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The roof flashing for a bathroom fan needs to be installed correctly so you don't have a roof leak
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Hi, I'm Tim Carter and I want to show you how to install a roof flashing for a bathroom
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exhaust fan and it's not that hard to do. I want to talk a little bit about roof safety
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If you're not comfortable working up on a roof, then don't do it
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You can fall, get seriously hurt, or you can die. If you want to hire a professional to do the job, no worries
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Just make sure they follow the same steps when they're installing the flashing so that your
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roof doesn't leak. Let's get started right now. The first thing to do is to locate the hole that's going to be cut from the inside
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of the attic. The exhaust fan roof vent must exit the roof between two roof trusses or two rafters
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I like to drive a large nail through the roof sheathing from the attic side. You'll be able to easily see this nail once you go out on the roof
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Be sure you are at least two feet away or so from any chimneys, roof valleys, or other vent pipes
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You want the bathroom exhaust fan vent to be located in an area of the roof where there are just shingles Mark the size of the hole with any marker you can see on the shingles Make the hole slightly bigger than the diameter of the object passing through the roof
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Use a reciprocating saw to cut the hole in the roof. It's okay to cut right through the shingles at the same time as you are cutting through
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the wood roof sheathing. whew! That was hard work. Okay, now here's the magical part
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Now that we've got this big hole cut in the roof where all the rain can come in
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I think you need to understand exactly how shingles work so that you can see why this flashing is not going to leak once I install it
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One shingle overlays another, and the upper shingle is always on top of the lower one
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Note how part of each shingle is hidden under the shingle above
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This flashing is no different than the shingles, because notice how it's a square, basically, or a rectangle, just like the shingles
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And here's what would happen. Notice how we put it in this hole, and this part is overlapping the shingles below it
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But the mistake right now is that the flashing up here is laying on top of these shingles That no good We need this row and this row of shingles to be laying on top of the flashing To get the flashing up under these
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shingles, we need to remove some nails from the shingles that lay on top of the flashing
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The nails are always located above the knockout slits in these type of shingles. If you
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lift up a shingle tab, you will either see a nail or sometimes you may see a staple
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You can easily determine which nails need to be removed by placing the flashing over the hole that was cut out
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and looking to see where the flashing will be once it slides up under the shingles
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Okay, I'm really pretty lucky on this particular roof installation. There's only one nail in our way and it happens to be right here
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It's right underneath this shingle. Okay, so I'm going to take that nail out and we're almost going to be ready to go here
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We'll just have to trim a few shingles to finish the job. I use a flat pry bar to gently remove the nails so as not to damage the shingles
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It is better to work on the roof when it is cool to minimize damage to the shingles
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We got just a little problem here before we continue I cut a round hole or pretty round with the saw and these shingles up above that are going to lay on top of the flashing well they need to be square cut because look at this look at this flashing
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The top part that actually extends through the roof is square. So it's got these two hard 90s
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And I'd like to keep the shingles about a half inch away from this side edge of the flashing and the top and the other side
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the other side, so we're going to have to take some measurements and lay that out and carefully
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cut the shingles with a razor knife. When you have a good fit, it's time to nail the flashing into position
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Lift the shingle tab on either side of the flashing and drive a nail through the edge
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of the flashing. You can also drive a nail or two through the lower exposed edge of the flashing, but be sure
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to apply some cock over the nail head to help seal that exposed nail
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I told you it was easy to put in a roof flashing. You can do this job
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I'm Tim Carter for Ask the Builder.com
