How to Install Valley Trim: ABC SL-16® Metal Roofing System

At ABC, we aim to provide you with the installation resources your customers need to complete their building projects. This instructional video will educate your customers on the preparation and installation of valley trim.

Metal valley trim, also known as metal valley flashing, is beneficial because it drains water away from the structure of your metal building which helps prevent moisture damage. When installing metal valley flashing, there are a few things to keep in mind from cutting metal roofing to sealing the flashing.

How to Cut Metal Roofing to Fit Valleys

When cutting your metal roofing to fit valleys, it’s important to use the proper tools. Avoid using anything that will melt the galvalume coating such as a chop saw, torch or abrasive blade.

Cut the panels from the ground instead of on the roof to avoid damaging the roof with the debris.

How to Seal Metal Roof Valley

Best practices for sealing the metal roof valley vary based on the slope of the roof.

Low Slope Roofs (Slope less than 3:12)

Use tape sealant between the valley trim and the panel. Use fasteners to attach the panel to the structure, making sure that there is complete compression of the sealant.

Steep Slope Roofs (Slope greater than 3:12)

Cut the panels at an angle for the valley, then bend the hem end of the panel and hook it with a cleat. This approach is ideal for architectural applications because the fasteners are hidden.

Watch the short video or read the information below to learn more how to install valley trim:

Here you have your eave trim with the continuous cleat hiding it all, but we have a valley, so, we’re ready to put valley trim because this will change the sequence of events for what goes on here.

We have two roof planes here that meet in this valley, and ordinarily on a straight eave we would install the tape seal and the offset cleat right away. In this case, because the sequence of events changes and we need to overlap properly, the valley’s going to be installed. The offset cleat will be installed on top of it and then we can run panel.

Valley Trim Prep

Now we have the eave trim installed with the continuous cleat, and before we put in our offset cleat we need to install the valley pan. This is what we call a “W” Valley. It has the raised V in the center, the raised W. Not all valleys do. This raised section is to keep water, snow and ice from rushing down the roof and skipping up onto the other side. It creates a break and makes sure that water, snow and ice gets channeled to the end of the valley. I’m going to put the valley in place, mark the underside of it and cut it so that it fits nicely where the two eaves join at this inside corner. I’m going to mark the valley and overhang it a little bit. You’ll see at the top that I’ve already cut it to fit the ridge line. Now I’m going to mark the underside and cut it to fit at the eave of the roof, then I’ll mark the underside of the valley, tracing alongside the edge of the eave trim. With that done, I’m going to take the valley to the table, make my cuts and come back so we can install it.

Valley Trim Installation

Now bring in the valley panel that’s already been cut. You can see that the edge of the valley has been cut so that it’s in line with the edge of the eave trim. Between the metal and the valley, we’re going to use tape seal to make sure that water can’t lip itself underneath and roll back up underneath the valley.

We’re ready to put the valley pan in place and put a screw through it temporarily, a little higher up so that we can work on putting our offset cleats in. Something else that I need to take into consideration is the valley and where the panels stop as they come towards the center of the valley. For today’s installation, we’re giving a four-inch reveal here in the valley. To make sure that I stop my offset cleat at the four-inch mark, I’ve made these marks and I know it should stop my offset cleat right along this line.



Contact one of our installation experts for tips on how to install your ABC metal roofing panels.