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Connecticut · The 50% Rule
In Connecticut,
your town writes the rule. There is no statewide 50% statute for private renovation. The threshold sits in each town’s flood hazard overlay — and the lookback window is the variable that decides everything. Town-Set Lookback Coastal Site Plan Review Height Variance Risk
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Seaport Advisory Briefing
Two towns, same
house, different answer. A one-year lookback lets genuinely separate projects stand apart. A ten-year or life-of-structure lookback adds up everything you have ever done. Same 50%, entirely different renovation. What Sets The Rule
44 CFR 59.1 — federal definition
Town flood hazard overlay — the window CGS 8-2l — floodplain encroachment PA 25-33 — coastal review, 2025–26 |
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Find the window
Ask the town one question: over what period do you add up improvement costs? Everything else follows from the answer. |
Value the structure
The 50% runs against the building alone, land excluded. Some towns name the assessor’s figure; others accept an appraisal. |
Check the height math
Connecticut has no statewide relief. Elevating can push a house past the district height limit and into a variance. |
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Two questions to answer first
Whether the property sits in a mapped flood zone, and whether it sits inside the coastal boundary. The first can be looked up. The second cannot be settled online — and the reason why is worth understanding.
Why the coastal boundary has no online answer
The legal coastal boundary is the set of mylar maps adopted town by town by the DEEP Commissioner, later revised by twenty-two coastal towns under the Coastal Management Act. DEEP’s own GIS layer carries an explicit warning that it does not replace those legal maps and may not be used for legal determinations. Use the mapping links above to screen. For an answer you can rely on, ask the town’s zoning office to check the parcel against its adopted coastal boundary map. That is a five-minute phone call and it is the only source that governs. State-level help: the CT DEEP flood management program runs the state side of the National Flood Insurance Program and can point you to the right municipal contact. Southeastern Connecticut towns also have a regional SCCOG flood management resource. The statutory test, so you know what you are looking at: the boundary runs inland to whichever is furthest — the landward extent of the 100-year coastal flood zone, a thousand feet from mean high water, or a thousand feet from the inland edge of tidal wetlands. If a parcel is anywhere near one of those, assume it is inside until the town says otherwise. |
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Start Here
Enter the value of the structure only, then your planned spend. Pick a county and town to load what we have confirmed locally. $
Building only, land excluded. Not the purchase price.
$
$
Permitted work already done within the lookback period below.
Groton and Stonington each have two jurisdictions. Pick carefully.
This is the single most important input. Ask the zoning office directly.
The coastal area management boundary. Changed materially in October 2025.
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Enter a structure value to begin
Your position against the 50% line, what we have confirmed for your town, and what still needs a phone call will appear here.
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