Modified Bitumen Roofing in San Antonio, TX

Climb onto the flat roof of a San Antonio strip center and odds are you'll be standing on modified bitumen roofing. Mod-bit, as everybody in the trade calls it, is asphalt blended with rubber (SBS) or plastic (APP), and that blend is why it stays flexible through a cold snap and doesn't slump in August. It goes on in two or more plies. Reinforced base sheet first, then a cap sheet with mineral granules facing up.

The granules are the wear layer. Keep them on and the asphalt underneath lasts.

You can install it three ways. APP gets torched as it rolls out, the "torch-down" roof most folks picture. SBS can be set in cold adhesive or come as peel-and-stick, so nobody's running an open flame over a wood deck or above a dining room full of customers. We do all three, and we pick by building, not by habit.

So when does it beat a single-ply sheet? When people walk on the roof. A granulated cap sheet takes boot traffic and the odd dropped wrench that would punch through a thin membrane. If you've got a big open warehouse roof nobody visits, though, TPO roofing is faster to install and more reflective, and we'll say so. Our flat roofing and flat roof repair page compares the two if you're still deciding.

Where we usually reach for modified bitumen roofing in San Antonio:

• Restaurants and retail with rooftop HVAC, exhaust fans and grease traps that get serviced every month.
• Roofs crowded with pipes, curbs and drains. Asphalt flashing wraps each one without a welded corner.
• The flat porch, carport or addition on a 1950s or 60s house here, where there's often mod-bit up there already and mixing systems makes no sense.
• Repairs and tie-ins on mod-bit that still has life left.

Old mod-bit tells on itself. The granules wash off, and the bare asphalt cracks into a scaly pattern roofers call alligatoring. Blisters pop up where moisture got trapped. Seams open. Flashing splits where a pipe or curb moves a little every time the building heats and cools. Put all that on a roof with only an inch or two of fall, let a summer storm leave water sitting for days, and it gets worse fast.

Then there's hail. On April 12, 2016, stones up to 4.5 inches came down in Helotes, and that storm was the costliest hail event in Texas history at the time. Five years later, the April 28 to May 1, 2021 event sent baseball-size hail through the middle of the city along I-10, and nearby Hondo picked up a state record 6.4-inch stone. Mod-bit handles hail better than thin single-ply. But once the granules on a cap sheet are crushed off, it's lost its sun protection, and that's insurance damage even if nothing's leaking yet.

A worn mod-bit roof doesn't always have to come off, either. With a dry base sheet and dry insulation, we clean and prime the spot and torch or cold-apply a patch over the blister, split or open lap. If the whole field is tired but the base is sound, a new cap sheet costs a fraction of a tear-off. Wet insulation is different. We probe for it during the estimate and we won't cover it up. Leaks around HVAC curbs and drains go to our commercial roof repair crews.

Storm damage? Our in-house former insurance adjusters document it, get on the roof with your carrier's adjuster and go through the scope line by line, backed by 30+ years of insurance claim experience. The six steps are laid out on our insurance claims page. Marco P. wrote in his Google review: "Came out for the estimate Friday, had a guy on site the next day! 100% satisfied with the quality of work."

We're based in San Antonio and do modified bitumen work across Bexar County and the counties around it. Jobs in Travis and Williamson County go through our Austin line. Here's roughly how an install goes:

1. Inspection and moisture probe. We walk it, probe for wet insulation and look at the deck from underneath if we can get there.
2. Tear-off or recover. One dry layer over a sound deck can often be recovered. Wet, layered or rotted means it comes off.
3. Insulation and base sheet. Polyiso gives you slope and R-value, and the base sheet gets fastened or glued over it.
4. Cap sheet. Torched, cold-applied or self-adhered, with every lap rolled and checked.
5. Flashing. Curbs, pipes, drains, parapets, and the line where a shingle slope meets the flat part, like in the photo up top.
6. Final walk. Laps get a second look, we run magnets for loose fasteners, and you get the paperwork.

Because we run 8 full crew teams, a commercial mod-bit job isn't stuck waiting behind residential storm calls. Texas-RRR is veteran owned. Charlie, our owner, has put in 30 years on roofs, many crews have been with us for over 20, and we've finished 2,800+ projects. We prefer Owens Corning and GAF, and we're registered and insured. You'll find all our low-slope and steep-slope work under commercial roofing. Call (210) 802-6906 or request a free estimate, and somebody will come look at the roof.