Metal roofing
Architectural shingles
Tile roofing
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Flat & low-slopeFree roof inspection with deck photos before we talk money - GAF and Owens Corning certified installation
Fast, Reliable Roof Installation Across San Marcos
A new roof in San Marcos, TX typically costs between $8,500 and $16,500 for a standard composition shingle installation on a 1,500 to 2,200 square foot home, and most full replacements take two to five days once materials are on site. Those are real numbers, not estimates pulled from a national average. We know this market because we work in it weekly, from the pier-and-beam bungalows near the historic downtown to the new subdivisions spreading west toward the Hill Country. Grant Whitlock leads our team, and he’ll be the first to tell you that the price you’re quoted is the price you pay, in writing, before a single nail goes down. Call (361) 202-8874 and a live person answers, any hour, any day.
Leading Roof Installation Across San Marcos
San Marcos gives roofs a beating. Hays County sits in Flash Flood Alley, where spring storms drop five to ten inches of rain in a matter of hours, hail the size of golf balls hammers shingles, and wind gusts ahead of a storm hit 60 mph before the sky even darkens. We’re not a company that looks at a San Marcos roof and says the same thing we’d say in Dallas. We look at your slope, your valley lines, your decking condition, and the specific way water moves across your roofline during a Hill Country downpour. That local reading is why Roof Installation done by our crew holds up when the next storm rolls through.
You’ll also know exactly who’s walking up your driveway. Every Mercer Roofing technician is background-checked, identity-verified, and dispatched under the Threshold Verified standard. Before your appointment, we send you the technician’s name and photo. At your door, they present a photo ID badge and arrive in a clean, marked uniform. If you’re home alone, if you have young children, if you’re an older homeowner who’s been burned by a door-to-door roofer before, that badge matters. Grant Whitlock has built this company on the belief that you shouldn’t have to wonder who’s on your property. And when you call (361) 202-8874, you get a person, not a voicemail tree.
Styles & brands we work with
Roof Flashing Installation in San Marcos
Roof flashing installation in San Marcos is one of the highest-ROI parts of a new roof, because Flash Flood Alley rains exploit weak flashing faster than anything else. Flashing is the metal, usually galvanized steel or aluminum, that seals the joints where your roof meets a chimney, wall, skylight, or valley. When flashing is thin, poorly lapped, or sealed with cheap caulk instead of proper fasteners, water finds it. On 1970s and 80s ranch-style homes with low-slope roofs around San Marcos, we routinely find valley flashing that was never installed to code, which is exactly where the leaks start during those intense spring cloudbursts.
A proper flashing installation in San Marcos runs $500 to $1,800 for a typical home, depending on how many valleys, chimneys, and penetrations your roof has. That price includes removing old flashing, cutting and lapping new metal, and sealing with a quality polyurethane sealant, not acrylic caulk. The cheap bids skip the step flashing on dormer walls or use roll roofing instead of actual metal in the valleys. Those shortcuts fail within two to three years here.
Valley and Penetration Flashing
Valleys carry more water than any other part of your San Marcos roof, especially on low-slope ranch designs. We use minimum 26-gauge metal, lapped correctly against the direction water flows, then sealed at the lap joints. Penetrations, meaning plumbing vents, attic fans, and furnace stacks, get individual flashing boots with proper sealant around the pipe collar.
Chimney and Sidewall Flashing
Chimney flashing is the most frequently botched detail in San Marcos roof replacements, particularly on older homes near Texas State University. Step flashing must be woven into each course of shingles, with a counter-flashing cut into the mortar joint. Skipping the counter-flashing saves an hour of labor and guarantees a leak inside three years.
TPO Roofing Installation in San Marcos
TPO roofing installation in San Marcos uses thermoplastic polyolefin membrane, a single-ply white roofing system that’s become the standard for low-slope commercial and residential roofs across Hays County. The white surface reflects heat, which matters a lot in a city with six months of 90-plus degree days. On the low-slope 1970s and 80s ranch homes scattered across San Marcos, a properly installed TPO roof can cut attic temperatures by 20 to 30 degrees compared to a dark modified bitumen roof. It also handles ponding water better than most alternatives, which is critical when Flash Flood Alley drops five inches of rain in an afternoon.
