Double Storey Extensions — Windsor SL4
Double Storey Extension in Windsor — Kitchen Below, Master Bedroom Above
Location
Windsor, SL4
Project Type
Double Storey Extensions
Duration
19 weeks on site
Scope
Full two-storey side extension, planning, structural, full first fix both floors
The Brief
A 1950s detached property in a residential road in Windsor, SL4. The side of the property had a narrow attached garage that the clients used for bikes and clutter. The brief was to demolish the garage and replace it with a proper two-storey extension — a kitchen extension on the ground floor expanding into the old garage footprint, and a new master bedroom with en suite on the first floor above.
Our Approach
A double storey extension of this size required full planning permission from RBWM. The application was prepared by a local architect, and we worked alongside them on the structural approach. RBWM approved the application with minor conditions (matching brick, obscure glazing to the side first-floor window). Building regulation drawings followed, covering the enhanced strip foundations for two-storey loading, the first floor structure, the roof tie-in to the existing hipped roof, and full U-value calculations for all new walls, floor, and roof.
The Build
Existing garage demolished and arisings removed. Excavation to 1.4m for strip foundations under two-storey load. 350mm wide x 300mm deep concrete strip, stepped to suit the sloping site. Ground floor cavity brickwork to match existing 1950s buff brick. First floor steelwork: a 254x146 UC beam at first floor level to carry the upper floor joists across the span. 200mm C24 floor joists installed. First floor brickwork to eaves. New hipped roof structure designed and built to tie into the existing roof without disturbing the original covering — only the valley between old and new was opened. Pitched concrete tile to match existing Redland 49. Full cavity insulation to all new walls. First fix electrics on both floors. En suite first-fix plumbing (waste runs, water supply) on first floor.
Materials & Specification
Facing brick: Ibstock Cheshire Weathered Buff to match 1950s original. Inner block: Thermalite Shield 3.6N. First floor beam: 254x146 UC section. Floor joists: 200mm C24 at 400mm. Roof tile: Redland 49 Concrete in Farmhouse Red. Insulation: Knauf Dritherm 37 full-fill.
The Result
The completed double storey extension added 22 square metres on the ground floor (new kitchen) and 20 square metres on the first floor (master bedroom and en suite shell). The brick matching was approved by the client as near-identical to the existing house. The planning condition for obscure glazing to the side window was discharged by RBWM following submission of the product specification.
Project Photos
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Photos from this project will be added shortly. View our project gallery for completed work examples.
Project FAQs
Did this need planning permission?
Yes. A double storey side extension of this scale required full planning permission from RBWM. The application took approximately 10 weeks to determine. Planning was approved with minor conditions around brick matching and glazing specification.
How much does a double storey extension cost?
This project was completed at £87,000 including planning support, all structural works, groundworks, brickwork, roofing, insulation, plastering, and first fix on both floors. Bathrooms, kitchen, and second fix were completed separately.
Can you match original 1950s brick?
Yes — brick matching is something we do on every project where the extension adjoins existing masonry. We assess the existing brick at the initial visit and source the closest available facing brick, using reclaimed bricks where a perfect match is critical.
Why Choose Berkshire Bespoke Builders
- ✓Owner-managed — Pind Sahota is on site and managing your job personally
- ✓32 years on the tools — time-served builder, 25 years fitting bespoke kitchens
- ✓Fully insured — public liability and employer's liability on every project
- ✓Fixed-price written quotes — itemised by material and labour, no hidden extras
- ✓Building regs managed — we submit applications and attend all inspection stages
- ✓Based in Berkshire — Binfield, Bracknell RG42. No travel surcharges or delays
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