Roof Flashing for Bathroom Fans

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Video Transcript

The roof flashing for bathroom fan needs to be installed correctly, so you do not have a roof leak.

Hi, I am Tim Carter and I want to show you how to install a roof flashing for bathroom exhaust fan and it is not that hard to do. I want to talk a little bit about roof safety. If you are not comfortable working up on a roof, then do not do it. You can fall, get seriously hurt, or you can die. If you want to hire a professional to do the job, no worries, just make sure they follow the same steps when they are installing the flashing so that your roof does not leak.

Let us get started right now.

The first thing to do is to locate the hole that is going to be cut from the inside. The exhaust fan roof vent must exit the roof between two roof trusses or two rafters. I like to drive a large nail through the roof sheeting from the attic side. You will be able to easily see this nail once you go out on the roof. Be sure you are at least 2 feet away or so from any chimneys, roof alleys, or other vent pipes. You want the bathroom exhaust fan vent to be located in the area of the roof with there adjust shingles. Mark the size of the hole with any marker you can see on the shingles. Make the hole slightly bigger than a diameter of the object passing through the roof. Use a reciprocating saw to cut the hole on the roof. It is okay to cut right through the shingles at the same time as you are cutting through the wood roof sheeting.

That was a hard work.

Okay, now, here is the magical part. Now that we have got this big hole cut in the roof, where all the rain can come in. 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.

One shingle overlays another and the upper shingle is always on top of the lower one. Note how part of each shingle is hidden under the shingle above. This flashing is no different than a shingle because notice how, it is a square basically or rectangle just like the shingles and here is what will happen. Notice that we put it on this hole and this part is overlapping the shingles below it but the mistake right now is that the flashing appears is lying on top of this shingles that is no good. We need this row and this row of shingles to be lying on top of the flashing.

To get the flashing up under this shingles, when you do remove some nails from the shingles that lay on top of the flashing. The nails are always located above the knock out slits in these types of shingles. If you lift up a shingle tab, you will either see a nail or sometime you may see a staple. You can easily determine which nails need to be removed by placing the flashing over the hole that was cut out and look in to see where the flashing will be once it slides up under the shingles.

Okay, I am really pretty lucky on this particular roof installation. There is only one nail in our way and it happens to be right here. It is right underneath this shingle. Okay, so I am going to take that nail out and we are almost going to be ready to go here. We will just have to trim a few shingles to finish the job. I use a flat pry bar to gently remove the nails so it is not to damage the shingles. It is better to work on the roof when it is cool to minimize damage to the shingles.

We have got just a little problem here before we continue. I cut a round hole, or pretty round with a sawza and these shingles up above that are going to lay on top of the flashing will, they need to be square cut because look at his, look at this flashing. The top part that actually extends through the roof is square, so it has got these two hard 90s and I would like to keep the shingles about a half-inch away from this side edge of the flashing and the top in the other side. So we are going to have to take some measurements and lay that out and carefully cut the shingles with a razor knife.

When you have a good fit, it is time to nail the flashing into position. Lift the shingle tab on either side of the flashing and drive the nail through the edge of the flashing. You can also drive the nail or two to the lower exposed edge of the flashing but be sure to apply some cock over the nail head to help seal that exposed nail.

I told you it was easy to put in a roof flashing. You can do this job.

I am Tim Carter for AskTheBuilder.com.