San Antonio Flat Roof Repair, Replacement, and Installation
Flat and low-slope roofs protect thousands of commercial buildings, apartments, and homes across San Antonio. They require specialized materials, installation techniques, and maintenance approaches that are completely different from pitched roofing. Not every roofing company has the expertise, and hiring the wrong contractor is the number one reason flat roofs fail early.
Legacy Home Improvements has been installing and repairing flat roofs across San Antonio for over 25 years. We work on everything from small residential patio covers to 100,000+ square foot commercial buildings. As a Premier Contractor, we bring factory-trained crews, proper heat-welding equipment, and honest assessments to every flat roof project.
Whether you need emergency leak repair, a full commercial re-roof, or a cost-effective coating to extend your current roof by a decade, we start with a free inspection and give you real options with transparent pricing. No pressure, no upselling, just the facts about your roof.
Flat Roofing Systems We Install and Repair
TPO (Thermoplastic Polyolefin) is the most popular flat roof system in San Antonio for good reason. The white reflective membrane bounces solar heat instead of absorbing it, reducing cooling costs by up to 30 percent in our brutal summers. TPO sheets are heat-welded at every seam, creating a continuous waterproof barrier with no adhesive to fail. Cost: $5.50 to $8.50 per square foot installed. Expected lifespan: 20 to 30 years. TPO is Energy Star certified and qualifies for local utility rebates in some cases.
Modified Bitumen is a rubber-based rolled roofing system with outstanding flexibility. It handles the extreme temperature swings San Antonio is known for, from occasional freezes to 110+ degree summer days, without cracking or splitting. Modified bitumen comes in torch-applied, cold-adhesive, and self-adhered options. Cost: $5 to $8 per square foot. Expected lifespan: 15 to 25 years. This is a strong choice for residential flat sections and smaller commercial buildings.
PVC (Polyvinyl Chloride) is the premium single-ply option. PVC membranes have superior chemical resistance, making them the go-to choice for restaurants, commercial kitchens, and buildings near grease exhaust. PVC is also heat-welded and highly resistant to fire, wind, and puncture. Cost: $7 to $12 per square foot. Expected lifespan: 25 to 35 years.
Built-Up Roofing (BUR) uses multiple alternating layers of asphalt and reinforcing fabric, topped with a gravel surface coat or mineral cap sheet. BUR systems have been protecting commercial buildings for over a century. The multi-layer construction provides maximum redundancy: even if one layer is compromised, the others continue to protect. Cost: $6 to $10 per square foot. Expected lifespan: 25 to 40 years. BUR is the most puncture-resistant flat roof system available.
Liquid-Applied Coatings (silicone or acrylic) are applied directly over an existing flat roof to extend its life by 10 to 15 years without a full tear-off. This is the most cost-effective option when the existing roof structure is sound but the membrane is aging. No tear-off means no landfill waste, less disruption, and lower cost: typically $3 to $6 per square foot. We take core samples during inspection to verify that the existing system can support a coating.
Flat Roof Cost Guide for San Antonio (2026)
Flat roof pricing depends on the system, building size, accessibility, number of penetrations (HVAC units, vents, drains), and whether tear-off of the existing roof is required. Here is what San Antonio property owners typically pay in 2026:
For a 2,000 square foot commercial flat roof: TPO replacement runs $11,000 to $17,000. Modified bitumen runs $10,000 to $16,000. PVC runs $14,000 to $24,000. BUR runs $12,000 to $20,000. A liquid coating over existing roof runs $6,000 to $12,000. Tear-off and disposal of the old roof adds $1 to $2 per square foot if a second layer cannot be applied over the first.
For residential flat sections (porches, additions, garages), the typical project is 200 to 800 square feet. Smaller scale means slightly higher per-square-foot pricing, but total project cost is usually $2,500 to $8,000 depending on the system and scope.
We provide free, detailed written estimates that break down material costs, labor, tear-off, and disposal separately. Every estimate includes a scope of work document so you know exactly what is included. No hidden fees, no surprise charges.
Common Flat Roof Problems in San Antonio
Ponding water is the number one flat roof problem in San Antonio. Water that sits on the roof more than 48 hours after rain accelerates membrane deterioration, adds dangerous structural weight, breeds mosquitoes, and eventually finds its way inside. Ponding is caused by clogged drains, insufficient slope, structural settling, or HVAC equipment blocking drainage paths. The fix is improving drainage through tapered insulation, additional drains, or clearing blocked scuppers. The cost of fixing ponding is always less than the water damage it causes.
Membrane blistering and cracking happens when San Antonio UV exposure and extreme heat cause trapped moisture between roof layers to expand. Small blisters can be monitored. Large, soft blisters should be repaired before they crack open and become active leak points. The root cause is almost always moisture in the roof system from a past leak, poor installation, or inadequate ventilation.
