Installing a Cut Valley

In this video, I’m gonna show you how to install a cut valley on your shingle roof. Cut valleys are one my personal favorite ways to properly waterproof a valley. They’re approved by manufacturers and look super clean. There is no flashing needed. You just use a little bit of extra shingles, and if done properly, will outlast the roof and do a great job waterproofing the important areas of your roof.

Determine your primary and secondary slopes

Now, before we get started with the cut valley, you wanna make a determination on which side is gonna be your primary slope. And the way we like to do is the roof that’s larger, is your secondary slope. Because you can imagine, the water is gonna come down here, and you wanna make sure that the water does not get underneath that cut valley. So this will come up first, this roof right here. It is the lower slope, it is also preferred, it’ll come up first. Then we’ll cut these, and this will come on top. At the end of this explanation, I think you’ll get a better idea of what that is, but that’s an important consideration you have to make, and it has to be thought out. Think it through, and have a logical reason of why. Now we can get started with first off, the starter shingles, then get installing these shingles on the main primary field right here. Generally, we wanna go up 12 inches past the valley centerline. Now, in this roof, we might not have 12 inches, which is fine, we can go all the way. But if you have a larger slope, you wanna go past this valley centerline, 12 inches.

4 things to point out

Alright, now that we’ve got our primary field installed, we’re not gonna go all the way up just for this tutorial. We’re gonna show you what we need to right here. And a few things I wanna point out:

1. Install shingles with the usual staggered pattern.
2. Install shingles to go 12 inches over the valley center line.
3. Shingles on higher slope will be nailed down later.
4. Don’t install ANY nails near the valley center line.

Install shingles on the second field

Now one detail that we like to use that varies a little bit from other roofing contractors is prior to installing our shingle on this side, we like to install a piece of shingle that’s parallel to the valley. Now we want to come up from our valley centerline about an inch and a half to two inches, to make sure we allow for proper water flow in this channel right here. Now what this shingle is gonna allow us to do is a few things. First off, that adhesive pad that’s on the back of the shingle is gonna adhere real nicely down and ensure that this shingle is not gonna lift up. Another thing it’s gonna do, it’s gonna provide us with a real clean finish. Any time you hand-cut shingles, you’re never gonna get a perfectly straight line. But this is gonna allow us to get a nice clean line and have a really aesthetically pleasing finish.

Alright, we’re essentially done with this valley already. Obviously, we would continue this all the way up on a real roof, but for this demonstration you’ve seen what you need to. You can see the few details that really matter is leaving a little bit of a runway here. A two-inch, inch and a half-space between your valley centerline, and the edge of these shingles. This is gonna allow proper water flow and down. And you can also see that we use a full piece of shingle, and you can see the clean appearance that this provides. I think it provides for a real nice finish as well as for a great water proofing detail.