Flat Roofing Near You for TPO, Modified Bitumen and Membrane Roofs on Porches, Additions and Commercial Buildings
Charleston Roofs and Windows Repairs and Replaces Low-Slope and Specialty Roofs That Shingles Can't Handle
Flat roofs don't fail like shingle roofs. Water sits. Seams open. The drip shows up three rooms away. Charleston Roofs and Windows repairs and replaces modified bitumen, TPO and membrane roofs on homes and commercial buildings.
Got a porch, addition or dormer with barely any pitch? That's where shingles leak and membranes win. Free inspection, written estimate, 0% financing for 12 months.
- 4.9 Stars, 680 Google Reviews
- BBB A+ Accredited
- 0% Financing for 12 Months
- Atlas Pro+ Diamond Level
- Viwinco Blue Label
How to Choose a Flat Roofing Company Near You That Fixes the Water, Not Just the Leak
Choosing a flat roofing company near you means finding one that asks where the water goes, not just where it drips. Charleston Roofs and Windows has seen it firsthand: a low section installed wrong by someone else, leaking into the house.
"Apparently a flatter portion of our roof was improperly installed (by a different company) causing a leak into the house and rotten plywood under the shingles. These folks came out, inspected, and repaired that section."
Three Questions to Ask a Flat Roofer Before You Sign
These three questions separate a real low-slope contractor from a shingle crew with a roll of membrane.
Which Membrane Do You Recommend, and Why for My Roof?
Modified bitumen, TPO and rubber membrane each fit different roofs. A porch with foot traffic and a 3,000 square foot commercial roof shouldn't get the same answer by default.
How Charleston Roofs and Windows Answers
Charleston Roofs and Windows installs modified bitumen, TPO and membrane systems, and your inspection manager explains why one fits your roof better than the others before you pick.
● Free Inspections and Written Estimates
Every flat roof visit from Charleston Roofs and Windows is free, and the price comes in writing.
What Will You Do About the Water That Ponds Up There?
New membrane over a low spot just gives the water a fresh surface to sit on. Ask how the roofer plans to move water to a drain, scupper or gutter.
How Charleston Roofs and Windows Answers
Charleston Roofs and Windows looks at where the water exits, not just where it drips, and puts any drainage work in the written estimate. That way the new roof doesn't hold water like the old one.
Will You Repair It if a Repair Is Enough?
A lot of flat roof leaks start at one failed seam or flashing. Some contractors only quote full replacement.
How Charleston Roofs and Windows Answers
If a repair solves it, that's what Charleston Roofs and Windows quotes. When the roof is past saving, we show you the photos that prove it.
● W2 Project Managers and a Final Walkaround
A W2 project manager oversees the crew and walks the finished roof with you, the same as on every Charleston Roofs and Windows job.
Red Flags on a Flat Roof Bid
Nobody can price a flat roof from the driveway.
for a roof with soaked insulation or soft decking.
That's a leak on a schedule.
on a roof that holds water for days.
Flat Roof Systems Compared : Modified Bitumen, TPO and Rubber Membrane
A flat roof system is a continuous waterproof membrane, rather than overlapping shingles, laid over a low-slope deck so water can't work its way back up through the laps. Charleston Roofs and Windows installs three main systems for Lowcountry homes and commercial buildings.
- What It Is Asphalt sheets reinforced with polymers, usually two plies with a granulated cap
- How Seams Close Torch, cold adhesive or self-adhered laps
- Typical Lifespan 15 to 20 years on the SC coast, up to 25 for premium systems
- Approx. Installed Cost (SC, 2026) $5 to $8 per sq ft
- Best For Porches, garages, dormers and roofs with foot traffic
- What It Is White single-ply thermoplastic sheet
- How Seams Close Hot-air welded
- Typical Lifespan 20 to 30 years
- Approx. Installed Cost (SC, 2026) $7 to $12 per sq ft
- Best For Larger flat roofs, commercial buildings, sun-baked roofs
- What It Is Flexible single-ply synthetic rubber
- How Seams Close Taped or adhered
- Typical Lifespan 20 to 30 years
- Approx. Installed Cost (SC, 2026) $4 to $8 per sq ft
- Best For Roofs with movement, simple shapes
Modified Bitumen: The Workhorse for Porches and Additions
Modified bitumen is an asphalt roofing membrane upgraded with polymers so it flexes and resists 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 vs. APP Modified Bitumen
SBS is rubber-modified and stretches far more, which helps a roof ride through heat swings. APP is plastic-modified with stronger UV and heat resistance, and it's installed almost exclusively by torch.
