Single Storey Rear Extension in Bracknell — 1970s Semi to Open-Plan Living
A 1970s semi-detached property in Bracknell RG12. Standard post-war layout — small separate kitchen at the rear, small separate lounge at the front. The clients wanted a larger, open kitchen-dining room and a better connection to the garden. We built a single storey rear extension with GRP flat roof, two Velux fixed rooflights, and sliding patio doors. The extension, combined with removing the internal wall, created an open-plan kitchen-diner-family room that transformed how the family uses their home. Eleven weeks.
Project Summary
- Location
- Bracknell, RG12
- Property type
- Semi-detached, 1970s
- Service
- Single Storey Extension
- Extension type
- Single storey rear
- Build duration
- 11 weeks on site
- Roof type
- GRP flat roof
- Rooflights
- 2× Velux fixed rooflights
- Glazing
- Sliding patio doors
- Building regulations
- Approved, Bracknell Forest BC
Build Documentation
From Groundworks to Completion
Stage 1
Foundations
Bracknell clay soil required careful attention. Foundations at 750mm depth, below the zone of seasonal clay movement. Strip foundation in concrete, inspection by Bracknell Forest Building Control before concrete pour.
Stage 2
Roof with Velux Rooflights
Flat roof joists and OSB deck built at 2.5m height. Two Velux GGL-style fixed rooflights set into the deck before GRP membrane. The rooflights are the primary source of daylight — the rear garden aspect is south-facing, so the roof lights deliver direct sunlight into the kitchen from midday onwards.
Stage 3 — Completed
Internal Works
Internal wall between old kitchen and new extension removed. Structural opening created under temporary propping, RSJ lifted into padstones. Plaster skim, floor screed, first-fix electrics and plumbing before handover.
The Brief
The brief was simple: more space in the kitchen, more light, and a door to the garden. The existing 1970s kitchen was 3m × 2.5m — a tight, galley-format room. The clients wanted enough room for a kitchen island, a dining table, and a comfortable seating corner. The extension delivered all three.
What We Built
Single storey rear extension, 4m × 3.5m footprint. Standard cavity brick and block construction — existing house stock brick tone matched for the extension outer leaf. GRP flat roof with 150mm PIR insulation, two fixed Velux rooflights (0.6m × 0.9m each) positioned over the new dining zone. Sliding patio doors (2.4m wide × 2.1m high) in the rear elevation. RSJ spanning the internal opening from existing kitchen to new extension — 203×133 UC calculated for 3.2m span. Foundation depth 750mm to meet Bracknell clay soil conditions.
Why Berkshire Bespoke Builders
- ✓Owner-managed — Pindi on site, personally
- ✓32 years experience — time-served builder
- ✓Fixed-price quotes — itemised, written, no extras
- ✓Building regs managed — submissions + inspections
- ✓Based in Berkshire — Binfield, RG42
FAQ
Single Storey Extensions Questions Answered
Why are Bracknell foundations often deeper than elsewhere?
Parts of Bracknell sit on London Clay subsoil. Clay soil expands when wet and contracts in dry conditions. Building regulations require foundations to be deep enough to be below this active zone — typically 750mm to 900mm on clay sites, compared to 600mm on sand or gravel. We check subsoil conditions at every site visit.
What is a GRP flat roof and how long does it last?
GRP (glass reinforced polyester) is a fibreglass membrane applied as a liquid, curing to a rigid surface. A properly installed GRP flat roof carries a 25-year product warranty and typically lasts 40+ years with no maintenance beyond keeping outlets clear.
Do rooflights require planning permission?
Fixed rooflights that sit flush or near-flush with the roof surface are generally permitted development. The two Velux rooflights on this project required no planning permission. Raised kerb rooflights sometimes require permitted development assessment — we check this at the design stage.
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