Flat Roof Replacement in San Antonio, TX

Say "flat roof" and people picture a warehouse. In older parts of San Antonio, though, they're all over houses. You'll find a back porch somebody enclosed in the 1970s, a carport that became a garage, a den tacked onto a ranch house with a roof too shallow to see from the curb. Small shops, offices and corner stores have them too. So flat roof replacement in San Antonio turns out to be a residential job more often than not. And none of these roofs is really flat. They're low-slope, and the amount of slope decides whether one lasts 20 years or leaks every spring.

The ones we replace usually have the same backstory. Someone rolled out cheap roll roofing because it went down fast. Later came tar over the leaks, then tar over the tar. When we finally get the call, there can be three layers up there, a soft spot by the house wall and a brown stain on the ceiling inside. One more patch won't do it. That roof has to come off.

Standing water does most of the damage. Under the International Residential Code, most membrane roofs need at least a quarter inch per foot of slope, and mineral-surfaced roll roofing needs a full inch per foot. Plenty of porch and addition roofs around town have less, or they had enough once and sagged. Water ponds, bakes in the sun, cooks the asphalt and works into every seam. Then hail comes along. KENS 5 reported stones up to 4.5 inches in Helotes during the April 12, 2016 storm, and that storm cracked a lot of these little roofs that nobody noticed until the next rain.

The tie-in is the other weak spot. That's the joint where a low-slope roof meets the shingled main roof or the house wall. All the water off the big roof dumps onto the small one right at the place where two materials meet. A smear of roof cement there won't last long. Get the slope right and rebuild that joint, and you've done most of what makes a flat roof replacement last instead of leaking again in two years. Skip it, and new material over a bad slope is just a newer roof that still holds water.

1. Measure and probe. A level tells us the real slope. We look at the deck from underneath when we can get to it and mark the wet spots before we price anything.
2. Tear off everything. Every layer comes off, down to the deck. Soft or rotted decking gets cut out and replaced at the same thickness.
3. Build the slope. Some roofs get tapered insulation. Some need a cricket to split water around a wall, or new sleepers on the framing to give real fall toward the edge.
4. Install the membrane. On most porches and additions that's granulated modified bitumen, which takes foot traffic and is easy to patch later. Bigger sections usually get white TPO, since a reflective surface keeps the room under it cooler.
5. Flash the tie-in. Membrane goes up the wall or under the bottom courses of shingles, with new step or counter flashing. On a shingle roof we lift those courses and relay them so every overlap faces downhill, the way the water moves.
6. Edge and drainage. New edge metal, and a gutter or scupper sized for the water that roof really collects.

Permits aren't usually a headache. If the pitch stays the same, the City of San Antonio's Development Services Department issues a re-roof permit over the counter. Change the pitch and it goes through additional review. We pull whichever one your address needs, suburban cities with their own rules included.

This page is for low-slope roofs on homes, additions and small buildings, where the flat part is one piece of a bigger house or a modest shop. A building that's flat end to end is another story. Once the roof runs to thousands of square feet and the questions turn to rooftop units, insulation values and whether the old system can stay under a recover, it goes to our commercial flat roofing crew and our commercial roof replacement process. Want to read up on the membranes themselves? See the TPO roofing and modified bitumen roofing pages.

A lot of our flat roofs get replaced during a full shingle roof replacement. Honestly, that's the best timing, because we can rebuild the tie-in from both sides in one go. If hail is why you're looking, our in-house former adjusters can document both roofs on one insurance claim. You can browse the rest of our roof replacement options, or request a free estimate and tell us which part of the house is leaking.