Torch, Cold-Applied or Self-Adhered
Torch-down gives the strongest bond but uses an open flame. Cold adhesive skips the flame. Self-adhered sheets go down fastest but need warm weather and a clean deck. Charleston Roofs and Windows explains which method fits your roof and your house.
TPO: Reflective and Built for Sun
TPO is a white single-ply membrane whose seams are welded with hot air into one continuous sheet. The bright surface reflects heat, which is why it's a common pick for commercial roofs and big flat sections under full sun. Charleston Roofs and Windows installs TPO on homes and businesses.
Rubber Membrane Roofs
Rubber membrane is a single-ply sheet that flexes with the building as it moves. It handles expansion and contraction well and avoids the hot-asphalt smell some homeowners notice from bitumen roofs on summer afternoons.
Waterproofing for Decks, Walls and Problem Spots
Waterproofing is the layer that keeps water out where a roof meets a wall, a deck or a parapet. In a wet, humid climate, it's what stops mold and mildew from starting inside the framing. Charleston Roofs and Windows adds it where the roof calls for it.
"We had a leak in a flat roof over a part of our house. Michael came out in June 2025 and looked both at that leak and (at my request) the rest of the roof. He walked me through what he saw and what he recommended... Better yet, it's been over 6 months, and no leak at all."
Flat Roofs on Commercial Buildings
Offices, shops, warehouses and multi-tenant buildings usually sit under TPO or modified bitumen. Charleston Roofs and Windows repairs and replaces commercial flat roofs, from a leaking shop roof to a full tear-off.
"We had some storm damage to the roof of our shop and he was able to come look at, quote and repair the same day! Couldn't be more pleased with the job he did."
Why Low-Slope Porches, Additions and Dormers Leak (And What Belongs on Them)
Low-slope porches, additions and dormers leak because shingles shed water by gravity and need pitch to do it, so a roof with too little slope lets wind-driven rain push back up under the laps. Charleston Roofs and Windows fixes it on back porches, sunrooms and shed dormers.
Minimum Roof Slope by Material
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 sets the floor for each material:
What That Means on Your Porch Below 2:12, shingles are not allowed
What That Means on Your Porch A steep-roof material only
What That Means on Your Porch Not for shallow porches
What That Means on Your Porch Moderate pitches
What That Means on Your Porch A strong option for shallow porch roofs
What That Means on Your Porch Built for nearly flat roofs
If your porch sits low but not flat, a standing seam panel roof can be a cleaner-looking alternative to membrane.
Ponding Water: When Standing Water Becomes a Problem
Ponding water is water still sitting on a roof 48 hours after the rain stops in drying weather. That's the industry line between normal runoff and a drainage problem. Ponding speeds up membrane breakdown and adds weight the deck wasn't built to carry.
What Causes Ponding
- Sagging or rotted decking that forms a bowl under the membrane.
- Too little slope from the original build, under the 1/4 inch per foot minimum.
- Clogged drains, scuppers and gutters packed with oak leaves and pine straw.
- Crushed insulation from foot traffic or old equipment.
How It Gets Fixed
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, installing a cricket to split water around a curb, and adding or enlarging a drain or scupper.
"...did a great job putting on a new roof, costing our low slope roof area and replacing our damaged roof decking areas. Cleaned up and worked a 12 hour day."
How to Reach Charleston Roofs and Windows and Where to Find Us
Charleston Roofs and Windows gets an inspection manager onto your flat roof fast, usually within a day or two, and can tarp an active leak while the repair is scheduled.
Call Us
Talk to the Charleston Roofs and Windows office team at 843-955-8558. If water is coming in under a flat section right now, tell them so an emergency tarp can be arranged.
843-955-8558 →Book Online
Fill out the free inspection form with your name, phone and address, and note that the leak is on a flat or low-slope section. Our office team calls you back to confirm a time.
Visit Our Office
Charleston Roofs and Windows 9565 William Aiken Ave Ste 102Ladson, SC 29456
843-955-8558 Get Directions ↗
What Happens After You Reach Out
We call you back to confirm a time that works.
An inspection manager visits and photographs the membrane, seams, flashing and drains.
You get a written estimate with the repair or replacement and any drainage fix spelled out.
You decide. No pressure, no expiring "today only" pricing.