A loft conversion is consistently one of the best-value home improvements you can make in Somerset. You are adding usable space — typically a bedroom and bathroom — without increasing your footprint. Based on what we have built across Somerset, Devon and Dorset, loft conversions typically add 15–25% to a property's value while costing considerably less than moving house.
Types of Loft Conversion Available in Somerset
- Velux (roof light) conversion — the most affordable option. Skylights are added but the roof shape does not change. Requires a minimum head height of 2.2m at the ridge
- Dormer conversion — a box-shaped extension to the roof slope adds significant floor area and headroom. The most popular choice in Somerset
- Hip-to-gable — converts a hipped roof end to a gable, increasing floor area. Common on 1930s–1960s semi-detached houses
- Mansard — changes the entire roof structure. Maximum space but highest cost. More common on terraced Victorian properties
- L-shaped dormer — a dormer that wraps around a rear extension roof. Great for maximising space on Victorian terraces
2026 Loft Conversion Cost Guide — Somerset
| Conversion Type | Typical Floor Area Added | Price Range |
|---|---|---|
| Velux / roof light only | 10–20m² | £22,000 – £35,000 |
| Single dormer (rear) | 15–25m² | £35,000 – £52,000 |
| Double dormer (rear) | 20–35m² | £45,000 – £65,000 |
| Hip-to-gable | 20–30m² | £42,000 – £62,000 |
| Hip-to-gable + rear dormer | 30–45m² | £55,000 – £80,000 |
| Mansard | 30–50m² | £65,000 – £95,000 |
| L-shaped dormer | 30–50m² | £58,000 – £85,000 |
Note:Prices above include structural works, roof alterations, floor joists, insulation, staircase, one bedroom, one en-suite bathroom, fire doors, and electrics. Kitchen and bedroom furniture are excluded. VAT at 20% is not included in these figures.
Does a Loft Conversion Need Planning Permission in Somerset?
Most loft conversions in Somerset are Permitted Development — meaning no planning application is needed. The key rules are:
- The total volume added must not exceed 40m³ (terraced house) or 50m³ (detached or semi)
- No part of the conversion can extend beyond the plane of the existing roof slope on the principal elevation (front of house)
- The conversion must not be higher than the existing ridge
- Rooflights must be obscure glazed if within 1.7m of the external wall on a side elevation
- Conservation areas, AONBs and listed buildings always require planning consent
Is My Loft Suitable for Conversion?
Not every loft in Somerset can be converted. Before getting quotes, check:
- Head height — you need at least 2.2m from the floor to the ridge for a habitable room
- Roof structure — modern trussed roofs (common in post-1965 houses) can be converted but require more structural work than traditional cut roofs
- Water tank — a tank in the loft needs to be relocated. Budget £500–£1,500
- Staircase access — a new staircase needs to fit within the existing floor plan. This is the most common constraint we encounter
- Purlins and chimney stacks — these can reduce usable floor area
As part of a free site visit we will check all of the above and tell you honestly whether your loft is suitable, what type of conversion is possible, and give you a realistic cost estimate.
Book a free loft conversion assessment
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