As families grow, the need for an extra bedroom becomes paramount. Whether you are adding a master suite with a walk-in wardrobe, a nursery, or a guest room, extending your home to add a bedroom is a highly practical investment that increases your property's resale value and appeal.
Unlike kitchen or bathroom extensions, bedroom extensions are generally less complex and more cost-effective because they do not require heavy plumbing or gas lines (unless you add an en-suite). In this 2026 cost guide, we break down single vs. two-storey bedroom extension costs, en-suite additions, and finishes.
Average bedroom extension costs
On average, constructing a bedroom extension in the UK costs between £1,200 and £3,300 per square metre depending on location and quality of finishes. The total price is determined by whether the bedroom is a ground-floor extension or part of a new two-storey structure.
Typical cost estimates for bedroom extensions (excluding VAT):
| Project Type | Size (m²) | Average Build Cost |
|---|---|---|
| Small Bedroom Extension (Single-Storey) | 10 m² | £12,000 - £25,000 |
| Medium Bedroom (Single-Storey) | 20 m² | £24,000 - £48,000 |
| Master Suite with Ensuite (Double-Storey) | 35 m² | £55,000 - £95,000+ |
Single-storey vs. double-storey bedroom extensions
- Single-Storey Bedroom Extension (£16,000 - £67,000): Typically built on the ground floor. It can serve as a ground-floor master suite, an annex for elderly relatives, or a playroom. Often falls under Permitted Development rights.
- Two-Storey Bedroom Extension (£24,000 - £100,500+): Involves building over an existing ground-floor structure (like a garage or kitchen) or building a new two-storey extension. Although the total cost is higher, it is more cost-effective as it doubles your layout area without taking up additional garden footprint.
Fit-out details: En-suites and fitted wardrobes
To make a new bedroom truly functional, most homeowners add storage and bathing facilities:
- Adding an En-suite (£3,000 - £10,000): Plumbing, venting, and tiling a small shower room adds comfort. Costs vary based on whether waste pipes can easily connect to your existing soil stack.
- Bespoke Fitted Wardrobes (£2,500 - £6,000): Custom joinery makes the best use of sloping ceilings and alcoves. A professional joiner day rate is typically £200 to £320 per day.
- Decorating and Flooring (£800 - £2,500): Plastering, painting, and laying carpet or engineered oak flooring. Carpet fitting typically costs £25 to £45 per m² (supply and fit).
Structural requirements and permissions
- Building Regulations: Mandatory for all conversions. Structural insulation must meet strict thermal performance requirements (U-values) to ensure the bedroom is warm and energy-efficient.
- Planning Permission: If the extension is at the front of the property, exceeds height limits, or is in a conservation area, you will need to submit plans to your local council.
Connect with vetted builders on GetBuilder
A bedroom extension requires skilled carpentry, masonry, and insulation installation. To find a vetted local builder, follow these simple steps:
- Post your project: State your desired room size, en-suite details, and location for free on GetBuilder.
- Compare transparent quotes: Check if quotes separate structural materials, window installation, insulation, and interior joinery.
- View portfolios and reviews: Review checked ratings and photographs of previous extensions before hiring with confidence.