Seam separation at flashings and penetrations is the second most common leak source. Every pipe, HVAC curb, drain, and wall transition is a potential failure point. Seams fail when adhesive breaks down in UV exposure, when thermal movement stresses joints, or when the original installation was done with sealant instead of proper mechanical attachment.
Hail damage to flat roof membranes is often invisible from the ground. Unlike shingle roofs where hail damage shows as obvious dents and missing granules, flat roof hail damage can be subtle: small punctures in TPO, fractures in modified bitumen, or displaced gravel in BUR systems. After any significant hail event in San Antonio, have a professional inspect your flat roof even if you do not see obvious damage.
Thermal expansion and contraction from San Antonio temperature swings (daily temperature change of 30+ degrees is common) causes fastener back-out, membrane stretching, and stress cracks at fixed connection points. Proper installation accounts for this movement. Improper installation creates dozens of future failure points.
Flat Roof Maintenance Schedule
Flat roofs require more regular attention than pitched roofs. A consistent maintenance schedule prevents small issues from becoming expensive emergencies. Here is what we recommend for San Antonio flat roofs:
Every quarter: Clear all drains, scuppers, and gutters of leaves, dirt, and debris. San Antonio live oak leaves, pecan husks, and dust accumulate quickly and block drainage paths. Blocked drains are the number one cause of ponding.
Twice per year (spring and fall): Walk the roof and inspect for blisters, cracks, seam separation, flashing deterioration, and signs of ponding. Check all penetration seals around HVAC equipment, vents, and pipes. Document any changes with photos.
After every significant storm: Inspect for hail damage, wind-lifted membrane, displaced gravel, and debris impacts. San Antonio averages 2 to 4 significant hail events per year, and each one can cause damage that goes unnoticed until the next heavy rain.
Every 5 years: Schedule a professional inspection that includes core samples if the roof is over 10 years old. Core samples reveal trapped moisture, insulation deterioration, and deck condition that cannot be seen from the surface.
Every 10 to 15 years: Plan for re-coating on coated systems and SPF roofs. A timely re-coat extends roof life significantly and costs a fraction of replacement.
Why Flat Roof Experience Matters
Flat roofing is a completely different trade from residential shingle roofing. The materials, tools, installation methods, and failure points have almost nothing in common. A company that primarily installs asphalt shingles may not own a hot-air welder for TPO seams, may not understand torch safety for modified bitumen, and may not know how to properly calculate drainage slope.
We have seen flat roofs fail in under 5 years because a shingle crew used adhesive instead of heat-welded seams, or used residential-grade flashing at wall transitions, or left the roof without adequate slope to drain. These are not cosmetic issues. They are fundamental installation errors that guarantee premature failure.
Legacy has dedicated flat roof crews who work on commercial and residential flat roofs year-round. Our crews are factory-trained on TPO, PVC, and modified bitumen systems. We own the specialized equipment required for proper flat roof installation. We understand drainage requirements, membrane compatibility, building code specifics, and the unique demands that San Antonio weather puts on flat roof systems.
Flat Roof Repair vs. Replacement: How to Decide
Not every flat roof problem requires a full replacement, and we will never recommend one when repair will solve the issue. Here is how we help you decide:
Repair makes sense when: the damage is isolated to one area, the rest of the membrane is in good condition, ponding is caused by a blocked drain rather than structural slope issues, or the roof is less than 15 years old with no widespread deterioration. Typical flat roof repairs in San Antonio cost $500 to $3,000 depending on scope.
Coating makes sense when: the existing membrane and deck are structurally sound but aging, there are no active leaks or trapped moisture, and you want to extend roof life by 10 to 15 years at 40 to 60 percent of the cost of full replacement.
Replacement makes sense when: there are multiple active leaks, the membrane shows widespread cracking or alligatoring, core samples reveal saturated insulation, the roof is 20+ years old with chronic issues, or previous repairs keep failing because the underlying system is compromised.
We provide honest assessments. If a $800 repair solves your problem, that is what we recommend. Our reputation depends on doing the right thing, not the most expensive thing.
Properties We Serve
- Office buildings, medical offices, and professional complexes
- Retail centers, strip malls, and standalone storefronts
- Restaurants, bars, and commercial kitchens (PVC recommended for grease resistance)
- Warehouses, distribution centers, and industrial buildings
- Multi-family apartment complexes and condominiums
- Residential flat sections: porches, additions, garages, and modern home designs
- Churches, schools, and municipal buildings
- HOA common areas and clubhouses
San Antonio Flat Roof Service Areas
We provide flat roof repair, replacement, and maintenance across the entire greater San Antonio metro area. Our service territory includes San Antonio, Alamo Heights, Terrell Hills, Olmos Park, Castle Hills, Shavano Park, Leon Valley, Balcones Heights, Helotes, Boerne, Fair Oaks Ranch, Bulverde, Spring Branch, New Braunfels, Schertz, Cibolo, Garden Ridge, Seguin, Converse, Live Oak, Universal City, Kirby, Windcrest, and all surrounding communities in Bexar, Comal, Guadalupe, Kendall, Medina, and Wilson counties.
