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COMMERCIAL ROOF REPLACEMENT

Black Metal & TPO Commercial Roof Replacement in South Congress, Austin TX

An aging, heavily patched asphalt roof was replaced with black metal and TPO, and tear-off revealed $4,500 in necessary decking repairs.

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Standing water pooling on the exposed low-slope deck, the drainage problem that led to TPO membrane on this South Congress roof.

Project Overview

Driftwood Builders Roofing completed a commercial roof replacement near South Congress in Austin, Texas. The existing sloped roof used aged asphalt shingles with extensive granule loss, exposed asphalt, roof cement, and repeated patching. The low-slope section also showed standing water and an older roof surface that required replacement.


The original $18,000 scope included tear-off, new roofing materials, complex installation work, a black metal roofing system on the sloped areas, and TPO on the flat section. Once the old roof was removed, the crew discovered widespread rotted and open decking. Correcting those concealed conditions added $4,500, bringing the final project investment to $22,500.


The finished roof combines clean black metal panels with a dedicated TPO system for the low-slope area. The project also included integration of rooftop penetrations and ventilation, cleanup, and final quality-control review.

Project Details

Black Metal & TPO Commercial Roof Replacement in South Congress

Detail Info
Roof type Mixed-slope commercial roof
Sloped sections Black exposed-fastener metal roofing
Low-slope/flat section TPO membrane roofing
Issue found before repair Heavily patched asphalt, standing water on low-slope area
Issue found during tear-off Rotted/open decking
Original scope $18,000
Hidden decking repair +$4,500
Final project total $22,500

Why This Austin Commercial Roof Needed Two Different Roofing Systems

Most commercial buildings in Austin aren’t a single roof. They’re two or three roof types stitched together: a sloped section over the occupied space, a low-slope or flat section over an addition or mechanical area, sometimes a third pitch over an entry. Each of those planes sheds water at a different rate, and that single fact determines what can go on them.

The dividing line is roof pitch. Above roughly 3:12, water leaves the surface fast enough that a panel system with overlapping seams will stay dry. Below that, water slows down, sits, and finds every seam and fastener penetration it can. On this South Congress building, the sloped sections cleared that threshold and the low-slope section did not. The during-photos show standing water pooling on the exposed deck, which is precisely the condition that had rotted the decking underneath and added $4,500 to the job.

Yes, and on mixed-slope commercial buildings it’s usually the correct approach rather than a compromise. Metal goes on the sloped sections where pitch sheds water; TPO membrane goes on the low-slope or flat sections where water sits. The two systems join at a transition flashing detail. The key is that the transition is designed as part of the job, not improvised at the end. Water must move from the metal onto the membrane surface without crossing a seam or fastener. On this South Congress project, black exposed-fastener metal covered the sloped planes and a fully-adhered TPO membrane covered the low-slope portion.
single-ply membrane (TPO, PVC, or EPDM) or a modified bitumen system. TPO is the most common choice in Austin because it’s white or light-colored, which reflects heat and reduces cooling load through Texas summers, and because its seams are heat-welded rather than glued, producing a continuous watertight surface. Low-slope roofs can’t rely on gravity to move water off quickly, so the roof itself has to be watertight rather than water-shedding. Asphalt shingles and exposed-fastener metal both fail this test and should not be used below about a 3:12 pitch.
Not exposed-fastener metal, no. Exposed-fastener panels are attached with screws driven through the panel face, each sealed with a rubber washer. On a pitched roof that’s fine: water never sits long enough to matter. On a flat or low-slope roof, standing water sits directly on those penetrations, the washers degrade, and the roof leaks at every screw. Standing-seam metal with hidden clips performs better and some systems are rated down to a 1/4:12 pitch, but it costs significantly more than a membrane and offers no real advantage on a flat surface. For a genuinely flat roof, a membrane system is both the cheaper and the better-performing answer.

They’re not competitors; they solve different problems. Metal is the better choice on sloped, visible roof planes: 40 to 70 year lifespan, strong wind and impact resistance, and it’s the surface people actually see. TPO is the better choice on low-slope and flat planes: a continuous heat-welded membrane with no fastener penetrations through the field, reflective for heat management, and typically 20 to 30 years. A building with both slope types should generally have both materials. Asking which is “better” overall is like asking whether a wall or a floor is better construction. The right answer depends on which plane you’re covering.

A matched system: the right material on each plane, with an engineered transition where they meet. In practice for Austin that usually means metal or architectural shingles on the sloped sections and a TPO or PVC membrane on the low-slope sections. Three things determine whether it holds up: the pitch threshold is respected on every plane, the transition detail is designed rather than patched, and the decking is inspected and replaced during tear-off rather than covered over. That last point is where budgets move: on this project, rotted decking discovered after tear-off added $4,500 to a $18,000 starting estimate.
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So the building got two systems. Black exposed-fastener metal on the sloped planes, where the pitch does the work and the panels shed cleanly. A fully-adhered TPO membrane on the low-slope section, where there is no pitch to rely on and the roof has to be genuinely watertight rather than water-shedding. The two systems meet at a transition detail with flashing designed to carry water off the metal and onto the membrane without a seam in the path.

