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Flat Roof Replacement in Philadelphia, PA

Stripping and rebuilding a low-slope roof on a rowhouse, twin or loft conversion, with the drainage and parapet details redesigned rather than reused.

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  • Flat and low-slope rowhouse roofs
  • Parapet, scupper and drain repairs
  • Twins, slate and storm-wind damage
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Flat Replacement

Flat Roof Replacement: what it covers

Quick answer

Flat roof replacement strips a low-slope roof to the deck, renews what is wet or soft, and rebuilds the covering with the fall, the drainage and the parapet details designed as one. On a Philadelphia rowhouse that fall is a quarter inch per foot toward the outlet. Call (833) 751-2102 for a survey.

Flat Roof Replacement illustration for Philadelphia, PA

Replacement is the point where patching stops being worth it. A roof with wet insulation in several bays, splitting membrane in the open field and no usable fall will keep producing leaks wherever it is sealed, because the problem is the whole assembly rather than the last hole.

The opportunity is that everything becomes adjustable at once. With the old covering off you can correct the fall, resize or relocate the outlet, take the upstands to a proper height and deal with every redundant penetration left by previous work.

Philadelphia Roofing has a local roofer survey the roof and the deck first, because what is underneath decides the scope. Older roofs here are generally built-up tar and gravel; replacements are typically a modified bitumen, EPDM or TPO membrane, and no brand of either appears on this site.

Service area
Philadelphia & Philadelphia County
Availability
Phones answered 24/7
Warning signs

Signs you need flat roof replacement

Keep off a roof during a tear-off and keep the area below it clear. Debris, fixings and hot or sharp material come off the edge of a parapeted roof with nothing to catch them, and the only barrier is often a knee-high wall. Move vehicles, bins and anything stored against the back of the house before the crew arrives, and keep children and pets indoors on working days. Inside, expect noise and vibration through the top floor and take down anything hanging on a top-floor wall. Questions about the schedule go to (833) 751-2102 rather than being asked from a ladder.

  • Leaks appearing in new places each season rather than returning to one spot
  • Membrane that has split, shrunk or gone brittle across open areas of the roof
  • A deck that feels soft or dishes underfoot over more than one bay
  • Water that still ponds days after rain even once the outlet is clear
  • Three or more generations of patching visible on the same roof
  • Insulation that squelches or stays wet when a test cut is taken
  • Gravel ballast worn through to the felt over much of an older built-up roof
Options

Types and options for flat roof replacement

Rowhouse and twin roofs

A single-house roof bounded by parapets and party walls, usually with one outlet. The work is small in area and detail-heavy, and most of the skill is in the perimeter rather than the field.

Loft and converted building roofs

Wider decks with several outlets, changes in level from additions over the decades, and often rooftop equipment. Each step and each penetration is its own detail, and the ages of the joints differ across one roof.

Replacement with a roof deck or terrace above

Where a terrace, pavers or a deck structure sits over the membrane, the waterproofing has to be right before anything goes back on top, and the fixings for what goes above have to be designed rather than driven through the new sheet.

One call and it gets handled.

Most flat roof replacement calls are scheduled the same day when a technician is free, and you approve the price before any work starts.

Call (833) 751-2102Get a quote

When is replacement the honest answer instead of repair?

When the deck or insulation is wet over an area, the membrane has failed in open field rather than at a joint, or the fall and outlet cannot be made to work with the covering down. Isolated damage over a dry deck is a repair, and a roofer should say which of those your roof is.

A test cut settles the argument. If the insulation under the sheet is saturated across several bays, the water in it is not coming out and anything laid over it is trapping it. If the cut is dry and the damage is a single tear, you are being sold the wrong job.

Ask for photographs of the cut and the probe readings. On a roof that has already been patched three or four times, the case for replacement is usually the patching history as much as the material: each previous repair tells you where the assembly keeps failing. If it is a repair, flat roof repair covers that work.

What changes about the drainage during a replacement?

Everything can be reconsidered. The city's homeowner guide gives a minimum fall of a quarter inch per foot to the low point, and a replacement is the one chance to restore it with tapered build-up, re-cut a saddle, enlarge an outlet or add a second one where a single drain has never coped.

The two drainage routes on a rowhouse are both on the table: a drain through the cornice or parapet as a scupper joining an outside downspout, or a gutter along the facade, which is more common at the rear. Which one a roof has is a product of how the house was built, and changing it is a decision rather than a detail.

An overflow is worth discussing as well. A single blocked outlet on a parapeted roof turns the whole roof into a tank, and a secondary path at a known height means a blockage shows itself as water down an outside wall instead of as a ceiling stain. The roof drain and scupper repair page explains how those outlets behave.

Does a replacement need historic review?

It can on a designated property. The Philadelphia Historical Commission's roofs guidance favours work that is inconspicuous from the public right-of-way, and flat roofs hidden behind a parapet are generally treated more simply than street-facing slopes. The Commission confirms what applies to a specific address.

