Flat and Rubber Roofing on Cape Cod
Coast Carpentry Home Improvement installs and repairs flat and low slope roofs on Cape Cod: rubber membrane and modified bitumen for porch roofs, shed dormers, additions, garages and any section too low for shingles. We are a local crew based in Osterville, licensed and insured, and we hold the CertainTeed Silver Star credential for modified bitumen roofing. The work is done by our own people, never subcontracted.
Why a Flat Roof Is a Different Job
Shingles are made to shed water downhill. Below a certain pitch, water stops running and starts sitting. That is a different roof, built a different way.
Water sits instead of running
On a steep roof, gravity does most of the work. On a flat or low slope roof, rain and snowmelt sit until they find a way off, and the way off is often through a seam, an edge, or a nail hole. Everything about a good flat roof is designed around moving that water.
Shingles fail below about 3 in 12
Asphalt shingles are not made for low pitch. Below roughly three inches of rise per foot, wind driven rain and melting snow work back up under the courses. A lot of the leaks we see on Cape homes are shingles on a section that should have had a membrane from the start.
Drainage comes first
Before we choose a material, we look at where the water goes. Where it does not move, we correct the slope with tapered insulation or add a drain or scupper. A membrane laid over a roof that ponds will fail at the seams no matter how well it is installed. Ponding is the problem we are actually solving.
Rubber or Modified Bitumen? What We Install and Why
Two proven systems, two different jobs. We install both, and we will tell you plainly which one fits your roof.
EPDM rubber membrane
A single layer of synthetic rubber, laid in wide sheets with as few seams as possible, fully adhered and sealed at every edge and penetration. It flexes with Cape winters, handles standing snow, and is a strong choice for larger, simpler roofs such as a garage or a full flat addition.
Modified bitumen
Asphalt based rolled roofing, reinforced and applied in layers, with a granulated cap sheet on top. It is tough underfoot, takes detail work well, and suits porch roofs, dormers and complicated sections with a lot of edges, walls and penetrations. This is the system we hold CertainTeed Silver Star certification for.
How we decide
Size and shape of the roof, how many penetrations and walls it meets, whether anyone will walk on it, and how the water leaves. Large and open usually means rubber. Small and busy usually means modified bitumen. Either way, the deck has to be dry and sound before anything goes down.
CertainTeed is North America’s largest roofing manufacturer. Silver Star is their credential for modified bitumen installers, and it means our crew has been trained and vetted against their installation standards for low slope roofing.Where Cape Homes Need a Membrane Roof
Most Cape Cod houses are not flat roofed. Most of them have a flat or low slope section somewhere, and it is usually the part of the roof that leaks.
- Shed dormers. The single most common low slope roof on the Cape. A shed dormer adds a second floor’s worth of headroom, and its roof runs at a pitch far too shallow for shingles.
- Porch and entry roofs. Farmer’s porches, side entries and mudroom roofs are almost always low slope, and they tuck under a wall where water backs up.
- Additions and bump outs. A kitchen bump out, a first floor addition, or the connector between a house and a garage. These are built low to clear the second floor windows above them.
- Garages and outbuildings. Detached garages, sheds and studios with a true flat roof or a very shallow pitch.
- Sections under a deck or a roof deck. Anywhere people will walk needs a membrane that stands up to foot traffic.
We handle the whole roof, so when the low slope section meets the shingled main roof, the transition is flashed by the same crew, not by two contractors pointing at each other.
How a Flat Roof Install Goes
No surprises, no mystery crews. Here is what actually happens once you say yes.
Inspection and a written estimate
We walk the roof after a rain if we can, look for ponding, probe the deck for soft spots, and photograph what we find. You get a clear written estimate, and if a repair will do, we say so.
Tear off and deck
The old roofing comes off. Wet or rotted decking is replaced. We do not seal a new membrane over a wet deck, because trapped moisture is how a flat roof rots from the inside.
Fix the drainage
Tapered insulation, a new drain or scupper, or a corrected edge detail, whatever it takes so water leaves the roof instead of sitting on it.
Membrane and seams
Rubber or modified bitumen goes down with the fewest seams the roof allows. Every seam, edge and penetration is sealed and checked.
Flashing and transitions
Where the flat section meets a wall, a chimney, a skylight or the main shingled roof, we flash it properly. That transition is where most flat roof leaks start.
Cleanup and walkthrough
We protect your property while we work and haul away every scrap. When it is done we walk the roof with you, and we show you where the water goes.
Flat Roof Repair
A flat roof that keeps leaking after repairs almost always has the same cause: the water is still sitting.
Patching a flat roof is easy and it is usually the wrong thing. A roof that ponds will find the next weak seam after you fix the last one, and you end up paying for the same leak three times. When we are called for a flat roof leak, we look at the whole roof first, find where the water stands, and tell you whether a repair actually solves it or only moves it.
Real repairs we do all the time: resealing a failed seam, reflashing a chimney or sidewall, replacing a cracked pipe boot, and adding a drain or scupper where water has nowhere to go. If the membrane is at the end of its life or the deck is wet underneath, we will show you the photos and lay out the real options rather than sell you a patch. If your roof is leaking right now, call (508) 360-9658 and tell us it is active. Leaks move to the front of the line.
Where We Install Flat and Rubber Roofs
Coast Carpentry serves all of Cape Cod, which is every town in Barnstable County, and nowhere else. Our shop is in Osterville, in the town of Barnstable, so we are close to the whole Cape.
That includes the villages homeowners actually say when they call us: Osterville, Centerville, Hyannis, Cotuit, Marstons Mills, West Barnstable, Woods Hole, Dennisport, South Yarmouth and the rest.
Flat Roofing Questions, Answered Straight
What counts as a flat or low slope roof?
Any roof where water does not reliably run off on its own. A true flat roof still has a slight pitch to a drain or an edge. Below roughly three inches of rise per foot, asphalt shingles are the wrong material, because wind driven rain and melting snow work back up under them. That is where a membrane roof belongs.
Rubber or modified bitumen, which is better?
Neither, in general. Rubber suits large, simple, open roofs. Modified bitumen suits roofs with lots of edges, walls and penetrations, and it stands up better to foot traffic. We look at the roof and tell you which one fits, and we install both.
Why does my flat roof keep leaking after repairs?
Almost always because the repair patched a symptom and the water is still sitting. A flat roof that ponds will find the next weak seam after you fix the last one. The fix is drainage, which is where we start, and it is why we look at the whole roof before we quote a patch.
Can you put a rubber roof over the old one?
Sometimes, but we prefer not to, and we will not do it over a wet deck. Trapped moisture under a new membrane is how a roof rots from the inside. We inspect first, and if the deck is dry and sound we will tell you what your options are.
What does CertainTeed Silver Star mean?
CertainTeed is North America’s largest roofing manufacturer, and Silver Star is their credential for modified bitumen installers. It means our crew has been trained and vetted against their installation standards for low slope roofing, and it lets us offer manufacturer warranty options an uncredentialed installer cannot. Ask us about warranty choices during your estimate.
My flat roof is leaking right now. How fast can you come?
Call (508) 360-9658 and tell us it is active. Leaks move to the front of the line, and we will get eyes on it as fast as we can.
Have a Roof Too Flat for Shingles?
Get a straight answer from a crew certified for this work. Free written estimate, no pressure.