Putting metal across the whole building would have been faster to quote and cheaper on paper. It would also have put a screw-penetrated panel system under standing water, the same failure the owner was already paying to fix.

What Is the Black Tar on an Older Austin Roof?

ROOF CEMENT AND REPEATED PATCHING

WHY WAS SO MUCH BLACK ROOF CEMENT VISIBLE?

Black roofing tar is commonly roof cement used around penetrations, seams, flashings, and temporary repairs. It can be useful when applied correctly for a suitable detail, but widespread surface application often indicates repeated attempts to manage deterioration or water entry. It is not a permanent substitute for sound decking, correct flashing, and a roof system suited to each slope.

Rotted decking exposed around a turbine vent opening during tear-off on the South Congress commercial roof in Austin, TX.

ROOF REPLACEMENT COST

Why the Roof Was Replaced

The before-condition photos show an asphalt roof near the end of its practical service life, with widespread granule loss, exposed asphalt, aging accessories, and extensive roof-cement repairs. These visible conditions supported full replacement rather than another isolated patch. Tear-off was also necessary to evaluate the roof deck and create a reliable foundation for the new systems.

Scope of Work: Metal and TPO Roof Replacement

The completed roof replacement scope included the following work:

Why Rotted Decking Added $4,500

Decking is the structural surface beneath the visible roofing. Existing shingles and underlayment can conceal moisture-related deterioration, open holes, and weakened wood. On this project, those problems became clear only after tear-off. Installing a new metal or membrane roof over unsound decking would have compromised fastening, transitions, and long-term performance, so the damaged areas had to be corrected first.

The decking work was a documented hidden-condition change of $4,500. That addition increased the original $18,000 roof scope to a final project investment of $22,500.

Crew member on the completed black exposed-fastener metal roof overlooking the South Congress street in Austin, TX 78704.

Can a Roofer Know How Much Decking Is Rotten Before Tear-Off?

Not always. Roof shingles, membranes, underlayment, and other roofing materials can conceal the condition of the roof deck, so some rotted or deteriorated decking may not become visible until the existing roofing system is removed during tear-off.

On this Austin commercial roofing project, the original contract was $18,000. Once the existing roof was removed, concealed rotted and open decking was discovered and required $4,500 in additional decking repairs. The final project investment was $22,500.

This is why an accurate roof replacement estimate can change after tear-off. A contractor can inspect visible areas before construction begins, but hidden decking damage may only be confirmed once the existing roofing materials are removed.

Standing water pooling on the exposed low-slope deck, the drainage problem that led to TPO membrane on this South Congress roof.
Completed black exposed-fastener metal roof with two circular vents on a commercial property near South Congress in Austin, TX 78704.

Why Was TPO Used on the Low-Slope Roof Instead of Metal?

This South Congress property contained both sloped and low-slope roof sections. Rather than forcing one roofing system across areas with different drainage conditions, the replacement was designed around each roof geometry.

Black metal roofing was installed on the sloped roof sections, while TPO membrane roofing was used on the low-slope portion where water drainage and waterproofing requirements differ.

Before Photos

The original commercial roof showed extensive age-related deterioration and repeated attempts to manage problem areas with roof cement and patches.

During Photos: Rotted Decking Discovered

Tear-off exposed widespread deterioration, holes, and unsuitable decking. The low-slope area also showed standing water that reinforced the need for a properly detailed replacement system.

After Photos

The completed sloped roof uses clean black exposed-fastener metal panels with integrated turbine vents. A dedicated TPO system was installed on the low-slope section.

How Much Did This South Congress Commercial Roof Cost?

The original proposal totaled $18,000. Rotted decking discovered during tear-off added $4,500, bringing the final project investment to $22,500.
Project Scope Investment Amount
Tear-off and disposal $1,200
Metal roofing materials, underlayment, and accessories $10,000
Complex roofing installation labor $3,800
TPO replacement on low-slope section $3,000
Original roof-replacement scope $18,000
Rotted decking repairs discovered during tear-off $4,500
Final project investment $22,500

Important Pricing Disclaimer

This pricing applies only to this commercial property and the documented project scope. Roofing costs vary with measured area, access, slope, structural conditions, panel and membrane specifications, rooftop equipment, drainage, permitting, disposal, labor, and conditions discovered during tear-off. The $4,500 decking addition was specific to concealed deterioration found on this project.

What Our Customers Say

We are large enough to get the job done right, yet small enough to provide old-fashioned customer service. What This South Congress Commercial Customer Said (roof inspection and roof repair, in the $18,000 to $20,000 range).
J Brown
★★★★★
“What a fantastic company! I did a lot of shopping for a roof replacement for our commercial property on South Congress and Driftwood Builders far and beyond was the most affordable and most attentive.”

How Our Roof Replacement Works

1. Free Inspection & Estimate

We inspect the full roof and assess the shingles, decking, flashing, and ventilation, then provide a free, no-obligation estimate.

