Half of the 2,177 homes in Blairstown were built before 1975. 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
Replacing the covering on a detached one- or two-family house needs no permit and no notice to the town (N.J.A.C. 5:23-2.7). That covers the 92% of Blairstown’s homes that are detached; twins, rowhouses, townhouses and structural work are outside it.
Source: N.J.A.C. 5:23-2.7
Layers
New Jersey deletes the IRC’s reroofing definitions (N.J.A.C. 5:23-3.21(c)2.xxii); its layer rule for existing houses is in the Rehabilitation Subcode, which this site has not read yet. 62% of Blairstown’s homes were built before 1980: ask how many layers yours has and whether the price is for a tear-off to the deck.
Source: N.J.A.C. 5:23-3.21
Ice barrier
New Jersey requires the eave membrane only where January averages 25 °F or colder, which the state says is Sussex County (DCA Bulletin 07-3). In Blairstown it is the installer’s and the manufacturer’s call; ask whether the quote includes it.
Source: N.J.A.C. 5:23-3.21; NJ DCA Bulletin 07-3
Rules as read on October 24, 2026. The state’s code edition and the rest of its rules: roof replacement in New Jersey.
Of 2,114 occupied homes in Blairstown, 2,011 (95%) are owner-occupied. By year built, 21% before 1940, 28% before 1960, 62% before 1980; 11% went up in 2000 or later. (ACS 2020–2024.)
By building type: 92% detached houses.
Of the 22 Warren County municipalities on this site, Blairstown has the 10th largest share of homes built before 1980: 62%, against a county range of 24% to 89%.
ZIP codes: 07825
| Place | Median built | Before 1980 | Owners | Row, twin | Hail days |
|---|---|---|---|---|---|
| Blairstown | 1975 | 62% | 95% | 2% | 9 |
| Hardwick | 1980 | 50% | 87% | 1% | 9 |
| Knowlton | 1978 | 53% | 88% | 3% | 8 |
| Hope | 1972 | 62% | 88% | 2% | 4 |
| Frelinghuysen | 1983 | 43% | 93% | 0% | 4 |
| Liberty | 1968 | 59% | 90% | 1% | 5 |
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.
Since 2006 the National Weather Service has logged hail of 1 inch or larger on 9 separate days within 10 miles of Blairstown; the largest was 1.5 in on May 22, 2014. The most recent was September 7, 2023.
Severe Storm and Flooding (DR-4725, August 2023) is the latest of 10 federal storm declarations covering Warren County since 2006. (OpenFEMA.)
A report says hail fell near Blairstown, not that it damaged a 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; 92% 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 | Simple roofs with long, unbroken slopes | Standing seam that carries its own loads can skip the tear-off (R908.3.1) |
| Slate | 75 years | Older houses; 21% here predate 1940 | Can’t be roofed over; check the framing for the weight |
| Flat roof: EPDM or TPO | 15 years | Porches, additions, low-slope rears | Seams at walls and drainage |
Ask a roofer working in Blairstown for the New Jersey home improvement registration number, which the law requires on contracts and advertising (N.J.S.A. 56:8-138, 56:8-144), and look it up with the Division of Consumer Affairs.
The price side is in what a new roof costs in New Jersey; the paperwork side in checking a roofing contractor.
No permit for a detached house. Replacing the covering on a detached one- or two-family house needs no permit and no notice to the town (N.J.A.C. 5:23-2.7). That covers the 92% of Blairstown’s homes that are detached; twins, rowhouses, townhouses and structural work are outside it.
By the Census Bureau’s American Community Survey (2020–2024), the median home in Blairstown was built in 1975, 62% of homes were built before 1980, 95% are owner-occupied.
Hail of 1 inch or larger was reported on 9 days within 10 miles of Blairstown from 2006 through 2025 (NOAA Storm Prediction Center). A report means hail fell nearby, not that a roof was damaged.
Ask a roofer working in Blairstown for the New Jersey home improvement registration number, which the law requires on contracts and advertising (N.J.S.A. 56:8-138, 56:8-144), and look it up with the Division of Consumer Affairs.
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.