Seismicity
Lowlevel 2 out of 5
France is divided into five seismicity zones, from 1 (very low) to 5 (high, in the Antilles).
For a property: In this zone, no seismic rules apply to detached houses.
Population
263
+29.6% since 2012
Public data cross-referenced (DGFiP, INSEE, ADEME), recorded on October 4, 2026.
Rents
Reference rents (2025)
| Property type | Median rent (€/m²) | Range (€/m²) |
|---|---|---|
| Flats, all sizes | 11.3 | 8.9 – 14.3 |
| Flats with 1-2 rooms | 12.9 | 10.2 – 16.3 |
| Flats with 3 or more rooms | 9.3 | 7.3 – 11.9 |
| Houses | 8.7 | 6.4 – 11.8 |
How to read this table. This is a predicted advertised rent, including service charges, per square metre per month — not the rent signed in the lease. The range brackets the estimate: most listings in the municipality fall within it. These estimates are recalculated every year with a new model, so two releases cannot be compared with each other.
Estimations ANIL, à partir des données du Groupe SeLoger et de leboncoin · Rent map 2025
Energy performance of the housing stock
Breakdown of homes in Île-de-Sein by energy performance certificate (EPC) band. Since the loi Climat & Résilience (Climate and Resilience Act), it is this band that determines whether a home may be let.
Breakdown of energy performance certificates in Île-de-Sein
D
E
F
G
- A00.0%
- B00.0%
- C25.3%
- D1026.3%
- E923.7%
- F821.1%
- G923.7%
38 homes surveyed. 44.7% of the surveyed housing stock is rated F or G — that is 17 homes already affected, or about to be, by the letting ban. Including band E, targeted for 2034, the share rises to 68.4%.
Rental ban timeline
- 2025Gbanned
- 2028Fbanned
- 2034Ebanned
2021 loi Climat & Résilience (Climate and Resilience Act) — applies to new leases.
Source: ADEME, energy performance certificate database · recorded on October 4, 2026
Why this breakdown matters. A dwelling rated G can no longer be let under a new lease since 1st January 2025; F will follow in 2028 and E in 2034. A commune whose stock is largely rated F or G therefore faces a wall of renovation work, or an exit from the rental market.
Note: these figures cover surveyed homes, not the entire stock. A survey is only required on sale or letting, so homes occupied for a long time are under-represented.
Housing stock
Île-de-Sein has 396 dwellings at the 2023 census, of which 43.8% are main residences; the rest is split between second homes and vacant dwellings.
What are dwellings used for?
- Main residences44.3%
- Second homes and occasional dwellings47.6%
- Vacant dwellings8.1%
Source: INSEE, census
Who lives in main residences?
- Tenants4918.0%
- Owner-occupiers22482.0%
Source: INSEE, census
Between 2012 and 2023, the population changed by +29.6% while the housing stock grew by only +11.4%: pressure on existing housing is increasing.
| Dwellings (2023) | 396 |
|---|---|
| Households | 173 |
| Île-de-Sein | Finistère | Bretagne | France | |
|---|---|---|---|---|
| Main residences2023 | 44.3%−38.1 pts vs France | 79.9% | 80.2% | 82.4% |
| Second homes2023 | 47.6%+37.8 pts vs France | 13.5% | 13.1% | 9.8% |
| Vacant dwellings2023 | 8.1%≈ France | 6.6% | 6.6% | 7.8% |
| Residents who own their home | 82.0%+21.2 pts vs France | 73.2% | 70.7% | 60.8% |
| Tenant residents | 18.0%−19.4 pts vs France | 25.5% | 28.1% | 37.4% |
Under each value for the municipality: its gap with France. For a rate, the gap is in percentage points (12.4% vs 7.8% = +4.6 pts); for an amount or a ratio, as a percentage of the national value.
Dwellings authorised for construction in Île-de-Sein
View the data
| Year | Flats (multi-dwelling buildings) | Detached houses | Total |
|---|---|---|---|
| 2021 | 0 | 1 | 1 |
| 2022 | 0 | 0 | 0 |
| 2023 | 0 | 0 | 0 |
| 2024 | 0 | 1 | 1 |
| 2025 | 0 | 1 | 1 |
| 2026* | 0 | 0 | 0 |
Source: Sit@del, ministry responsible for housing · recorded on October 4, 2026
Sources: INSEE (census), Sit@del · recorded on October 4, 2026
Population and households
| Population | 263 |
|---|---|
| Households | 173 |
| People per household | 1.52 |
Change in the population of Île-de-Sein
20040060080019681982199920122023263 inhab.