Need a flat roof inspection, repair, or replacement in San Antonio? Call Legacy Home Improvements at (210) 272-7272 for a free, no-obligation estimate. We have been protecting San Antonio flat roofs for over 25 years and we would welcome the opportunity to protect yours.
Frequently Asked Questions
What is the best material for a flat roof in San Antonio?
TPO is the most popular choice for commercial flat roofs in San Antonio because the white reflective membrane cuts cooling costs in our extreme heat. For residential flat sections, modified bitumen offers excellent durability against temperature cycling from below freezing to 110+ degrees. PVC is the premium option with superior chemical resistance, making it ideal for restaurants and commercial kitchens. We assess your building during a free inspection and recommend the best system for your situation.
Do flat roofs leak more than sloped roofs?
Not when installed correctly with proper slope-to-drain. Every flat roof should have at least 1/4 inch per foot of slope for water to reach drains, scuppers, or gutters. Leaks happen when drainage is insufficient, seams fail, or flashing pulls away from walls. We use heat-welded seams (not adhesive) that create a monolithic waterproof barrier, and we ensure proper drainage on every project.
How long does a flat roof last in San Antonio?
Lifespan depends on the system: TPO lasts 20 to 30 years, modified bitumen 15 to 25 years, PVC 25 to 35 years, and built-up roofing (BUR) 25 to 40 years. Spray foam coatings add 10 to 15 years when applied over an existing system. These numbers assume proper installation and regular maintenance. San Antonio UV exposure and hail are the two biggest lifespan reducers, both of which proper material selection helps mitigate.
How much does a flat roof cost in San Antonio?
Flat roof costs in San Antonio range from $4 to $12 per square foot depending on the system: TPO runs $5.50 to $8.50/sq ft, modified bitumen $5 to $8/sq ft, PVC $7 to $12/sq ft, and BUR $6 to $10/sq ft. Liquid coatings over an existing roof cost $3 to $6/sq ft. A 2,000 sq ft commercial flat roof replacement typically runs $11,000 to $17,000. We provide free, detailed estimates with transparent per-square-foot pricing so you can compare options clearly.
Can you coat an existing flat roof instead of replacing it?
In many cases, yes. If the existing membrane and decking are structurally sound, a silicone or acrylic coating can add 10 to 15 years of life without a full tear-off. This typically costs 40 to 60 percent less than a complete replacement. We take core samples during inspection to verify the existing roof layers can support a coating. If there is trapped moisture or deck deterioration, coating will not solve the problem and we will tell you that upfront.
How do I know if my flat roof needs repair or replacement?
Signs you need repair: isolated ponding, small blisters, minor seam separation at one or two spots, or a single leak point. Signs you need replacement: widespread cracking or alligatoring, multiple active leaks, saturated insulation (we can verify with core samples), membrane that tears easily when pulled, or a roof that is 20+ years old with chronic issues. We provide honest assessments and will never recommend replacement when repair will solve the problem.
Do you repair flat roofs on commercial buildings?
Yes. We handle flat roof repair, maintenance, coatings, and full replacement for commercial properties of all sizes across San Antonio, from 1,000 sq ft retail shops to 100,000+ sq ft warehouses. We schedule work around your business hours and stage materials in advance so there is minimal disruption to your operations or your customers.
What causes ponding water on a flat roof?
Ponding happens when water remains on the roof more than 48 hours after rain. Common causes include clogged drains or scuppers, insufficient original slope, structural settling over time, HVAC equipment blocking drainage paths, and sagging deck from past moisture damage. Solutions range from clearing drains and adding crickets to installing tapered insulation for proper slope. Ponding should always be addressed because standing water accelerates membrane deterioration and adds structural weight.
Is a flat roof good for solar panels?
Flat roofs are actually ideal for solar panels. The flat surface allows panels to be mounted at the optimal tilt angle for San Antonio latitude (about 29 degrees) for maximum energy production. Flat roofs also make solar installation faster and less expensive because workers can move safely without fall protection concerns. If you are considering solar, have the roof inspected first to make sure it does not need repair or replacement before panels go on top.
Do you offer flat roof maintenance plans?
Yes. Our flat roof maintenance program includes quarterly drain and scupper clearing, bi-annual membrane inspections for blisters, cracks, and seam issues, post-storm damage assessments after significant weather events, and annual detailed reports with photos. Preventive maintenance typically costs a fraction of emergency repairs and extends roof life by years.
What areas do you serve for flat roof work?
We serve the entire greater San Antonio area including Boerne, New Braunfels, Schertz, Seguin, Converse, Live Oak, Universal City, Cibolo, Garden Ridge, Helotes, Leon Valley, Alamo Heights, Terrell Hills, Olmos Park, and surrounding communities in Bexar, Comal, Guadalupe, Kendall, and Medina counties.