Dormer Questions

Hey Guys,

I’m a DIY homeowner and have a few questions. I’m finishing up a complete tear off and I saved the face with a dormer for last. I’ll be long-winded, so I apologize in advance. But I thought more information is better.

The dormer pitch is 10, the main roof pitch is 8.

The dormer is oddly shaped, longer on the right side than the left. It runs down farther and blends into the porch roof. So the left side eave is flush with the second story roof eave. The right side eave is flush with a first story roof eave. The outline resembles the number 7 on its side.

For the left side, the main roof is about 200 square feet (minus the dormer foot print) and the dormer is 60 square feet.

For the right side, the main roof is about 408 square feet (minus the dormer foot print) and the dormer is 60 square feet.

Here are my questions:

  1. Which roof do I shingle first, the main or the dormer? I’ve read that you shingle the face carrying the least amount of water first. But then I’ve also read you shingle the lowest pitch first. Or is it a moot point and you always shingle the dormer first?

  2. How do I line up the rows of shingles from one roof to another? I’m fine with the left side because the dormer eave is flush with the main roof eave. It’s the right side that concerns me. Its eave is flush with a lower one-story roof eave. So I’m probably not going to get lucky and the shingles line up when they meet the main roof eave. Do I just trim a little off a few rows until they line up when they meet? The roof is only about2 feet wide between the porch roof and the main roof, so it wouldn’t be noticeable.

  3. Do I install a ridge vent on the dormer? The dormer ridge is 12 feet long and 6 feet below the main roof ridge. The left side of the dormer eave is only 2 feet long and I can’t tell if the soffit if vented. I can verify if needed. The soffit on the other side is about 5 feet long way down at the first story level, but there’s no way for me to tell if it’s vented all the way up through the porch to the ridge.

Thanks guys. I appreciate the help and your expertise!!

Some pictures would help. On small dormers I generally do the dormer first, but sounds like you have a pretty big dormer so that really depends on your roof, pitches, and how much roof is above where it ties in.

In most cases don’t try to make the shingles line up. Start at the bottom shingle to the top. You can think all you want, I tried it when. I was younger, but when you have different pitches and angles they arnt going to line up and you don’t notice it.

Ridge vent is up to you. If you decide to use it start it 1-2’ out from where the dormer ridge intersects the main.

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