Loft Conversion Cost: Complete Breakdown 2026 in Ferndown
A loft conversion is one of the best-value home improvements — it adds a bedroom and bathroom without losing garden space. Costs range from £30,000 for a simple Velux conversion to £90,000 for a full mansard, depending on the type and specification. Here is what Ferndown homeowners should expect to pay.
Local cost range — Ferndown
£40,000–£70,000
What affects costs in Ferndown
Ferndown's bungalows are particularly suited to dormer and hip-to-gable conversions, effectively adding a full upper floor at a fraction of the cost of building upwards.
Cost estimator
Rates for Ferndown
6m × 4m = 24m²
Estimated cost in Ferndown
Excl. VAT (£9821 – £14168)
Local insight: Ferndown's generous plot sizes and good access make it one of the most straightforward (and cost-effective) areas to extend in Dorset. Bungalow conversions are particularly popular here.
Cost breakdown
Cost by conversion type
Velux/rooflight: £30,000–£45,000 (simplest, no structural roof changes). Rear dormer: £40,000–£60,000 (most popular, adds headroom). L-shaped dormer: £50,000–£70,000 (two dormers meeting at a corner). Hip-to-gable + dormer: £55,000–£75,000 (maximises space on hipped roofs). Mansard: £65,000–£90,000 (most complex, most space).
What drives the cost
The main cost factors are: (1) type of conversion (dormer/mansard cost more than Velux); (2) size (one room or two); (3) en-suite bathroom (adds £5,000–£10,000); (4) staircase complexity (over the existing stair is cheapest); (5) access difficulty (scaffolding costs vary).
Professional fees for loft conversions
Design: £250 (PlanBuildCo). Structural calculations: £350 (always needed for floor joists and any roof steels). Planning application: £2,200 + £258 if required. Building Regulations: £399. Building control: £400–£800. Total professional fees: £1,500–£4,000.
| Type | Build Cost | Estimated Total |
|---|---|---|
| Velux/rooflight | £30,000–£45,000 | £35,000–£55,000 |
| Rear dormer | £40,000–£60,000 | £48,000–£72,000 |
| L-shaped dormer | £50,000–£70,000 | £58,000–£82,000 |
| Hip-to-gable + dormer | £55,000–£75,000 | £63,000–£88,000 |
| Mansard | £65,000–£90,000 | £75,000–£105,000 |
National guide figures. Local rates in Ferndown: £40,000–£70,000.
Frequently asked questions
National guide
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