https://www.RoofingContractorGA.com – Our first episode of Chalkboard chat, where we answer your questions about roofing repairs and replacement of your existing roof.
Today’s question comes from Frank in Covington, GA.
He asked this:
“We’ve had major leaks and will be replacing our roof. What is the best underlayment to prevent the valleys in my roof from leaking?”
It’s a great question… and to answer it… let’s first make sure everyone understands what roof valleys are.
When your roof was constructed, plywood was placed overtop of the roof structure. This is what your roofing materials attach to.
As you can see here, there is a natural seem between the sheets of plywood. This is a common source of water leaks in a roof. To help prevent this, a roofing valley is installed to direct any rain water from this seem, down the roof, and into your gutters.
However, in addition to this seem, water leaks can occur in your roof from several other locations. Let’s look at a few of these.
First, around any chimneys in the roof. Again, a seem exists around the edges of the chimney, which can allow water to leak through your roof. You can see the metal flashing that was installed around the chimney to help prevent the problem.
Next… loose, missing, and cracked shingles are another source. Water can easily get underneath of these shingles, and find it’s way through your roof.
Another common source for roof leaks are around pipes that protrude through the roof. It’s the same scenario, a seem exists around the pipe that can allow water through. So when your roof leaks, what happens?
You guessed it, everything underneath starts to get damaged. You can see the obvious wood rot in this picture, taken from the attic of a home in Covington.
So let’s look at my recommendation for the best underlayment to prevent all of these roof leaks.
First, the roofing contractor should lay down a layer of water and ice shield over the entire roof. This is a membrane made of polyethylene and rubberized asphalt. It creates a solid seal between your roof and any seems or cutouts that are made.
Here you can see a great example of how the membrane works. When a nail is driven to secure roofing materials to your roof, the water and ice shield coats the nail, and prevents any type of opening around the nail hole.
This is the first, most crucial step.
Second, I recommend a double layer of the water and ice guard around the most common areas of roof leaks. This includes any chimneys…
… beside any dormers in the roof…
… as well as the edge of the roof, along the eaves.
Eaves are the part of your roof that overhang the exterior walls of your home.
Finally, I recommend metal flashing be installed for the valleys in the roof. Sometimes roofing contractors simply weave the shingles in the valleys, but I typically find a leak can still occur when it’s done that way. With metal flashing, the water will run nicely down to your gutters, and be taken away by the downspouts on your home.