Rear dormers for terraced houses
26.4% of households here live in terraced houses. Dormers are the most common choice for terraces, because they add headroom without major structural changes.
Slough Borough Council
Loft Conversions in Slough
15.8% of households in the Slough area were short of at least one bedroom at the 2021 Census, against 5.3% across Berkshire.
26.4% of households in the Slough area live in terraced houses, against 21.7% across Berkshire.
Planning and building control here are handled by Slough Borough Council.
Slough homes at a glance
Type of home (households)
Detached10.5% in Slough, (Berkshire 26.6%)
Semi-detached29.5% in Slough, (Berkshire 27.7%)
Terraced26.4% in Slough, (Berkshire 21.7%)
Flats33.4% in Slough, (Berkshire 23.2%)
Bungalows (share of properties)2.4% in Slough, (Berkshire 5.1%)
When homes were built
Before 19195.2% in Slough, (Berkshire 12.6%)
1919 to 193921% in Slough, (Berkshire 9.6%)
1945 to 197230% in Slough, (Berkshire 29.2%)
1973 to 199922.3% in Slough, (Berkshire 27.8%)
2000 or later21.5% in Slough, (Berkshire 20.8%)
- Median home price, 2025
- £397,000
- Berkshire £435,000
- Households short of a bedroom
- 15.8%
- Berkshire 5.3%
- Most common type of house
- Semi-detached
- 29.5% of households
Sources: ONS 2021 Census (TS044 accommodation type, TS052 occupancy rating, TS061 travel to work), households; VOA Council Tax stock of properties, 31 March 2025 (build period and bungalows, rounded by the VOA, homes with unknown build period excluded); HM Land Registry Price Paid Data, standard sales in 2025. Area defined by ONS built-up areas and 2021 census neighbourhoods (LSOAs).
Loft conversion costs in Slough
Build costs for Berkshire, from published cost guides adjusted for the South East. They are estimates to help you budget, not quotes, and we review them regularly.
| Conversion type | Floor area | Typical build cost | Build time |
|---|---|---|---|
| Velux or rooflight | 30m² | £26,000 to £39,000 | 4 to 6 weeks |
| Rear dormer | 30m² | £46,000 to £78,000 | 10 to 12 weeks |
| Hip to gable | 30m² | £57,000 to £91,000 | 10 to 14 weeks |
| Mansard | 30m² | £57,000 to £104,000 | 12 to 16 weeks |
| Bungalow | 50m² | £72,000 to £114,000 | 10 to 12 weeks |
Ranges, not quotes. Build cost only: excludes VAT, professional fees, planning and building control. Last updated September 2026.
Sources: Checkatrade, Loft conversion cost: 2026 UK price guide (March 2026 (table), August 2026 (breakdown)); Homebuilding & Renovating, Loft conversion costs (Tim Phillips, quantity surveyor) (29 July 2026).
A typical 30m² rear dormer (£46,000 to £78,000 to build, before VAT and fees) is about 10% to 16% of the 2025 median price of a semi-detached house in the Slough area (£478,000).
Work out a cost for your own loft with the calculator, or read the full cost guide.
Which conversion suits Slough homes
These are tendencies based on the local mix of homes, not advice for your house. A specialist survey confirms what your roof allows.
House prices and value added in Slough
| Type | Median | Sales | Value added* |
|---|---|---|---|
| Detached | £600,000 | 89 | £72,000 to £150,000 |
| Semi-detached | £478,000 | 250 | £53,000 to £119,000 |
| Terraced | £405,000 | 333 | £41,000 to £101,000 |
| Flat or maisonette | £240,000 | 290 | - |
| Year | Median | Sales |
|---|---|---|
| 2021 | £345,000 | 1440 |
| 2022 | £360,000 | 1269 |
| 2023 | £380,000 | 909 |
| 2024 | £385,000 | 964 |
| 2025 | £397,000 | 962 |
| 2026 (to date) | £405,000 | 338 |
* A rough guide, not a valuation. The low figure applies Nationwide's estimate for adding a fourth bedroom to this type of house (10% terraced, 11% semi-detached, 12% detached); the high figure applies its "as much as 25%" for a large bedroom and bathroom. Nationwide's figures come from its 2023 national model, not Berkshire data. Prices are HM Land Registry standard market sales; medians from fewer than 20 sales are not shown.
