The median home in Derby was built in 1967; there are 6,219 of them. 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
Without a permit, Connecticut allows only:
Repairs that are limited to 25 percent of roof covering and building siding within one calendar year.
2022 CSBC, (Amd) R105.2, item 11
A full replacement in Derby is past that line; the town building official issues the permit.
Layers
IRC R908.3.1.1 forbids roofing over two existing layers, over slate or tile, or over a water-soaked roof. 72% of Derby’s homes were built before 1980, so count the layers before comparing quotes.
Source: IRC 2021, Chapter 9 (Pennsylvania edition, UpCodes); 2022 Connecticut State Building Code
Ice barrier
There is no local exception: the state table says “yes.” It runs from the eave to 24 inches inside the exterior wall, more on steep roofs (IRC R905.1.2); check that the quote lists it.
Source: 2022 Connecticut State Building Code; IRC 2021, Chapter 9 (Pennsylvania edition, UpCodes)
Deck joints
Connecticut adds a 4-inch self-adhering strip over all joints of a plywood or OSB deck ((Amd) R905.1.1). It is not needed under a fully adhered membrane, or on board decks under 3 feet wide.
Wind and snow
Derby’s code design values are a 120 mph ultimate design wind speed and a 30 psf ground snow load; it is in Connecticut’s hurricane-prone region. At that wind speed the code calls for asphalt shingles labeled ASTM D7158 Class G or H (Table R905.2.4.1).
Source: 2022 Connecticut State Building Code; IRC 2021, Chapter 9 (Pennsylvania edition, UpCodes) (2022 CSBC, Appendix AY)
Checked against the code text on October 24, 2026. The state’s code edition and the rest of its rules: roof replacement in Connecticut.
Owners live in 3,647 of Derby’s occupied homes, or 62%. Counting by decade, 18% before 1940, 40% before 1960, 72% before 1980 of the housing was in place, and 9% dates from 2000 on. (ACS 2020–2024.)
The housing is 38% detached houses, 18% attached single-family houses (rowhouses, twins and townhouses), 27% buildings of two to four units.
Of the 27 New Haven County municipalities on this site, Derby has the 7th largest share of homes built before 1980: 72%, against a county range of 38% to 87%.
ZIP codes: 06418
| Place | Median built | Before 1980 | Owners | Row, twin | Hail days |
|---|---|---|---|---|---|
| Derby | 1967 | 72% | 62% | 18% | 10 |
| Ansonia | 1954 | 87% | 58% | 5% | 9 |
| Shelton | 1977 | 54% | 77% | 12% | 10 |
| Seymour | 1973 | 61% | 74% | 4% | 11 |
| Orange | 1964 | 73% | 89% | 3% | 9 |
| Woodbridge | 1967 | 67% | 93% | 2% | 8 |
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.
Within 10 miles of Derby, hail of an inch or more was reported on 10 days between 2006 and 2025, the biggest stones 1.75 in on October 4, 2010. The most recent was August 3, 2024.
New Haven County has had 12 federal major-disaster declarations for storms since 2006; the latest was DR-4820, Severe Storm, Flooding, Landslides, and Mudslides (September 2024). (OpenFEMA.)
Storm reports are what observers logged, not a measure of damage to any roof. When wind or hail damage means a new roof.
Useful life is HUD’s planning figure, not a warranty. 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; 38% of homes here are detached | Class G or H at 120 mph design wind (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; 18% 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 (18% of homes here are attached) | Seams at walls and drainage |
Look up the home improvement registration (C.G.S. § 20-420) of anyone pricing a roof in Derby; the law forbids presenting it as an endorsement of workmanship (§ 20-427(b)(6)).
Contracts, deposits and the right to cancel: checking a roofing contractor. What moves the price: new roof cost in Connecticut.
The 25 percent line. A full replacement in Derby is past that line; the town building official issues the permit.
IRC R908.3.1.1 forbids roofing over two existing layers, over slate or tile, or over a water-soaked roof. 72% of Derby’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 Derby was built in 1967, 72% of homes were built before 1980, 62% are owner-occupied.
Hail of 1 inch or larger was reported on 10 days within 10 miles of Derby from 2006 through 2025 (NOAA Storm Prediction Center). A report means hail fell nearby, not that a roof was damaged.
Look up the home improvement registration (C.G.S. § 20-420) of anyone pricing a roof in Derby; the law forbids presenting it as an endorsement of workmanship (§ 20-427(b)(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.