Flat roofs don't fail like shingle roofs. Water sits, seams open, and the drip shows up three rooms away. Collins Roofing and Repair repairs and replaces TPO, modified bitumen and coated low-slope roofs on homes, porches, additions and commercial buildings.
We find where the water gets in, fix where it sits, and recommend a repair when a repair will do. Free roof inspections with photos, written estimates and a written workmanship warranty on every job.
A flat roof system is one continuous waterproof layer, not overlapping shingles, laid over a low-slope deck so water can't back up through the laps. Collins Roofing and Repair works with single-ply membranes, modified bitumen and coating systems for homes and commercial buildings.
| System | What It Is | How Seams Close | Typical Lifespan | Approx. Installed Cost (2026) | Best For |
|---|---|---|---|---|---|
| TPO | White single-ply thermoplastic sheet | Hot-air welded into one sheet | 20 to 30 years | $4-$14+ per sq ft | Larger flat roofs, commercial buildings, roofs in full sun |
| Modified bitumen | Polymer-modified asphalt sheets, often a base sheet plus a granulated cap | Torch, cold adhesive or self-adhered laps | About 20 years | $4-$8+ per sq ft | Porches, additions, garages, roofs with foot traffic |
| Rubber membrane (EPDM) | Flexible single-ply synthetic rubber | Taped or adhered | Up to 30 years | $4-$13+ per sq ft | Simple roof shapes, roofs with some movement |
| Silicone roof coating | Liquid-applied coating over a sound existing roof | No seams once cured | 15 to 20 years with maintenance, recoatable | $2-$4+ per sq ft | Aging but dry low-slope roofs, roofs that hold some water |
| Acrylic roof coating | Water-based reflective coating | No seams once cured | 10 to 15 years, recoatable | Lower than silicone | Well-draining roofs in full sun |
TPO is a white single-ply membrane. Its seams are welded with hot air, so the finished roof acts like one sheet with no glue joints to dry out. The bright surface reflects heat, which helps on big flat sections that bake all summer.
Collins Roofing and Repair installs TPO on additions, flat sections and commercial roofs where a reflective, welded system makes sense.
Modified bitumen is asphalt roofing upgraded with polymers so it flexes and handles heat better than old tar and gravel roofs. Most residential systems go down as a base sheet plus a granulated cap sheet, which gives you two layers of waterproofing.
SBS is rubber-modified and stretches more, which helps a roof ride through hot days and cool nights. APP is plastic-modified, resists UV and heat well, and is usually installed by torch.
Torch-down gives a strong bond but uses an open flame. Cold adhesive skips the flame. Self-adhered sheets go down fast but need warm weather and a clean, dry deck. Collins Roofing and Repair explains which method fits your roof and your house.
EPDM is a single-ply rubber sheet that flexes as the building moves. It's dark unless coated, so it runs hotter than TPO in full sun, but it's a proven option on simple roof shapes.
A roof coating is a liquid-applied layer rolled or sprayed over an existing low-slope roof that is still dry underneath. It seals small cracks and seams, reflects sun, and can add years before a tear-off.
A coating sticks to the roof it's applied over. If the insulation is wet, the deck is soft or the membrane is pulling apart, a coating just hides the problem. Collins Roofing and Repair checks for those conditions first and tells you if the roof needs a membrane instead.
"Honest, helpful, and professional about my roof diagnosis. No high pressure sales tactic I’ve experienced in the past"
Low-slope porches and additions leak because shingles shed water by gravity and need pitch to do it. On a roof with too little slope, wind-driven rain pushes back up under the laps. Collins Roofing and Repair fixes this on back porches, sunrooms and shed additions by putting the right material on the right slope.
Roof pitch is written as inches of rise per 12 inches of run. A 2:12 roof rises 2 inches every foot. The International Residential Code, which South Carolina has adopted, sets the floor for each material:
| Roofing Material | Minimum Slope | What That Means on Your Porch |
|---|---|---|
| Asphalt shingles | 2:12, with two layers of underlayment from 2:12 up to 4:12 | Below 2:12, shingles are not allowed |
| Metal shingles | 3:12 | Moderate pitches only |
| Standing seam metal | 1/4:12 | A clean option for shallow porch roofs |
| Modified bitumen | 1/4:12 (1/4 inch per foot) | Built for nearly flat roofs |
| TPO and other single-ply membranes | 1/4:12 | Built for nearly flat roofs |
| Liquid-applied roofing and coatings | 1/4:12 | Over a sound, properly sloped roof |
If your porch sits low but not flat, a standing seam metal roof can be a cleaner-looking alternative to membrane.
Ponding water is water still sitting on a roof 48 hours after the rain stops in drying weather. That's the common industry line between normal runoff and a drainage problem. Ponding speeds up membrane wear and adds weight the deck wasn't built to carry.
Fixing ponding means changing the shape of the roof, not just the surface. Common fixes include replacing soft decking, adding tapered insulation to build in slope, adding a cricket to split water around a curb, and adding or enlarging a drain or scupper.
"He took pictures of what needed to be done and discussed it with me. I approved what needed to be done and agreed on the price."
Flat roof repair makes sense when the damage is limited to one area and the fix costs a small slice of a new roof. Replacement makes sense when water has spread under the membrane or ponding covers large sections. Collins Roofing and Repair shows you photos of both before you decide.
| Repair Usually Makes Sense When | A Coating Can Make Sense When | Replacement Usually Makes Sense When |
|---|---|---|
| The leak traces to one seam, blister or flashing | The membrane is aging but still dry and attached | Leaks keep coming back in different spots |
| Insulation and decking are dry | Small cracks and seams are spread across the roof | Water has soaked insulation or rotted decking |
| Ponding is minor and the drain is fixable | You want to add years before a tear-off | Ponding sits 48 hours or more across several areas |
| The rest of the roof has life left | The roof is sound but reflects heat poorly | The membrane is shrinking, splitting or pulling loose |
"Good value. Good workmanship. Good communications. Good cleanup."
Most homes with a flat section also have a pitched roof that needs attention. Collins Roofing and Repair handles every part of it with one team.
Every roof we inspect, repair and replace.
Leaks, flashing, vents and skylights traced to the source.
Full tear-off and new roof for the pitched part of your home.
Standing seam panels for shallow porches and whole-house roofs.
Membranes, coatings and metal for offices, shops and warehouses.
Emergency tarping when a storm opens up a flat roof.
Free inspections with photos of every issue.
Patching the same flat roof every summer gets old. Book a free inspection with Collins Roofing and Repair. We'll find where the water gets in, fix where it sits, and show you the before and after photos before we call it done.