Planning in Slough
Many loft conversions can be built without planning permission under permitted development rights, within limits: up to 40m³ of extra roof space for a terraced house and 50m³ for other houses, nothing higher than the existing roof, and nothing beyond the front roof slope facing a road. These rights do not apply in conservation areas. Read more in our planning guide for Slough Borough.
Conservation areas (4)
If your home is in one of these, a dormer or other roof enlargement will normally need planning permission:
- St Bernard's School
- St Mary's Church, Langley
- Sussex Place and Clifton Road
- Upton Park and Upton Village
From each council's official list. Check Slough Borough's conservation areas. Boundaries can change, so check your address on the council's map.
Building control fees
Every loft conversion needs building regulations approval. The council's published charges for a loft conversion (including VAT):
Slough Borough Council
- Loft conversion: £726 full plans, £726 building notice
Effective from 1 September 2019. The page says these charges are effective from 1 September 2019, so they may be out of date. Check the current charge with the council. Source.
Areas and postcodes we cover
This page covers Slough. Postcode districts: SL1, SL3, SL2.
The area follows the ONS built-up areas for Slough; the postcode districts are the ones that make up at least 5% of home sales here since 2021. Some districts also reach neighbouring areas.
Loft conversions in Slough: questions
How much does a loft conversion cost in Slough?
As a guide, a typical 30m² rear dormer costs £46,000 to £78,000 to build in Berkshire, before VAT and fees, based on published cost guides adjusted for the South East. Velux conversions cost less and hip-to-gable or mansard conversions more. Slough Borough's building control charge for a loft conversion is £726 for a full plans application, including VAT. Every house is different, so get quotes before you budget.
Do I need planning permission in the Slough conservation areas?
Usually, yes. Permitted development rights for roof enlargements, such as dormers, do not apply in conservation areas, so you will normally need planning permission. There are 4 conservation areas in the Slough area, including St Bernard's School, St Mary's Church, Langley and Sussex Place and Clifton Road. Check your address on the council's map. Outside conservation areas, many loft conversions can go ahead under permitted development, within size limits.
Which type of loft conversion suits homes in Slough?
Rear dormers for terraced houses. Semi-detached houses are the most common type here (29.5% of households), and most homes were built between 1945 and 1972. A specialist survey will confirm what your roof allows.
Does a loft conversion add value in Slough?
It can. The median semi-detached house in the Slough area sold for £478,000 in 2025. Nationwide's 2023 research suggests adding a bedroom adds about 11% for this type of house, and a bedroom with a bathroom as much as 25%. On that median, that is roughly £53,000 to £119,000. This is a rough guide from national research, not a valuation.
Sources
- ONS LSOA (2021) to Built-up Area (2022) best-fit lookup (2022-12-31)
- Census 2021, TS044 Accommodation type (households), ONS via Nomis (2021-03-21)
- Census 2021, TS052 Occupancy rating for bedrooms, ONS via Nomis (2021-03-21)
- Census 2021, TS061 Method used to travel to work, ONS via Nomis (2021-03-21)
- VOA Council Tax: stock of properties 2025, CTSOP3.1 (property type, LSOA) (2025-03-31)
- VOA Council Tax: stock of properties 2025, CTSOP4.1 (build period, LSOA) (2025-03-31)
- HM Land Registry Price Paid Data (standard sales only) (2026-09-22)
- Nationwide, "Bedrooms, bathrooms and extensions: what adds value to your home in 2023?" (2023)
- Slough Borough Council building control charges (2019-09-01)
- Slough Borough Council conservation areas
- Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 1, Class B
Last reviewed 22 September 2026. The figures on this page come from public datasets and published guides. We update them as new data is released.
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