Roof leaks in McAllen almost never start where homeowners expect. The shingles look fine from the driveway, the roof is only a few years old, and the ceiling stain only shows up after a hard rain. When we get on the roof, the cause is usually the same thing: nails driven in the wrong place.
One nail is enough
A shingle is meant to be fastened in the nail zone, where the next course covers the head. Drive a nail too high and it sits exposed in the gap between courses. Drive it too hard and it cuts through the mat. Either way the head is out in the open, and in a valley — where water from two roof planes funnels together — that head sits directly in the path of everything running off the roof. Water hits the nail, follows it down, and gets in behind it.
On the house in our video we found exposed nails one after another in the same valley, right above the room where the homeowner was getting water over her windows.
Pull-through: the nail backs out on its own
Valley heat and moisture make roof decking expand and contract every single day. A nail that was seated badly works loose through that cycle until the head lifts above the shingle. Roofers call it pull-through. On camera, Juan pulled one out of the shingle with his fingers — no tools. Every one of those is an open hole waiting for the next storm.
Why nobody catches it
This is the part that costs homeowners the most. A poorly nailed roof looks identical to a good one from the street. The homeowner is happy, the neighbor asks who did the work, and the same crew installs the same mistake down the block. By the time the leaks show up, four or five houses in the neighborhood have the same problem — and the installer was never trying to cut corners, he just never learned to place a nail correctly.
The second thing we check: pipe boots
After nails, we check flashing — especially pipe boots, the rubber collars sealing the vent pipes that come through your roof. Rubber boots dry out, crack and break apart, and in the Rio Grande Valley sun they give you about five or six years, not fifteen. Once that seal fails, water runs down the outside of the pipe and into the decking. We have cut out sections of plywood rotted straight through around a vent pipe, while the ceiling below still looked fine.
A lead boot costs more and will never rust, crack or corrode. Installed and sealed properly, it outlasts the roof.
Underlayment is your backup
If water does get past a nail, the underlayment is the only thing between it and your decking. Old black felt paper does not move with the wood, so it tears around the fastener and leaves a gap. A quality synthetic underlayment expands and contracts with the deck and keeps that nail sealed. When we see a roof nailed as badly as this one, we assume the underlayment is cheap too — and usually there is no starter strip either — which is what rots out the soffit and fascia a few years later.
What to do if your roof is leaking
- Call a certified roofer and have them come out at the right time of day, when the light shows the roof plane clearly.
- Have them check the valleys and lift shingle tabs, not just look from the ridge.
- Have them check every pipe boot and all the flashing.
- Ask what underlayment is under there, and whether a starter strip was used.
- Get photos of anything they find, so you can see it yourself.
Watch the whole walkthrough here: Roof leak in McAllen? One nail in the wrong place is usually why.
We will come look at it for free
A free roof inspection in McAllen takes under an hour and you get photos of whatever we find. If there is damage, see roof repair in McAllen or storm damage roof repair, and if a storm caused it, here is how roof insurance claims work.
Frontline Roofing — McAllen, Mission, Edinburg and the Rio Grande Valley. Call (956) 586-5711.