Flat Roof Replacement in Austin: what we actually do
Flat roofs in Austin live and die by the seam work, the drainage, and the flashing details at every penetration. Twenty-seven years of work on Central Texas flat and low-slope roofs means we know what fails first on each system. Modified bitumen seams that were rolled cold instead of hand-torched. TPO membranes mechanically attached where the building required fully-adhered. Torch-down feathering rushed by a crew that did not understand the difference between hot enough to bond and hot enough to leak through.
We replace flat roofs in three systems. Two-ply SBS modified bitumen with cap sheet, hand-torched and feathered on every seam. TPO single-ply membrane in 60-mil, 80-mil, and 90-mil thicknesses, hot-air-welded at every overlap. Torch-down replacements of legacy pitch-and-gravel decks where the building owner wants modern weatherproofing without the asphalt and stone weight load. Most Austin flat-roof replacements we run fall in the $10,000 to $35,000 range for residential additions and small commercial sections.
Every flat-roof replacement starts with a deck inspection and core sample where the condition is unclear. We document drainage with a slope reading, photograph every penetration, and write the scope before any tear-off begins. Manufacturer warranty registered in your name before our truck leaves the property.
Two-ply SBS modified bitumen
Base sheet and cap sheet, hot-mopped or hand-torched to project conditions. Feathered seams at every overlap so the bond holds and water cannot wick under the membrane. Twenty-year manufacturer warranty registered in your name.
TPO and EPDM single-ply membrane
60, 80, and 90-mil thicknesses available. Hot-air-welded seams at every overlap. Mechanically attached or fully adhered to building spec. Walk pads at every RTU and access point. 20 to 30 year manufacturer warranty depending on membrane spec.
Torch-down replacement of pitch-and-gravel
Legacy pitch-and-gravel deck stripped to substrate. New base and cap sheet torch-applied and feathered by hand. Eliminates the gravel weight load and the maintenance overhead of the legacy system.
Drainage, scuppers, and pitch pans
Drains rebuilt with new clamping rings. Scuppers replaced where the membrane has failed. Pitch pans poured with two-part urethane sealant. The detail work that decides whether the roof leaks in year three or year twenty.
Manufacturer warranty registration
Two-ply modified bitumen runs 20 years on materials. TPO runs 20 to 30 years. Our written workmanship warranty runs five years on labor, transferable once to the next owner. Both registered in your name before close-out.
How the flat roof replacement process works
Step 01
Deck inspection + core sample
We meet you on the roof, walk every elevation, take a core sample where the deck condition is unclear, photograph every penetration. Free across the Austin metro.
Step 02
System selection + budget
Modified bitumen, TPO, or torch-down replacement. We price the options separately so you can choose what fits the building, the budget, and the long-term plan.
Step 03
Permit and material delivery
City of Austin or whichever municipality applies. Material delivered the day before the crew arrives. Dumpster placement coordinated with the property.
Step 04
Tear-off, feather, and install
Old membrane stripped, deck inspected and replaced where it has failed. New base sheet laid, cap sheet torch-applied and feathered by hand. Drainage and flashings rebuilt at every penetration.
Step 05
Magnetic sweep + warranty registration
Final magnetic sweep across the lawn and beds. Manufacturer warranty registered in your name. Five-year written workmanship warranty on labor.
Frequently asked questions
How much does flat roof replacement cost in Austin?
Modified bitumen runs $8 to $14 per square foot installed in the Austin metro. TPO single-ply membrane runs $11 to $18 per square foot depending on thickness and attachment method. Torch-down replacement of legacy pitch-and-gravel runs $9 to $15 per square foot. Most Austin residential flat-roof replacements fall in the $10,000 to $35,000 range.
What is the difference between torch-down and modified bitumen?
Modified bitumen is the membrane material itself. Torch-down is the installation method. Two-ply SBS modified bitumen can be installed by hot-mopping or by torch-application. Torch-down means the underside of the cap sheet is heated with an open flame and pressed into the base sheet, bonding the two layers as the asphalt melts. Done right, the seam is hand-feathered: hot enough to bond, not hot enough to leak through.
What is pitch and gravel and how do you replace it?
Pitch and gravel (also called built-up roofing or BUR) is the legacy commercial flat-roof system. Layers of asphalt-saturated felt are mopped down hot, then a layer of gravel is embedded into the final mop. Most Austin pitch-and-gravel roofs were installed in the 1960s to 1990s. We replace them with torch-down modified bitumen, which eliminates the gravel weight load and modernises the weatherproofing without changing the roof's structural assembly.
Can you replace a flat roof on a residential addition?
Yes. Residential flat-roof additions are the most common flat-roof replacement we run in Austin. Hill Country modern builds with flat sections, rear-of-house flat additions on 1960s ranches, and porch and patio covers all fall in our wheelhouse. The same family-built crew handles both the residential flat-roof work and the standard pitched-roof work, so the seam where they meet is built right.
How long does a flat roof last in Austin?
Modified bitumen runs 20 to 25 years in the Central Texas climate when installed correctly. TPO runs 20 to 30 years depending on thickness. Torch-down replacements over a sound deck run 20 years on materials. The actual service life depends more on drainage, flashing detail, and how the seams were sealed than on the membrane material itself.
Do you handle flat-roof commercial work?
Yes. About half of our commercial roofing work is flat-roof or low-slope. Modified bitumen, TPO, EPDM, and R-panel metal across warehouses, retail strips, and small office and medical buildings. See our commercial roofing page for the property-manager and ownership-group workflow.