What a roof replacement costs around Philadelphia
Two quotes on the same house can be thousands of dollars apart, and it is almost never because one contractor is greedy. It is because the two numbers include different work, and on housing this old, the work that differs is nearly always hidden: what is under the covering, and what happens at the edges.
The lines that move the number
Layers first: code allows two, and on sixty-year-old suburban stock a third is a common find, which turns a recover into a full strip. Decking second, priced per sheet, and here comes the local wildcard. Anything roofed in slate a century ago sits on spaced sheathing: gapped boards that modern shingle cannot be nailed to. Sheeting over them is a real material and labor line, and a quote that never mentions it either has not looked or is planning to raise the price mid-job.
Then the details this housing makes likely. The porch or low-slope section, which needs different material than the main field and is the most commonly omitted item in a local quote. The party-wall tie-in on rows and twins. Chimney step and counter-flashing, replaced rather than reused, cut into the mortar rather than caulked to the brick. Valley metal, which decades of leaf load under a mature canopy has usually finished. And ventilation, which on a pre-1960 house often has to be created rather than corrected.
Why timing changes the quote
The working season here runs March into December, long by our standards, but that does not mean the calendar is open. Spring and early autumn are what everyone wants, and the specialist trades who handle slate, steep old framing and attached-house tie-ins are a small pool that books months ahead.
The practical consequence: quotes gathered in January and February get the attention and the schedule choice, while a call in September gets whoever is free. On plat-built streets where a whole development is coming due at once, being a season ahead of the neighbors is worth real money.
Before you sign, make every bidder answer
- How many layers is this bid assuming?
- The layer count is the first fork in the price, and disposal weight follows it. On older stock a third layer is common enough that the answer should come from the roof rather than a rule.
- What is the per-sheet decking price, and what if the sheathing is spaced?
- Spaced boards under a former slate roof are a real cost that a thin bid silently omits. Ask for both the sheet rate and what happens if the sheathing turns out to be gapped.
- Is the porch or low-slope roof included, and in what material?
- It runs on its own clock and needs its own material. A quote that covers only the main field has priced the easy part of the house.
- How does the new covering tie into an attached neighbor?
- Attached housing is the norm here, and the party-wall junction is a detail rather than an afterthought. A bidder who names it has done this before on your kind of house.
- Is chimney counter-flashing cut into the mortar, or caulked to the face?
- Caulk on brick is a repair with a short horizon. Cut and set into the mortar joint is what survives the mid-Atlantic freeze-thaw cycle, and it is worth insisting on in writing.
- Is any attic ventilation being created here, and of what kind?
- On a house of this age, ask whether there is any ventilation at all today. Creating intake and exhaust during a replacement costs a fraction of adding them to a finished roof.
Next step: Slate or shingle: the decision