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Flat Roof Installation Pflugerville TX
Flat roof installation Pflugerville TX property owners ask about comes down to one idea: a flat roof is never actually flat. It is a drainage design built in layers, and most flat roofs that fail were drained badly long before they were waterproofed badly.
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Tell us what the roof covers — a whole building, an addition, a carport or a porch — roughly how big it is, and whether there is an old roof on it now. That last answer changes the whole job.
No obligation. Serving Pflugerville, Austin and the surrounding Central Texas area.
The short version
Water has to be off the roof within 48 hours, which means at least a quarter inch of fall per foot and a planned path to a drain, gutter or scupper. Under the membrane sit insulation and a cover board; the membrane is fastened, glued or weighted down. And whether an old flat roof can be recovered instead of torn off is decided by finding out if it is wet — which is a scan, not a guess.
Every flat roof is a drainage plan
A steep roof sheds water whether anyone planned it or not. A low-slope roof only drains if someone designed it to, and that design is most of what separates a flat roof that lasts from one that leaks.
The 48-hour test
Some water sitting on a flat roof after a storm is normal. The common industry test for a problem is water still standing 48 hours after the rain stops. Past that point it is called ponding, and ponding is where membranes age fastest, seams get stressed, and a small defect becomes a leak.
A quarter inch per foot, minimum
Building codes generally require at least a quarter inch of fall per foot for the common single-ply and modified bitumen membranes. That sounds small. Over a 40-foot run it is ten inches, and getting it consistent across a whole roof is real work.
Where the slope actually comes from
Three ways, often combined. The framing itself can be built with fall. Tapered insulation — boards cut thicker at one end — can create slope on a dead-level deck. And crickets, small raised wedges, push water around curbs, units and between drains so it does not collect behind them.
Where the water goes
Off the edge into a gutter, through a scupper in a parapet wall, or down an internal drain. Each one needs sizing for a Central Texas downpour, and each one is a hole in the waterproofing that has to be flashed. A flat roof quote that does not say where the water leaves is missing the most important line.
What sits under the membrane
The membrane is the part everyone talks about and the thinnest layer in the system. What is beneath it decides how it performs.
| Layer | What it is | Why it matters |
|---|---|---|
| Deck | Wood sheathing on homes and small buildings; steel or concrete on larger ones | Everything is fastened to it. Soft or wet decking has to be replaced before anything goes on top |
| Insulation | Usually rigid foam boards, flat or tapered | Carries the slope when the deck is level, and slows heat moving into the building in summer |
| Cover board | A thin, dense board over the insulation | Gives the membrane a hard surface, resists foot traffic and hail, and protects the softer foam below |
| Membrane | TPO, EPDM or modified bitumen, among others | The waterproofing. Thickness and seam method matter as much as the material name |
| Edge metal and flashing | Drip edge, gravel stop, wall and curb flashings | Where the membrane ends or turns up a wall — and where most low-slope leaks begin |
The Pflugerville heat question
On a roof over conditioned space, a white, reflective membrane runs far cooler on the surface than a dark one through a Central Texas summer, which reduces the heat moving down into the building. That is the main reason white TPO has become the default on so many low-slope roofs here. Over an open carport or an unconditioned porch the energy argument largely disappears, and other factors decide the choice.
Material by material, the trade-offs are on our roofing materials guide.
Three ways a membrane is attached
Wind does not push a flat roof down; it pulls it up. How the membrane is attached is how it resists that, and it is worth knowing which method you are being quoted.
| Method | How it works | Suits | Ask about |
|---|---|---|---|
| Mechanically fastened | Plates and screws through the membrane edge into the deck, covered by the next sheet’s seam | Many commercial roofs; quick and economical | Fastener spacing at the corners and perimeter, where uplift is highest |
| Fully adhered | The membrane is glued across its whole surface to the board beneath | Homes, smaller roofs, and anywhere a smooth, quiet finish matters | Which adhesive, and whether the weather allows it to cure properly on the day |
| Ballasted | Loose membrane held down by stone or pavers | Some large commercial roofs; rarely right on a house | Whether the structure can carry the weight |
Recover it or tear it off
Putting a new membrane over an existing flat roof saves the tear-off. It is also the single most common way a new flat roof is ruined before it starts.
What the codes generally allow
Building codes generally permit one recover over an existing roof, and only when the old roof and its insulation are dry and sound. Not over two existing layers, and not over anything water-soaked or deteriorated. Your local permitting office is the authority on the specifics for your building.
Why wet insulation is the whole question
Seal a new membrane over wet insulation and the water has nowhere to go. It stays in the roof, it keeps the deck damp, and the new roof starts failing from underneath while looking perfect from above.
How we find out
An infrared scan shows where wet insulation is holding heat differently from dry material, across the whole roof rather than one spot. Suspect areas are then confirmed physically with a small test cut. The result is a map: dry enough to recover, wet in patches that can be cut out and replaced, or wet enough that tear-off is the only honest answer.
