Loft Conversion Cost UK
Estimates based on UK trade benchmark data, updated 25 April 2026. Methodology →
A loft conversion — sometimes called an attic conversion or loft extension — is one of the most effective ways to add living space and value to your home without extending the footprint. Whether you're considering a simple Velux conversion or a full dormer, costs vary significantly based on the type of conversion, your roof structure, and location. This guide covers everything you need to budget effectively.
Most projects fall between £54,000 and £84,000. Budget refreshes start near £24,000; premium projects reach up to £168,000.
Typical UK Cost by Scenario
Typical timeline: 4 to 10 weeksBudget
£31,200
typical figure
- Rooflights
- Insulation
- Plaster
Mid-range
Most common£69,000
typical figure
- Balanced specification
- Practical sanitaryware
- New storage joinery
Premium
£135,000
typical figure
- Premium bathroom fit-out
- Bespoke wardrobes
- Upgraded roof structure
Figures are typical UK averages including labour, materials, and VAT at 20% for standard-rated work.
Save money on your quote
Already got a quote from a builder?
Upload it and our AI Quote Checker flags overcharges, missing scope, and the questions worth asking — in about a minute.
Typical UK Cost Ranges for Loft Conversion
| Item | Cost Range |
|---|---|
| Velux / rooflight conversion | £18,000 – £36,000 |
| Dormer loft conversion | £30,000 – £60,000 |
| Hip-to-gable conversion | £36,000 – £72,000 |
| Mansard conversion | £48,000 – £84,000 |
| Staircase installation | £2,400 – £6,000 |
| En-suite in loft | £3,600 – £9,600 |
All prices are approximate UK averages including labour, materials, and VAT at 20% (2026). Some qualifying renovations for empty homes may use the reduced 5% VAT rate.
Real UK Cost Examples
- Budget scenario (Velux loft conversion, 2-bed terrace, Yorkshire): Rooflights, insulation, plaster, electrics and a simple staircase. Not done: dormer, en-suite or major roof restructuring. Approx cost: £20,000 to £32,000.
- Mid-range scenario (rear dormer with bedroom and shower room, 3-bed semi, Manchester): Balanced specification, practical sanitaryware, new storage joinery and full compliance upgrades. Approx cost: £45,000 to £70,000.
- High-end scenario (L-shaped dormer in a period property, London): Premium bathroom fit-out, bespoke wardrobes, upgraded roof structure and full fire-compliance package. Main cost drivers: structural complexity, access and finish level. Approx cost: £85,000 to £140,000.
Related next steps:
What You Can Get For Your Budget
- Around £30,000: straightforward Velux conversion focused on one extra room and basic finishes.
- Around £60,000: dormer conversion with much better usable space and potential for a compact bathroom.
- £100,000+: complex lofts with premium joinery, bathroom quality, stronger structural intervention and architectural detailing.
Hidden Costs to Watch For
- Staircase geometry constraints can trigger extra design and structural revisions.
- Fire door, alarm and escape upgrades on lower floors are often overlooked early.
- Roof strengthening and steel requirements vary more than homeowners expect.
- Scaffolding duration extensions can add cost if programme slips.
Related next steps:
Should You Do This Renovation?
- Worth it in many urban homes where footprint expansion is limited but roof volume is usable.
- Not worth forcing when head height and staircase constraints create compromised room quality.
- Lofts can add strong value when they create a true extra bedroom and compliant bathroom, not just occasional space.
Common Cost Mistakes
- Assuming all loft types cost similar regardless of roof shape and access.
- Underbudgeting for full compliance upgrades beyond the loft itself.
- Changing dormer size or window package mid-design.
- Picking on price without checking structural engineer coordination and sequencing.
Key Cost Factors
- Type of conversion — Velux is cheapest; mansard is most expensive.
- Roof structure — trussed roofs require more structural work than traditional rafters.
- Planning permission — dormers at the rear under permitted development; front and mansard usually need planning.
- Party wall agreements — required for terraced and semi-detached properties.
- Staircase location — affects the layout and usable space on the floor below.
- Building regulations — fire safety, insulation, and structural calculations are mandatory.
- Services — electrics, plumbing (if adding en-suite), and heating.
Dormer vs Velux Cost Comparison
- Velux-only loft conversions are usually cheaper where head height is already adequate.
- Dormer conversions increase usable floor area and resale utility but add structural and weatherproofing cost.
- Stair positioning and fire-compliance upgrades often decide final affordability more than window choice alone.
Typical Timeline
| Item | Duration |
|---|---|
| Velux / rooflight conversion | 3 to 5 weeks |
| Dormer conversion | 5 to 8 weeks |
| Mansard conversion | 8 to 12 weeks |
Regional Cost Variations
Loft conversions in London typically cost 20–40% more than national averages due to higher labour rates and the prevalence of Victorian terraces requiring party wall agreements. Northern England and Scotland tend to be more affordable.
Costs in your area
Compare regional benchmarks for loft conversion using the same UK baseline assumptions.
Ways to Reduce Costs
- Choose a Velux conversion if you don't need maximum headroom.
- Get at least three detailed quotes and compare scope, not just price.
- Do finishing work (painting, flooring) yourself after the structural work is complete.
- Avoid moving the staircase if possible to reduce structural changes.
- Consider pre-fabricated dormers which can reduce on-site build time.
Want a personalised estimate?
Use the Renovation Cost Calculator to estimate costs based on your property size, location, and project scope.
Try the Renovation Cost Calculator