A TPO installation on a San Marcos home typically runs $6.50 to $9.00 per square foot installed, so a 1,500 square foot low-slope roof would land between $9,750 and $13,500. That includes tear-off of the old roof, new insulation board, mechanically attached or fully adhered membrane, and all edge metal and flashing details. Fully adhered TPO costs more but stands up better to the high wind uplift that Hill Country storms generate. The most common failure we see is not the membrane itself but the seams, which were welded too quickly or by an installer without proper TPO training.
Heat-Welded Seams
TPO seams are welded with hot air, not glued, and the weld has to be done at the right temperature and speed or the seam separates under wind load. Our crews test-weld every morning and check every seam with a probe after welding. That’s the difference between a TPO roof that lasts 20 years and one that blows apart in the first big storm.
Insulation and Drainage Planning
TPO goes down over rigid insulation board, and on San Marcos low-slope roofs, we plan the taper to move water toward drains and scuppers rather than letting it pond. Ponding water on a San Marcos roof in July turns the surface into a hot bath that degrades materials much faster than the manufacturer’s warranty assumes.
Trusted Brands We Service in San Marcos
We install and repair GAF, Owens Corning, IKO, and Atlas roofing systems in San Marcos, and we keep local stock of the most common matching accessories, ridge caps, and flashing components so we’re not waiting on a distributor when your project is underway. For homeowners who want impact resistance for hail season, Atlas StormMaster and Owens Corning Duration FLEX carry Class 4 impact ratings, which matters when spring storms roll through Hays County. If you have a specific brand preference, tell us when you call and we’ll spec the quote around that product line. Grant Whitlock’s position is simple: use a manufacturer-recognized system, installed to the manufacturer’s nailing pattern, with the warranty registered in your name. No off-brand generics, no mystery shingles from a warehouse closeout.
See the difference
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AfterCommon Roof Installation Problems We See in San Marcos Homes
- Cedar shake over spaced decking on pre-1950 bungalows. Homes east of Texas State University and near the historic downtown often have original cedar shake or three-tab shingles nailed to spaced board decking. Current code requires solid decking for proper nailing patterns, so full redecking is usually mandatory on a replacement.
- Granule loss and shingle blow-off along eaves. Hill Country wind gusts ahead of hailstorms routinely exceed 60 mph, and older three-tab installations without a starter strip fail first at the eaves and rakes. Starter strip is code now, but many San Marcos homes predate that requirement.
- Valley and penetration leaks on low-slope ranch homes. The 1970s-80s ranch-style houses across San Marcos were built when roof slopes flatter than 4:12 were considered fine without ice and water shield. They’re not. Wind-driven rain forces water under the shingles and into valleys and around vents, rotting decking that’s invisible until tear-off.
- Improper ventilation trapping Hill Country humidity. Hot, humid San Marcos summers and a poorly vented attic create condensation on the underside of the roof deck, which rots plywood from above your ceiling. A proper installation includes calculating ridge and soffit venting for your square footage, not just reusing whatever was there.
Pricing for Roof Installation in San Marcos, TX
A full composition shingle roof replacement in San Marcos typically runs $8,500 to $14,000 for a standard single-story home up to 2,000 square feet. Larger or two-story homes run $12,000 to $18,000. TPO on a low-slope roof runs $9,750 to $13,500 for 1,500 square feet. Roof flashing installation runs $500 to $1,800 depending on the number of valleys and penetrations. What moves the price is decking condition, roof pitch, number of stories, and the shingle class you choose, Class 4 impact-rated shingles add $800 to $1,500 but may reduce your insurance premium in Hays County’s hail zone. Every Mercer Roofing quote is written, itemized, and fixed. No change orders, no surprise line items on invoice day. Call (361) 202-8874 to schedule your free estimate.
