Half of the 2,324 homes in Thornbury Township were built before 1997. The rules below decide how much of the old roof has to come off and what goes under the new one.
New Roofing Costs connects homeowners with independent local roofing contractors. We do not perform roofing work.
This number connects homeowners who are planning a new roof or a full roof replacement with independent local roofing contractors. It is not for leak repairs or patch jobs. The call must come from the homeowner who decides on the roof. Calls may be recorded.
Permit
Pennsylvania’s code leaves residential alterations without structural change to local ordinance (34 Pa. Code § 403.1(b)(8)). Whether Thornbury Township wants a permit is in its own ordinance; ask the township code office before the old roof comes off.
Source: 34 Pa. Code § 403.1(b)
Layers
A new roof may go over one existing layer; with two or more, or over slate, clay or cement tile, everything comes off to the deck (IRC R908.3.1.1). 30% of Thornbury Township’s homes were built before 1980, so count the layers before comparing quotes.
Ice barrier
Whether an eave membrane is a code item depends on the climate table the municipality filled in when it adopted the code (IRC R905.1.2, Table R301.2). The contractor or the township code office in Thornbury Township will know.
Checked against the code text on October 24, 2026. Everything else the state requires: roof replacement in Pennsylvania.
93% of the occupied homes in Thornbury Township are lived in by their owners: 2,074 households, the people this line is for. Counting by decade, 13% before 1940, 20% before 1960, 30% before 1980 of the housing was in place, and 45% dates from 2000 on. (ACS 2020–2024.)
The housing is 79% detached houses, 17% attached single-family houses (rowhouses, twins and townhouses).
45% of homes here were built in 2000 or later. HUD’s useful-life table gives an asphalt-shingle roof 20 years, so roofs on houses from the early 2000s are reaching that age.
Of the 48 Delaware County municipalities on this site, Thornbury Township has the 45th largest share of homes built before 1980: 30%, against a county range of 20% to 98%.
ZIP codes: 19319 · 19342 · 19373
| Place | Median built | Before 1980 | Owners | Row, twin | Hail days |
|---|---|---|---|---|---|
| Thornbury Township, Delaware County | 1997 | 30% | 93% | 17% | 13 |
| Thornbury Township, Chester County | 1994 | 27% | 77% | 26% | 15 |
| Westtown | 1981 | 47% | 83% | 11% | 15 |
| Concord | 1997 | 28% | 71% | 11% | 14 |
| Chester Heights | 1987 | 34% | 76% | 51% | 15 |
| Edgmont | 1991 | 20% | 78% | 22% | 14 |
Median built: median year the homes were built. Before 1980: share of homes built then. Owners: share of homes that are owner-occupied. Row, twin: share of homes that are rowhouses, twins or townhouses. Census ACS 2020–2024. Hail days: days with hail of 1 inch or larger within 10 miles, 2006–2025, NOAA Storm Prediction Center.
NOAA’s storm reports show 13 days since 2006 with hail of at least 1 inch inside a 10-mile circle around Thornbury Township, topping out at 2.5 in on May 22, 2014. The most recent was April 4, 2025.
At the county level, Thornbury Township shares Delaware County’s record of 3 storm disaster declarations since 2006, the newest DR-4618 (Remnants of Hurricane Ida, September 2021). (OpenFEMA.)
Storm reports are what observers logged, not a measure of damage to any roof. When wind or hail damage means a new roof.
Lifespans come from HUD’s capital-needs table, not from a brochure. More in the guides to shingles, metal, slate and flat roofs.
| Material | HUD useful life | Fits a house like | Watch for |
|---|---|---|---|
| Asphalt shingles | 20 years | Most pitched roofs; 79% of homes here are detached | Wind class set by the design wind speed (IRC Table R905.2.4.1) |
| Metal (standing seam, panels) | 50 years | Low pitches and long runs | A complete standing-seam system may go over the old roof (R908.3.1) |
| Slate | 75 years | Older houses; 13% here predate 1940 | Can’t be roofed over; check the framing for the weight |
| Flat roof: EPDM or TPO | 15 years | Low-slope roofs and rear sections (17% of homes here are attached) | Where the roof meets a wall or parapet |
Before signing for a roof in Thornbury Township, get the contractor’s PA registration number: the home improvement law requires registration with the Attorney General above $5,000 a year of such work, and the number on contracts and estimates (HICPA § 3, § 6).
Contracts, deposits and the right to cancel: checking a roofing contractor. What moves the price: new roof cost in Pennsylvania.
Thornbury Township’s ordinance decides. Pennsylvania’s code leaves residential alterations without structural change to local ordinance (34 Pa. Code § 403.1(b)(8)). Whether Thornbury Township wants a permit is in its own ordinance; ask the township code office before the old roof comes off.
A new roof may go over one existing layer; with two or more, or over slate, clay or cement tile, everything comes off to the deck (IRC R908.3.1.1). 30% of Thornbury Township’s homes were built before 1980, so count the layers before comparing quotes.
By the Census Bureau’s American Community Survey (2020–2024), the median home in Thornbury Township was built in 1997, 30% of homes were built before 1980, 93% are owner-occupied.
Hail of 1 inch or larger was reported on 13 days within 10 miles of Thornbury Township from 2006 through 2025 (NOAA Storm Prediction Center). A report means hail fell nearby, not that a roof was damaged.
Before signing for a roof in Thornbury Township, get the contractor’s PA registration number: the home improvement law requires registration with the Attorney General above $5,000 a year of such work, and the number on contracts and estimates (HICPA § 3, § 6).
The full list: before you call.
Checked October 24, 2026. Laws and code editions change; the date says when these were last read at the source.