Detached houses are 13.7% of owner-occupied homes in Philadelphia County, 48,310 houses (ACS 2020–2024), and they are concentrated in a few parts of the city. Twins are counted by the Census Bureau together with rowhomes as single-family attached, so the numbers below show detached houses only.
| ZIP | Neighborhoods | Owner-occupied homes that are detached | Median year built |
|---|---|---|---|
| 19118 | Chestnut Hill | 47.5% (1,123) | 1947 |
| 19115 | Bustleton | 46.1% (4,278) | 1967 |
| 19116 | Somerton | 41.4% (3,450) | 1970 |
| 19114 | Torresdale, Morrell Park | 27.4% (2,411) | 1969 |
| 19128 | Upper Roxborough, Andorra | 27.2% (2,831) | 1961 |
| 19126 | East and West Oak Lane | 26.5% (1,165) | 1942 |
| 19119 | West and East Mount Airy | 25.9% (2,064) | 1938 |
Census Bureau ACS 2020–2024, by ZCTA. Neighborhood names are from the City's neighborhoods map.
Two kinds of pitched roof
The Far Northeast houses (19114, 19115, 19116) are mostly from the 1960s and 1970s, the median years built there. Chestnut Hill and Mount Airy are older: in 19119, 56.8% of homes date from 1939 or earlier, and a pitched roof there may be slate, which changes the job (see slate roofs).
What the City's standard says about shingles
The EZ re-roofing standard L&I uses for roof covering replacement sets these rules for a shingle roof:
- Slope. Asphalt shingles only on slopes of 2 in 12 (17%) or steeper. Many twins and detached houses have a low-slope section over a rear addition or porch, which gets a membrane instead.
- Wind class. Shingles must meet ASTM D3462 and be classified for wind resistance (D, G or H under ASTM D7158, or A, D or F under ASTM D3161). The class is printed on the bundle wrapper; ask for it in the estimate.
- Drip edge. At eaves and gables, extending at least 1/4 inch below the sheathing and 2 inches back onto the deck, fastened at least every 12 inches and lapped at least 2 inches.
- Fire class. At least Class B under ASTM E108 or UL 790 for most houses.
- Layers. Every existing layer comes off first if the roof is water-damaged or deteriorated or already has two or more coverings.
The code adds that on slopes from 2 in 12 up to 4 in 12, asphalt shingles need a double layer of underlayment (IRC 2021 R905.2.2).
The twin's shared ridge
A twin has one roof over two houses. When one owner replaces their half, the new shingles or membrane end at the party line, and the joint with the neighbor's half has to be closed and flashed. Mention it on the call: a contractor plans the ridge and the party-line detail differently when the other half is old.
How long a shingle roof lasts
HUD's useful-life table, a planning tool for capital spending, gives asphalt shingles 20 years, metal 50 and slate 75. A "30-year" shingle is a warranty term, not a service life. Whether your roof needs replacing is for an inspection to say; when to replace lists what to look at.
Permit
The replacement still needs the City's EZ permit ($69 on a one- or two-family house, plus surcharges). See roof permits.