Flat roofs that drain instead of pond
Shingles need slope to shed water. Below that, a roof needs a membrane: one continuous sheet with welded or glued seams and a clear path to the drain.
Charlotte has more flat and low-slope roofs than people expect: mid-century modern homes in neighborhoods like Cotswold and Sedgefield, screened porches and sunrooms tied into a main roof, garage and kitchen additions, rowhouse-style townhomes in South End, and small commercial buildings all over the county. They fail differently from pitched roofs. Water sits on them, so the weak points are seams, flashing where the roof meets a wall, and anywhere water ponds for days after a storm.
For most replacements we recommend TPO, a white single-ply membrane whose seams are welded with hot air into one continuous sheet. The white surface reflects summer sun, which helps the rooms underneath. EPDM, the black rubber membrane, is still a good choice in some spots and is easy to repair. For both, the job starts by removing the old roof, fixing the deck, and installing insulation; where water ponds, we add tapered insulation or crickets to steer it toward drains and scuppers.
Repairs on flat roofs are common and often worth doing: a split seam, a punctured membrane under a satellite dish, or a scupper that has pulled away from the wall. We clean and prepare the surface, weld or adhere a patch of matching membrane, and check the rest of the seams while we're up there. If more than a few areas are failing, or the insulation underneath is soaked, replacement usually costs less over time than chasing leaks.
Low-slope roofs in a residential replacement in Mecklenburg County fall under the same permit rule as any re-roof, and we handle the application.
What the job includes
TPO membrane
White, heat-welded single-ply membrane with seams fused into one sheet.
EPDM option
Black rubber membrane where it suits the building or matches existing roofing.
Drainage fixed
Tapered insulation and crickets to move water off flat spots and toward drains.
Wall and curb flashing
Membrane turned up walls, curbs and parapets and terminated properly.
Repairs
Seam welds, punctures and scuppers repaired with matching membrane.
Tie-ins
Clean transitions where a flat porch roof meets a shingled main roof.
What flat and low-slope roofs costs in Charlotte
| Work | Typical range | What changes it |
|---|---|---|
| TPO roof, porch or small addition | $3,500 – $9,000 | Size, insulation, wall flashing |
| TPO roof, flat-roof house | $9 – $15 per sq ft | Tapered insulation, drains, parapets |
| EPDM roof replacement | $8 – $13 per sq ft | Fully adhered or ballasted |
| Seam or puncture repair | $300 – $900 | Size and membrane type |
| Add a drain or scupper | $700 – $2,000 | Location and structure |
| Tapered insulation to cure ponding | $4 – $8 per sq ft added | Depth of slope needed |
Ranges are planning numbers for the Charlotte area in 2026, not quotes. Your price comes in writing after the inspection, with materials named and the permit listed when one is required.
On the job
Flat and low-slope roofs: common questions
Is some ponding normal on a flat roof?
A little water that's gone within a day or two after rain is common. Water that sits longer stresses the membrane and finds every weak seam. Tapered insulation fixes it.
TPO or EPDM: which is better?
Both work when installed well. TPO's welded seams and white surface make it our usual pick for Charlotte summers; EPDM is a solid choice for some repairs and certain buildings.
Can you just coat my old flat roof?
Coatings can extend a roof that's dry underneath. If the insulation is wet or seams are failing, a coating traps the problem. We check before recommending one.
How long does a flat roof last?
A well-installed membrane roof commonly lasts a couple of decades or more, depending on the product, the drainage and how often people walk on it.
Can you fix the leak where my porch roof meets the house?
That joint is one of the most common leak spots. It usually needs the membrane run up the wall under the siding or flashing, not more sealant on top.
Do flat roofs need a permit?
A replacement does in Mecklenburg County, the same as a pitched roof. Small repairs usually don't.