top layer only. If the gutter is too high, preventing the gutter guard from laying at the same slope as the roof, you will need to relocate the gutter at a slightly lower position. If the guard does not have enough slope the leaves will get hung up rather than being washed off the roof.
