Loft Conversions in Trowbridge.

§ Overview

A bedroom, office or annex — without losing garden.

For most homes in Wiltshire and Somerset, a loft conversion is the cheapest pound-per-square-metre way to add real, usable space. No deeper foundations, no garden lost, often no planning permission. Done well, it adds 15–20% to the value of the house.

We've completed every conversion type, from a £24k Velux job in a Trowbridge bungalow to a £95k mansard in a Georgian terrace in Bath. The four mainstream options:

Velux / roof-light conversion

The simplest and cheapest. Roof shape stays as-is; we add Velux roof windows, insulate, board out, install a staircase and run electrics. Best for properties that already have generous head height and don't need extra floor footprint. Often permitted development.

Dormer conversion

The most popular choice. A box-shaped extension built out from the rear roof slope — gives full standing height, a flat ceiling, and a much larger floor area. Looks like a proper room, not a sloped attic. Almost always PD on the rear, often visible only from the back garden.

Hip-to-gable conversion

For end-of-terrace, semi-detached and detached houses with a sloped "hip" end. We replace the slope with a vertical gable wall, which adds floor area at the gable end. Often combined with a rear dormer for maximum space.

Mansard conversion

The biggest transformation — almost a full-storey rebuild of the roof at a steeper angle (typically 70°). Maximum head height across the whole footprint, biggest planning challenge, and usually most expensive. The right choice for terraced houses where dormer/hip options aren't available.

Have I got enough head height?

The single biggest feasibility check. Stand in your loft and measure from the top of the joist to the underside of the ridge:

• 2.4m or more — comfortable Velux or dormer conversion possible.
• 2.2m–2.4m — Velux marginal, dormer recommended.
• 2.0m–2.2m — usually only viable as a dormer or with a roof raise.
• Under 2.0m — needs roof modification or isn't worth doing.

The other constraint is the existing staircase: building regs require continuous protected escape from the new loft to the front door. Sometimes that means a small reconfiguration of the floor below.

Planning & building regs.

Loft conversions are heavily regulated for fire safety and structural reasons. The big rules:

• Permitted development volume limit: 40m³ for terraced houses, 50m³ for semi/detached. Mansards always need planning.
• Conservation areas & listed buildings: PD rights removed; full planning and (if listed) Listed Building Consent required. Common in central Bath, Bradford-on-Avon, Frome.
• Fire escape: Protected staircase down to a final exit. Fire doors on every floor opening onto the stair. Linked smoke alarms.
• Structural calcs: Existing ceiling joists are not strong enough to be a floor — we install new floor joists alongside, with structural-engineer calcs.
• Insulation: Roof needs to meet current U-values (typically 0.16 W/m²K) — usually means thick PIR board between & under rafters.
• Party wall (terraced/semi): Notice required to neighbours; works to the shared wall need their consent.

Recent loft conversions.

FAQs.