Syracuse and the surrounding Onondaga County area
Flat and Low-Slope Roofing
Re-cover a porch, dormer or addition roof too shallow for shingles, with a membrane system and a drainage plan that can carry a season of standing snow.
What Flat Roofs covers
A flat or low-slope roof is a different assembly from the sloped roof above it, and in Onondaga County it does a harder job. It does not shed snow, so it carries the season's load in place, and water that cannot run off freezes and thaws in it repeatedly through the winter. These roofs are everywhere on the older housing here: front porches, rear additions, dormer tops, bay projections and the flat sections of Victorian and early twentieth century houses in the villages and the city. The Village of Liverpool singles them out, requiring a building permit for performing any work on a flat roof, including but not limited to hot tar or rubber membrane. The systems are single ply membrane, modified bitumen and, historically, built-up hot tar, and the decision between them is usually made by the drainage rather than by the material.
- Single ply membrane, EPDM and TPO, on porch, addition and dormer roofs
- Modified bitumen systems, self-adhered and torch applied
- Tear-off of failed built-up roofing and old rolled asphalt
- Deck repair and tapered insulation to move water toward a drain or an edge
- Wall terminations, counterflashing and the transition where a low slope meets the steep roof above it
- Drainage details: scuppers, internal drains, gutter and downspout sizing and discharge
- Repair of seam splits, blisters and ponding related failures on membranes still worth keeping
- Low-slope detailing on shallow porch roofs where asphalt shingles are below the manufacturer's minimum slope
What changes the scope of the work
Every property is different. These are the factors that decide what the job actually involves.
The actual measured pitch
This decides the whole specification. Below the shingle manufacturer's stated minimum slope, asphalt shingles are the wrong product no matter how well they are laid, and above it the roof may not need a membrane at all. Measure before assuming either.
Where the water goes and how long it takes
Water that stands on a low-slope roof here goes through roughly 84 freeze and thaw crossings a year. Ice grows in every seam and lap it can reach, so drainage is the first design decision and the membrane is the second.
Snow load on a plane that cannot shed
A flat roof holds the whole winter in place, and this area normally takes 123.8 inches of snow a year with 92 of those inches between December and February. The ground snow load that governs is the figure your own municipality has entered, increased above 1,000 feet of elevation, which matters if the framing is being touched.
What is already on the deck
Old built-up roofing, rolled asphalt and previous membranes stack up. The code does not permit a recover where two or more applications already exist or where the existing roof is water soaked or too deteriorated to be an adequate base, and a saturated flat roof is very often exactly that.
The transition to the roof above
Snow and meltwater from the main slope dumps onto the low-slope section, and that junction is where most of these roofs fail. It needs a proper termination and flashing, not a bead of sealant where two materials meet.
The municipality
The Village of Liverpool requires a permit for any work on a flat roof by name, including hot tar and rubber membrane. Elsewhere the position varies, and DeWitt for example draws its line at minor repairs rather than by trade, so the same work can land on either side of the rule.
Whether the surface gets walked on
A porch roof used as a balcony, or one reached for maintenance, needs a walkable system and protection. A membrane specified for a roof nobody stands on will not survive being one.
How the work runs
Measure the slope and the area
The pitch determines which systems are even permissible. It is the first number written down and the one that decides everything after it.
Find out what is under the surface
How many coverings, whether the insulation and deck are saturated, and whether the boards are sound. A wet flat roof deck may not be an adequate base for anything laid over it.
Solve the drainage before choosing a membrane
Where the water goes, how it gets there and what happens when the outlet freezes. Tapered insulation, a relocated scupper or a redirected downspout from the roof above often does more for the life of the roof than the choice between EPDM and TPO.
Confirm the permit position for the address
Liverpool names flat roof work explicitly. Other municipalities have to be asked, and a village address is asked at the village office rather than the town that surrounds it.
Tear off, repair the deck and set the falls
Down to sound decking, boards replaced, insulation and taper laid to the drainage plan agreed at step three.
Install and terminate the membrane properly
Field membrane, seams, edge metal, and terminations carried up walls and behind counterflashing rather than stopped at the surface. Terminations are what fails first on this kind of roof.
Detail the junction with the steep roof
The tie-in above is built to take shedding snow and meltwater from a larger area than the flat roof itself, which is the load it actually has to survive.
When you may not need this at all
- If the failure is one seam or one wall flashing on a membrane that is otherwise sound, a repair may hold for years and the re-cover can wait.
- If a downspout from the main roof discharges onto your porch roof and the water sits there, redirecting that discharge may fix the problem for a fraction of the cost of a new membrane.
- Measure before you accept that you have a flat roof at all. A porch at a shallow but real pitch may take shingles perfectly well, and it is the manufacturer's minimum slope that settles it, not the eye.
- A detached accessory structure with no conditioned floor area is excepted from the code's ice barrier requirement, so a detached garage or shed does not carry the same eave detail as the house.
- If the deck is sagging rather than the covering failing, this is a framing problem first. A new membrane over a dished deck simply creates a pond with a longer life.
What is out of scope
- Structural repair and replacement of joists, beams and posts under a sagging flat roof or porch, which is carpentry and engineering rather than roofing.
- Deck and balcony surfacing, railings and guardrail work.
- Large commercial and industrial low-slope roofs. This is residential and small mixed-use work.
- Internal drain plumbing inside the building below the roof outlet.
- Asbestos containing built-up roofing materials, which are sampled first and removed by the separately regulated trade.
- Any claim about how long a particular membrane will last on your building.
Where we arrange this work
Frequently Asked Questions
Can I just shingle my porch roof?
Only if the pitch is at or above the shingle manufacturer's stated minimum slope. Below that, asphalt shingles rely on water running off faster than it can work back under the laps, which on a shallow roof under standing snow it will not. Measure the pitch first. It is the cheapest step in the whole job and the one that decides the rest.
Does flat roof work need a permit?
In the Village of Liverpool, yes, explicitly. The village requires a permit for installation of a new roof covering and for performing any work on a flat roof, including but not limited to hot tar or rubber membrane. Elsewhere in the county it varies: the City of Syracuse treats roofing as its own permit type, the Town of Cicero exempts roofing where no more than two layers are covered, and DeWitt draws its line at minor repairs. Ask the office that governs your address.
Why does my flat roof leak in spring rather than during rain?
Because the failure mode here is ice, not rain. Water ponds, the temperature crosses freezing about 84 days a year, and the ice works into seams, laps and terminations, then the spring thaw sends the meltwater through the openings it made. It is also why standing water on a flat roof is treated as a defect rather than a cosmetic issue.
Should the old roof come off, or can the new one go over it?
That depends on how many coverings are already there and how wet they are. The code does not permit a recover where two or more applications of any covering already exist, or where the existing roof is water soaked or has deteriorated to the point that it is not an adequate base. Saturated insulation under an old flat roof is common, and covering it traps the water in the building.
What should the contract say about the material?
The system and its thickness by name. New York requires a home improvement contract to describe the work and the materials to be provided including make and model, so a line reading rubber roof is not a specification. It should name the membrane type, the thickness, the insulation and how it is attached.
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