We Also Serve Cities Near San Marcos
Our crews cover San Marcos and the surrounding Hays County area, with regular work in Austin, Bastrop, Cedar Park, and Hutto. If you’re in one of those cities and need Roof Installation in San Marcos standards applied to your home, we’ll bring the same wind-load documentation and permit handling we use here. Same written pricing, same badge-at-the-door policy, same 365-Day Done Right Promise.
Serving San Marcos, TX - Our Local Coverage Area
We’re based in the San Marcos area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About Roof Installation in San Marcos
Yes. The City of San Marcos requires a building permit for any roof replacement, and the process includes a pre-installation inspection, a decking inspection after tear-off but before underlayment and shingles go on, and a final inspection after the roof is complete. A compliant San Marcos installer pulls the permit, schedules each inspection, and documents the entire sequence for your records. The decking inspection is the one that matters most for older homes near Texas State University, because that’s when the inspector verifies that the nailing pattern and decking meet the 115 mph wind standard required by the 2018 IRC for Risk Category II structures. Cheap bids skip the permit entirely or tell you it’s your responsibility, which it is not. Call (361) 202-8874 for an estimate that includes all permit and inspection coordination.
Hays County enforces the 2018 International Residential Code, which requires roof decks to be designed for a minimum wind speed of 115 mph for Risk Category II homes, and your shingle system must be installed to the manufacturer’s high-wind nailing pattern, not the standard six-nail pattern. Owens Corning Duration and Atlas StormMaster systems can achieve 130 mph wind warranties when installed with the high-wind pattern and a starter strip. The nailing pattern is the part that cheap installers skip because it uses more fasteners and takes longer. We document the pattern on every San Marcos installation so you have proof for your insurance file.
Documented wind and hail compliance gives you leverage with your insurance carrier in two ways. First, having a written record of the nailing pattern, underlayment type, and shingle wind rating makes a post-storm claim faster and harder to deny, because the adjuster can’t argue the roof was improperly installed from the start. Second, Class 4 impact-rated shingles like Atlas StormMaster or Owens Corning Duration FLEX often qualify for a premium discount with Texas carriers, since hail is the primary claims driver in Hays County. We give every San Marcos customer a compliance package with photos, nailing pattern documentation, and product specs. Ask for it when you call (361) 202-8874 for your free estimate.
Yes, in almost every case. Spaced board decking from the early 20th century cannot meet the nailing density required by the 2018 IRC for 115 mph wind zones, and you cannot install architectural shingles over cedar shake because the surface is too uneven for proper sealing. Full redecking means removing the old shake and spaced boards, installing new plywood or OSB decking to code thickness, and then building your new roof system on a solid, nailable surface. On a 1920s bungalow near the historic downtown, our crew did exactly this, we stripped original cedar shake that had hail splits from a spring storm, installed new plywood decking, synthetic underlayment with ice and water shield in the valleys, and a GAF architectural system with a 130 mph wind rating. We then documented the nailing pattern for the homeowner’s insurance file. Expect redecking to add $2,500 to $5,000 to a full replacement depending on roof size. Call (361) 202-8874 for an exact quote.
A compliant quote includes the City of San Marcos permit with all three inspection fees, full redecking where the existing decking is spaced or rotted, a starter strip on every eave and rake, ice and water shield in valleys and at eaves, synthetic underlayment, and the manufacturer’s high-wind nailing pattern documented in writing. The cheap bid leaves out the permit, skips the starter strip, uses 15-pound felt instead of synthetic, omits ice and water shield entirely, and nails six fasteners per shingle instead of the high-wind pattern. That bid saves $1,500 to $3,000 upfront and costs a full replacement after the next major hailstorm. We’ll show you both columns, honestly, and let you decide. Call (361) 202-8874 to schedule a free estimate and get a written, itemized quote.
Your roof is the only thing between your family and a Flash Flood Alley hailstorm. Get a written price, know who’s at your door, and know the work will be done to the wind rating San Marcos actually requires. Call (361) 202-8874 and ask for Grant Whitlock. Free estimates, written warranties, and a live person every time.
Written by Grant Whitlock, Owner at Mercer Roofing Co Austin, serving San Marcos and surrounding Hays County communities.