Flat roofs do not fail in the middle.
They fail at the edge metal, at the drains, at the parapet, and wherever somebody set something down on them without flashing it. That is true of a porch roof on a Ridgewood colonial and of a waterfront condominium roof in Edgewater, and it is where a low-slope specification is worth paying for. EPDM, TPO and modified bitumen, detailed properly at the junctions.
Two completely different jobs that share a material.
Bergen County has both, and they are not priced, scheduled or detailed the same way.
The small area on a pitched house
A rear extension, a porch, a bay, a dormer top, a garage. Often under a few hundred square feet.
- Almost all the work is in the junctions, not the field
- A wall abutment with step flashing and a kick-out at the bottom
- A tie-in to the pitched roof above that has to shed, not just seal
- Edge metal on three sides and a gutter on the fourth
- Usually done as part of a re-roof, occasionally on its own
The whole roof of a building
Mid-century houses, and the condominium and apartment stock along the Hudson waterfront.
- Falls, drains and scuppers decide whether it works at all
- Parapet caps and terminations are where wind uplift starts
- Everything set down on it — condensers, aerials, rails — is a penetration
- Phased replacement is often the right answer over occupied units
- A board or managing agent needs a written report, not a verbal
Specified by the roof, not by the truck.
| System | What it is | Where it is the right answer |
|---|---|---|
| EPDM | A single sheet of black synthetic rubber, fully adhered or mechanically fastened, seams bonded | The usual answer on a residential extension, porch or garage. Forgiving of an irregular shape, long-serving, and simple to repair years later |
| TPO | A white or gray thermoplastic sheet, seams hot-air welded rather than glued | Larger exposed roofs over occupied rooms, where a reflective surface keeps the space under it cooler and the welded seam is worth having |
| Modified bitumen | Reinforced asphalt in layers, torch-applied or cold-applied | Small, complicated areas with a lot of detail around them, and roofs where the existing build-up suits staying in the same family of material |
The rolled mineral-surfaced felt still sold for porch roofs has a service life measured in a handful of winters and cannot be detailed properly at a wall. If a quote for a flat area is dramatically cheaper than the others, check which of these four it is actually for.
Six details, and the field of the roof is not one of them.
Edge metal and terminations
Wind gets under an edge before it gets anywhere else. Properly formed drip and gravel stop, mechanically fastened, with the membrane turned and terminated above the water line — not dressed over and sealed.
Drains, scuppers and overflows
A blocked drain turns a roof into a tank. Clamping rings that actually clamp, sumps set below the field, and an overflow that works when the primary is blocked, because one day it will be.
Parapet caps and copings
Water gets into a parapet from the top and comes out inside the building. Caps need falls, joints need covers, and the membrane needs to run up the inside face and terminate properly.
Wall abutments and kick-outs
Where a low-slope area meets a wall, the membrane runs up behind the cladding, not against it. The kick-out at the bottom end is the piece most often missing, and without it water runs down inside the wall.
Everything set down on it
Condensers, aerials, satellite dishes, solar rails, guard rails. Each one is a hole in a watertight surface and each one needs a proper curb or pad. A great many of the leaks we find on flat roofs were installed by another trade.
Falls and ponding
Water still standing two days after rain means the falls, the drains or the deck. Tapered insulation can correct falls without rebuilding the structure, and it is far cheaper than the repeated repairs ponding eventually causes.
What a building needs that a house does not.
Most of the low-slope roof area in Bergen County sits on the Hudson waterfront, on buildings owned by a lot of people at once. That changes the paperwork more than it changes the roofing.
- A written condition report with photographs, before any discussion of cost, so the board is deciding from evidence rather than from a sales visit.
- A scope split into now and scheduled — what is causing damage today, what is worth doing in the same visit while access is set up, and what can be budgeted for a later year.
- Insurance certificates naming the association, and a schedule that says which elevations are affected and when.
- Phasing over occupied units, because a building cannot be opened across its whole roof the way a house can.
- One point of contact who answers the phone, which is the part managing agents actually complain about.
Edgewater carries more of this stock than anywhere else in the county — see flat roofs in Edgewater, where the survey and the repair-or-recover decision are set out in full.
What counts as a low-slope roof?
Anything too shallow for shingle to be rated on — in practice a rear extension, a porch or bay roof, a dormer top, a garage, or the whole roof of a mid-century or waterfront building. The pitch is the thing that decides the material, not the size. Laying shingle flatter than it is rated for is one of the more common causes of a leak we get called to that was built in rather than worn in.
EPDM, TPO or modified bitumen — which is right?
EPDM is the black rubber sheet most people picture: forgiving, long-serving, and the usual answer on a residential extension or porch. TPO is a white or gray welded sheet that reflects heat, which matters on a large exposed roof over occupied rooms. Modified bitumen is a torch- or cold-applied asphalt system that suits small, complicated areas with a lot of detail around them. We specify by the roof, not by what is on the truck.
How long does a flat roof last?
A properly detailed single-ply roof is a decades-long roof, not the five-year patch job flat roofs have a reputation for. That reputation comes from the failure mode: flat roofs almost never fail in the field. They fail at the edge metal, at the drains, at the parapet cap, and wherever somebody set a condenser or an aerial down without flashing it. Those details are where the specification and the money should go.
Why does my flat roof hold water after rain?
Some residual water is normal and drains or evaporates within a day or two. Water still standing after that is ponding, and it means the falls are wrong, the drains or scuppers are blocked, or the deck has deflected. Ponding does not by itself make a hole, but it loads the structure, accelerates the membrane and turns any small defect into a leak. It is worth diagnosing rather than living with.
Can you work on a condominium or apartment building roof?
Yes, and the paperwork side of it matters as much as the roof. A board or managing agent needs a written condition report with photographs, a scope that separates what must be done now from what can be scheduled, and insurance certificates naming the association. We do that as standard; it is the same report a homeowner gets, sized for a building.
Do you work on porch and bay roofs on an otherwise pitched house?
Yes — porch and bay roofs are the most common low-slope roofs in Bergen County. A porch or bay roof is a small area with a great deal of detail around it: a wall abutment, a kick-out, edge metal, and a tie-in to the pitched roof above. Almost all of the work is in those junctions, which is why it is worth doing in a proper membrane rather than in rolled asphalt and sealant.
Where to go next.
Standing seam metal
The other answer on a shallow pitch, and the better one on a visible slope.
Details →Roof inspection
A photographed, written condition report — for a house or for a board.
Details →Urgent leak
Water coming in now. What to do before anyone arrives.
Details →Gutters & drainage
Where the water goes once the roof has shed it.
Details →Find out what the details are doing.
We photograph the edge metal, the drains, the parapet and every penetration, and write a scope that separates the roof from everything other trades have put on it.