The order matters: confirm designation and the review question before the specification is finalised, because review can come before L&I issues the permit. A membrane you cannot see from the pavement is a different proposition from altering a visible cornice or mansard.

Larger and commercial buildings can fall under different city rules again, and L&I answers for the address. Our guides on roof permits in Philadelphia and slate and historic roofs set out both tracks.

How is a replacement staged on a narrow attached house?

Carefully, and with the neighbours informed. There is no driveway, often no rear access, and the skip has to sit on a street with cars on both sides. Material goes up and tear-off comes down through a single point, and on stepped blocks the adjoining roofs sit at different levels.

Practically that means agreeing the staging point, the skip position and the working hours before anything is ordered, and telling the adjoining owners because the party-wall upstands on both sides of your roof are part of the job.

It also means the quote should name access as a line of work rather than an afterthought. In the stepped hillside blocks above the Schuylkill in Manayunk and Roxborough and on the trinity-sized streets of Queen Village, access is genuinely one of the bigger variables in the job.

Our process

How our flat roof replacement visit works

  1. Survey, probe and take a test cut

    The roofer measures the roof, maps the fall, and takes a small cut through the build-up to see the layers and whether the insulation is wet. That cut is what separates a replacement quote from a guess.

  2. Design the drainage before the covering

    Where the water will go is settled first: the position and size of the drain or scupper, whether a rear gutter is involved, and how the fall will be achieved. A new membrane laid over the old drainage repeats the old ponding.

  3. File the permit and plan access

    Most roof replacements need a permit, which the contractor files through Licenses and Inspections in the city; the city operates an EZ permit with no plans and says most applications are processed in five business days. Where materials, the hoist and the skip go is agreed with you and, on a row, with the neighbours.

  4. Tear off and inspect at the right moment

    The old covering comes off down to the deck. For a minor permit the L&I inspection happens after the old roofing is removed and the new material is on site, and the new membrane or coating should not be installed until that inspection passes.

  5. Rebuild deck, details and membrane

    Soft decking is replaced, insulation and any tapered build-up goes down, then the membrane with upstands taken to height at every parapet and party wall, new flashings, a new drain or scupper detail and sealed collars at each penetration.

  6. Test, record and hand over

    The drainage run is flooded or wetted and watched, the finished details are photographed, and you are walked through what was found and what was changed, so the next roofer has a history to work from.

Philadelphia County

Why flat roof replacement is different in Greater Philadelphia

This is the city's default roof. Multi-floor row homes are about 70% of the housing stock by one estimate from a Philadelphia architecture-and-design body, and around three quarters of them are over fifty years old, so a full membrane replacement in South Philadelphia or Fishtown is routine work rather than a specialist commission.

Loft and factory conversions change the scale. In Northern Liberties, Fishtown and along the Schuylkill in Conshohocken, former industrial buildings carry wide membrane decks with multiple outlets and later additions, and newer townhouse infill often has a roof deck over the waterproofing.

Outside the city the paperwork moves. Delaware and Montgomery County townships and boroughs administer their own permits locally, and Camden, Pennsauken, Collingswood and Cherry Hill issue theirs as New Jersey municipalities rather than through Philadelphia L&I.

Where we work

Flat Roof Replacement across Philadelphia County

Not sure if you're covered? Check your ZIP code.

Related

Flat Roof Repair

Repairs to flat and very low-slope membrane roofs on Philadelphia rowhouses, twins and converted buildings, starting at the drainage path.

Rowhouse Roof Replacement

Replacing the roof on an attached house, where the party walls, the neighbours and the street are as much of the job as the covering.

Parapet and Cornice Flashing

Sealing the upstands, copings and party-wall terminations where a Philadelphia rowhouse membrane meets masonry.

Guides

Read before you book

FAQ

Flat Roof Replacement FAQs

Can a new membrane go over the old one?

It leaves wet insulation and a failed deck in place and hides both. City guidance for a covering replacement on a one- or two-family house describes removing the old covering and having it inspected before new material goes down, and that is the approach taken here.

How long is the roof open?

A single rowhouse roof is normally a short job, but it depends on the deck and the weather, and the permit inspection has to land between tear-off and the new membrane. The schedule is agreed before the skip arrives rather than promised in advance of a survey.

Which membrane will be used?

That is a site decision based on the roof, its drainage and what is already there, and no product or brand names appear on this site. Replacements in this housing type are generally modified bitumen, EPDM or TPO.

What about my roof deck or the pavers up there?

They come off, because waterproofing under a terrace has to be sound before anything is reinstated. How they go back, and how anything is fixed through or around the new membrane, is part of the scope rather than an extra.

Will you talk to my neighbours?

Yes, and it is worth doing early. The party-wall upstands are shared details, access may cross an adjoining roof, and a neighbour who knows the dates is far easier to work beside than one who finds out when the skip lands.

What goes wrong when a replacement is done badly?

Usually the perimeter. Upstands finished too low, a drain flange sealed rather than properly detailed, or the old fall left untouched will produce leaks on a brand-new roof, which is why the details and the drainage matter more here than the field of the sheet.

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