- Site visit and measurements
- Plan review and feasibility assessment
- Fixed-price quotation delivered
Premium Home Extensions | Hampshire, Surrey & Dorset
Why Choose Crown for Your Extension?
Working towards
ISO 9001
Standards
Types of Extensions We Build
Single-Storey Rear Extensions
Double-Storey Extensions
Wrap-Around Extensions
Used and loved by people at leading companies
Why Extensions Go Wrong (And How Crown Prevents It)

1: Poor Ground Conditions
Many builders quote without surveying ground conditions. When they hit clay, rock, or high water tables, you face unexpected foundation costs.

2: Building Control Rejections
Rushed submissions lead to rejected applications, causing delays and redesign costs.

3: Structural Engineer Delays
Waiting for structural calculations mid-project brings construction to a halt.

4: Poor Trade Coordination
Electricians arriving before plastering is done. Plumbers waiting for floor screed to cure. Poor scheduling creates delays and frustration.
Premium Finishes with Cladco
Benefits
- 25-year warranty on composite cladding
- Weather-resistant and colour-stable
- Wide range of colours and textures
- Sustainable and recyclable materials
Visit cladco.co.uk to explore finish options.
Your Extension Timeline
- Structural engineer engagement
- Building Control consultation
- Materials ordering
- Groundwork and drainage
- Foundation pour and curing
- Building Control inspection
- Brickwork and blockwork
- Steelwork installation
- Roof structure
- Roofing and flashing
- Windows and doors
- External finishes
- Electrical wiring
- Plumbing and heating
- Insulation
- Plastering
- Kitchen and bathroom fitting
- Decoration and snagging
- Building Control sign-off
Step-by-Step Process
Get in touch with us via phone or email to discuss your project.
We provide an initial quotation based on available drawings and specifications.
We arrange a site visit to assess the property and discuss the project in detail, answering any questions you may have.
Once final plans, calculations, and Building Regulations approval are confirmed, we finalise your quotation.
FAQ Questions
Frequently Asked Questions
Many single-storey rear extensions fall under Permitted Development and don't require
planning permission. However, this depends on your property type, location (conservation
area?), and how much you've already extended. We'll advise during your initial assessment
and handle any planning applications required.
Extension costs vary significantly based on size, complexity, and specification. As a rough
guide: single-storey extensions typically cost £2,000-£2,500 per square metre; double-storeys
£1,800-£2,200 per square metre (better value due to shared foundations and roof). We
provide detailed fixed-price quotations after our site assessment.
Typical timelines: single-storey (10-14 weeks), double-storey (14-18 weeks), side return (8-
12 weeks). These timelines assume planning is already approved and include a 2-week preconstruction planning period.
Usually not. We maintain access to your home throughout and take dust and noise control
seriously. For larger projects affecting kitchens or bathrooms, we'll discuss temporary
arrangements during our planning phase.
If your extension is built on or near a boundary with neighbours, you may need a Party Wall
Agreement. We can recommend specialist Party Wall surveyors and coordinate the process
on your behalf.