Between 2012 and 2023, the population changed by +29.6%.
Source: INSEE, population census · recorded on October 4, 2026
Age breakdown
- Under 18145.2%
- 18 to 2462.1%
- 25 to 2983.1%
- 30 and over23589.5%
Source: INSEE
What do people aged 15 and over do?
- Employed workers9136.0%
- Unemployed155.9%
- Retired people13051.1%
- Pupils and students51.9%
- Other economically inactive135.1%
Source: INSEE
| Île-de-Sein | Finistère | Bretagne | France | |
|---|---|---|---|---|
| Population trend2012-2023 | +29.6%+25.2 pts vs France | +3.6% | +6.6% | +4.4% |
| Median age2023 | 62.2 years+19.7 yrs vs France | 46.1 years | 44.9 years | 42.5 years |
| Share aged under 252023 | 7.4%−21.4 pts vs France | 26.4% | 27.6% | 28.8% |
| Share aged 65 and over2023 | 44.1%+22.8 pts vs France | 24.8% | 23.8% | 21.3% |
| People per household2023 | 1.5−30% vs France | 2.1 | 2.1 | 2.2 |
Under each value for the municipality: its gap with France. For a rate, the gap is in percentage points (12.4% vs 7.8% = +4.6 pts); for an amount or a ratio, as a percentage of the national value.
Why the number of people per household matters. A household is everyone who shares the same dwelling. The fewer people it has, the more demand shifts towards small homes — studios and one-bedroom flats, sought by people living alone, students and retirees; the more it has, the more demand shifts towards family homes with three or more rooms.
In Île-de-Sein, a household has 1.52 people on average, compared with 2.17 in France: more people living alone and couples without children, so demand leans more towards small units.
Source: INSEE, population census · recorded on October 4, 2026
Income and employment
| Île-de-Sein | Finistère | Bretagne | France | |
|---|---|---|---|---|
| Unemployment rate (aged 15-64)2023 | 14.1%+3.1 pts vs France | 9.8% | 9.3% | 11.0% |
| Activity rate (aged 15-64)2023 | 77.1%+1.4 pt vs France | 74.9% | 75.7% | 75.7% |
| Share of retired people (aged 15 and over)2023 | 51.1%+23.0 pts vs France | 33.5% | 32.3% | 28.1% |
| Share of pupils and students (aged 15 and over)2023 | 1.9%−5.7 pts vs France | 7.0% | 7.2% | 7.6% |
Under each value for the municipality: its gap with France. For a rate, the gap is in percentage points (12.4% vs 7.8% = +4.6 pts); for an amount or a ratio, as a percentage of the national value.
How to read these figures. The standard of living is a household's disposable income (salaries, pensions and benefits, after tax) divided by its number of consumption units: the first adult counts as 1, other people aged 14 or over as 0.5, and each child as 0.3. It allows a single person and a family to be compared.
The poverty rate is the share of residents whose standard of living is below 60% of the national median. INSEE does not publish it for small communes, for reasons of statistical confidentiality: its absence is not a zero.
The unemployment rate here is the census one: people who declare themselves without work and looking for it, among the economically active aged 15 to 64. It is higher than INSEE's quarterly rate, which follows a stricter international definition.
Sources: INSEE (census, Filosofi) · recorded on October 4, 2026
Economic fabric
Number of businesses located in Île-de-Sein
222420142016201820202022202425
25 businesses in 2024, compared with 21 in 2014: +19.0% over the period.
View the data
| Year | Businesses |
|---|---|
| 2014 | 21 |
| 2015 | 22 |
| 2016 | 21 |
| 2017 | 23 |
| 2018 | 21 |
| 2019 | 22 |
| 2020 | 22 |
| 2021 | 21 |
| 2022 | 23 |
| 2023 | 25 |
| 2024 | 25 |
Source: INSEE, business demography information system · recorded on October 4, 2026
| Île-de-Sein | Finistère | Bretagne | France | |
|---|---|---|---|---|
| Number of businesses2024 | 25 | 75,862 | 303,520 | 6,437,729 |
| Change in the number of businesses2019-2024 | +13.6%−11.4 pts vs France | +24.8% | +27.1% | +25.0% |
| Businesses per 1,000 inhabitants2024 | 95.1−2% vs France | 81.3 | 88.0 | 97.3 |
Under each value for the municipality: its gap with France. For a rate, the gap is in percentage points (12.4% vs 7.8% = +4.6 pts); for an amount or a ratio, as a percentage of the national value.