Two quotes worth walking away from
A recover with no moisture check. If nobody has scanned or cut the existing roof, nobody knows whether it is wet, and the quote is a bet placed with your money.
A flat roof quote with no drainage line. If the scope names the membrane but not the slope, the crickets or where the water leaves, it is pricing the waterproofing and skipping the design. A coating rolled over a roof that already ponds belongs in the same category — it changes the colour of the puddle, not where the water goes.
What a flat roof scope should name
Two flat roof quotes can differ by a wide margin and both be honest, because they describe different roofs. These lines tell you which roof each one is pricing.
| Line | What to look for |
|---|---|
| Membrane and thickness | The product and its thickness, not just “TPO”. Single-ply membranes are sold in several thicknesses, and thicker sheets cost more and last longer |
| Attachment | Fastened, adhered or ballasted, and the fastening pattern at corners and edges |
| Insulation | Type, thickness, whether it is tapered, and whether a cover board is included |
| Drainage | Where the slope comes from, any crickets, and every drain, scupper or gutter by location |
| Existing roof | Tear-off or recover — and if recover, how dryness was confirmed |
| Edges and flashing | Edge metal, and how high the membrane turns up walls and curbs |
| Warranty | Manufacturer and installer coverage stated separately, with the certificate terms rather than a summary |
What separates the two kinds of warranty is on our warranty information page, and every term above is defined in plain English in the roofing glossary.
Homes and whole buildings
On a house, a flat roof is usually one section rather than the whole thing — an addition, a porch, a carport, or a low-slope area where two roof planes meet. Those are still installed with the same discipline: real slope, a drainage path, and a proper turn-up where the low roof meets the wall or the shingles. If the whole house is being re-roofed at the same time, our roof installation Pflugerville TX page covers the steep-slope side.
On a commercial building, the flat roof is the roof, and drainage, attachment and recover decisions are made across the entire surface. That work is covered on commercial roofing Pflugerville TX.
Already leaking? The entry point on a flat roof is rarely above the stain inside — our roof leak guide explains why, and if water is coming in now, start with emergency roof repair Pflugerville TX.
Flat roof questions, answered
How much slope does a flat roof need?
Building codes generally require a minimum of a quarter inch of fall per foot for the common single-ply and modified bitumen membranes. That slope can come from the framing, from tapered insulation, or from crickets that steer water toward a drain, gutter or scupper.
What counts as ponding on a flat roof?
The common industry test is water still standing 48 hours after the rain stops. Water that clears within a day or two is normal on a low-slope roof; water that is still there after two days means the drainage design is not working.
Can a new flat roof go over my old one?
Sometimes. Building codes generally allow one recover over an existing roof only when the old roof and its insulation are dry and sound, and not over two existing layers. Whether yours is dry is answered with a moisture scan and test cuts, not by looking at the surface.
Is a white membrane worth it in Pflugerville heat?
On a roof over conditioned space, usually. A reflective white membrane runs much cooler on the surface than a dark one in a Central Texas summer, which reduces heat moving into the building. Over an unconditioned porch or carport the energy benefit matters less.
How long does a flat roof last in Central Texas?
It depends on the membrane, its thickness, how it was attached and above all how well the roof drains. Service lives are set by the manufacturer for the specific product and should be read on its documentation; a well-drained, well-detailed roof reaches the top of that range and a ponding roof does not.
Do you install flat roofs on homes or only commercial buildings?
Both. On homes that usually means additions, porches, carports and low-slope sections that meet the main roof; on commercial buildings it means the whole roof.
Where to go next
Pflugerville roofing guides and hubs
Find out what your flat roof actually needs
We walk the roof, check where water sits and where it leaves, scan the existing roof for trapped moisture, and put it in writing — drainage, layers, attachment, and whether the old roof can stay. The report is yours to keep, or to hand to another contractor for a competing quote.
We are a local company doing roofing in Pflugerville, Austin and the surrounding Central Texas area. Every service we offer is on Pflugerville roofing services. Coverage detail is on our roofing service area page.
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Pflugerville Roofing Pros · Pflugerville, TX · pflugervilleroofingcompany.com
Serving Pflugerville, Austin and surrounding Central Texas. ESTIMATES: any figure discussed is for budgeting rather than quotation; a firm price requires someone on site, because roof size, slope, drainage, existing layers, deck condition, insulation and membrane all move it. CODES: slope, recover and flashing requirements referenced here are general; the adopted code and the local permitting authority govern your specific building. Product service lives, thicknesses and wind ratings are manufacturer specifications for the specific product and should be read on its documentation. Infrared and thermal imaging indicate temperature differences consistent with trapped moisture; they are a diagnostic aid rather than a certainty, and findings are confirmed physically. Warranty terms are set by the manufacturer and installer, vary by product and system, and should be read on the certificate itself. HOA covenants and any applicable permitting are the property owner’s responsibility to confirm. Texas does not issue a statewide roofing contractor license; verify any roofer on insurance certificates sent directly by the insurer and on manufacturer certification for the specific product quoted. General information about construction practice, not legal or engineering advice.