2. Honest Recommendation

We tell you honestly whether a targeted repair or a full replacement is the right long-term value for your home, with no pressure.

3. Tear-Off & Installation

After tear-off, we inspect the exposed roof deck and address concealed deterioration before installing the roofing systems appropriate for each roof slope. On this project, black metal roofing was installed on the sloped sections and TPO was installed over the low-slope section.

4. Final Check & Cleanup

We verify flashing, ventilation, and workmanship, complete a magnetic nail sweep, and finish with a final quality-control inspection.

Related Austin Roofing Resources

More on the shingle system, decking work, and insurance process behind this Tarrytown project.

Front view of a white two-story house with a stone facade, sloped roof, and glass doors, set against a bright blue sky and a large tree on the left; pool edge in the foreground.

South Austin Roofing

Trusted South Austin roofing contractor serving Zilker, Bouldin, Travis Heights & 78704 since 2005. GAF Master Elite certified, 4.9 stars, free inspections, no deposit required.

Austin Commercial Roofing

Commercial roofing for Austin businesses: metal, TPO, and flat roof systems built to last. Free photo-documented inspections with remaining roof life reported in writing.

Austin Metal Roofing

Standing seam and exposed-fastener metal roofing installed across Austin, lasting 40 to 70 years. Reflects heat, cuts cooling costs, and holds up to Central Texas hail and storms.

View of a brown shingled roof with a vent pipe, overlooking a backyard with trees, a circular fire pit, a stone path, and a wooden fence beyond the lawn.

TPO Roofing in Austin

Heat-welded TPO membrane roofing for flat and low-slope commercial buildings in Austin. UV, chemical, and puncture resistant with a fully sealed, leak-proof seam system.

Flat Roof Repair & Replacement

Flat and low-slope roof repair and replacement for Austin homes and businesses. Free inspection identifies leaks, ponding, and membrane damage before they spread.

A large two-story suburban home with multiple brown garage doors, tan tiled roof, and a light stone-paved driveway, viewed from above. Landscaping lines the front yard.

Commercial Roof Replacement

Full tear-off commercial roof replacements with a complete decking inspection included. No deposit required: you pay only after the finished roof passes inspection.

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Roof Decking Repair

Rotted or damaged roof decking replaced sheet-by-sheet at a rate agreed upfront. Every tear-off includes a full decking inspection before new materials go down.

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Roofing Tips & Education

Frequently Asked Questions

Can metal roofing and TPO be used on the same building?
Yes. Many commercial and mixed-slope buildings use metal on the steeper roof planes and TPO on the low-slope or flat sections of the same structure, since each material performs best within a specific pitch range.
TPO is heat-welded at the seams, creating a fully sealed membrane that doesn’t depend on pitch to shed water the way shingles or metal panels do. It’s also reflective and resists UV, punctures, and chemical exposure, making it well suited to Austin’s heat and low-slope commercial roofs.
Not typically. Metal panels rely on slope to shed water; on a flat plane, seams and fasteners are more prone to water intrusion. Flat or low-slope areas usually call for a membrane system like TPO instead.
Cost depends on roof size, current condition, decking condition, and the mix of metal vs. TPO square footage. Driftwood provides project-specific pricing after a free on-site inspection rather than a general estimate.

The original scope was $18,000. Concealed rotted decking discovered during tear-off added $4,500, bringing the final project investment to $22,500.

What happens if rotted decking is discovered during a commercial roof replacement?
Once the old roofing material is torn off, the exposed decking is inspected. Any sections found rotted, delaminated, or structurally compromised are documented with photos and replaced before new roofing goes down, creating a solid substrate for the new system.
Sometimes there are warning signs (soft or spongy spots underfoot, sagging deck lines, or interior water stains), but decking condition can only be fully confirmed once the existing roofing and underlayment are removed.
It depends on how many sheets need replacing, which isn’t known until tear-off. Driftwood handles this with a per-sheet rate agreed on upfront, so there’s no surprise pricing if rotted sections turn up.
Exposed-fastener panels are attached with screws through the panel face. They are more affordable upfront but need periodic fastener maintenance as seals age. Standing-seam panels attach with hidden clips under raised seams and no exposed fasteners. They have a higher upfront cost, lower long-term maintenance, and a 40-to-70-year lifespan.
It varies with building size, roof complexity, and whether decking repairs are needed, but most combination metal-and-TPO commercial projects run from several days to a couple of weeks from tear-off to final inspection.

Commercial Roofing Services Near South Congress

Driftwood Builders Roofing provides commercial roof inspections, roof replacement, metal roofing, TPO and other low-slope roofing solutions, decking repairs, ventilation, flashing, and storm-damage documentation throughout Austin and Central Texas. Businesses and property owners in South Congress, SoCo, and ZIP code 78704 can request an inspection and detailed proposal based on site-specific measurements and conditions.

Tear-off in progress revealing open holes and unsuitable decking on the South Congress commercial roof in Austin, TX.
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