In what form do businesses operate?
- Sole traders3959.1%
- SAS and SASU34.5%
- SARL and EURL1218.2%
- Civil companies, including SCI1015.2%
- Other forms23.0%
Sources: INSEE (SIRENE register), INPI (national business register) · recorded on October 4, 2026
Registrations and insolvency proceedings
* current year, incomplete
From 2021 to 2025, 10 registrations for 2 insolvency proceedings.
View the data
| Year | Registrations | Insolvency proceedings |
|---|---|---|
| 2021 | 2 | 2 |
| 2023 | 1 | 0 |
| 2024 | 1 | 0 |
| 2025 | 6 | 0 |
| 2026* | 3 | 0 |
Source: BODACC, official bulletin of civil and commercial announcements · recorded on October 4, 2026
Sources: INSEE, BODACC · recorded on October 4, 2026
Local taxation
In 2024, the overall property tax rate on built properties is 15.97% in Île-de-Sein.
| Rate voted by the commune | 15.97% |
|---|---|
| Overall rate on built properties (total) | 15.97% |
| Overall rate on undeveloped land | 0.00% |
Worked example
A dwelling with a cadastral rental value of €3,000 has a tax base of €1,500: the law sets it at half the rental value. In Île-de-Sein, its property tax (taxe foncière) is €1,500 × 15.97% = €240 a year.
These amounts are before the collection charges retained by the State. Your property's rental value is shown on your property tax (taxe foncière) notice.
| Year | Communal rate | Overall rate on built properties | Household waste |
|---|---|---|---|
| 2021 | 15.97% | 15.97% | — |
| 2022 | 15.97% | 15.97% | — |
| 2023 | 15.97% | 15.97% | — |
| 2024 | 15.97% | 15.97% | — |
The overall rate remained stable between 2021 and 2024.
How to read these rates. Property tax (taxe foncière) is calculated by multiplying the property's tax base by the overall rate: this is the figure to compare between communes, not the communal rate alone. Since 2021, départements no longer collect property tax on buildings; their former share is included in the communal rate.
A high rate does not mean a high tax. The cadastral rental value is not the market rent: it is an administrative estimate based on 1970 rents, revalued each year by a national coefficient. In a town with old, low rental values, a 50% rate can cost less than a 25% rate elsewhere.
Commune subject to the tax on vacant dwellings
Île-de-Sein is on the list of communes where the housing market is tight. A dwelling left empty for more than a year is subject to the tax on vacant dwellings there, and the municipal council may raise the housing tax on second homes by 5% to 60%.
The commune has not voted a surcharge on the housing tax on second homes.
Source: DGFiP, local taxation for individuals (2024 scale) · recorded on October 4, 2026
Living environment
Services and shops in the commune
- Health
- General practitionerPharmacy
- Shops
- Grocery or convenience store
- Education and early years
- Nursery or primary school
- Services and transport
- Post office or postal pointBank
How to read this list. It shows the services for which at least one establishment is recorded in the commune. A service that does not appear is not necessarily absent: INSEE does not locate every facility with the same precision, and the list only includes the main ones.
Source: INSEE, permanent facilities database 2024
Fixed internet
- Dwellings and premises connectable to fibre0.0%0 connectable out of 483
Connectable means that optical fibre reaches the building or the street and a subscription can be taken out, not that the dwelling is already subscribed.
Source: ARCEP, fibre rollout · situation as at June 2026
Natural and technological risks
The risks identified by the State in the territory of Île-de-Sein, what they mean, and what they change for a property.
Radon potential
Significant potentiallevel 3 out of 3
Radon is a natural radioactive gas that rises from granitic and volcanic soils and can build up in poorly ventilated rooms, especially on ground floors and in basements.
For a property: At this level, the seller or landlord must inform the buyer or tenant. Good ventilation and a sealed ground floor are usually enough to reduce exposure.
A prevention plan is not a bad sign in itself. It shows that the risk is mapped and regulated; it is its absence for a known hazard that should raise questions.
This page describes the commune, not an address. Before a sale or a letting, the seller or landlord must provide a risk statement drawn up for the property. You can obtain one free of charge for any address at georisques.gouv.fr.
Source: Géorisques, Ministry of Ecological Transition · recorded on October 4, 2026