Loft Conversion Types

Rooflights are cut into the existing roof slope and nothing else about the roof changes. It is the cheapest and quickest conversion, and because the profile stays as it is, planning permission is rarely a question.

• Needs 2.2m from the joists to the underside of the ridge — 2.4m on modern trusses
• You keep the sloping eaves, so usable floor area is roughly half a dormer’s
• Almost always permitted development, even in most conservation areas

A flat-roof box built out across the rear slope. It gives more usable floor area than any other single-elevation option, with straight walls and full standing height where a rooflight room would have eaves.

• The default choice for a mid-terrace, which has no hip to square off
• Must sit 200mm back from the original eaves and stay under the existing ridge
• Party wall notices needed where it meets a shared wall — two months’ notice

The sloping side of the roof is built up into a vertical gable wall. Its real value is often structural rather than spatial: squaring off the hip is what creates the headroom a compliant staircase and landing need.

• Only for houses with a hipped roof — semis, detached and most end-terraces
• New gable must match the original in brick, render, tile or slate
• Frequently paired with a rear dormer, which makes it a wrap around

A dormer inserted into the hipped end rather than the rear slope. You gain less floor area than a full gable but the roof keeps its original shape — which matters on a matched pair or inside a conservation area.

• Cheeks finished in hanging tiles matched to the roof, not render
• The option when the rear slope is short, overlooked or already used
• Permission normally required where the hipped end faces a highway

A hip-to-gable and a rear dormer built as one, wrapping the new floor around the corner. It is the largest conversion available and the only one that regularly delivers a genuine second floor rather than one big room.

• Around 40–46 m² — comfortably two bedrooms and a bathroom
• Usually consumes the whole 50m³ allowance, so planning is more likely
• Six weeks on site, and the most technical build of the six

The existing roof is removed and rebuilt higher or at a steeper pitch, creating headroom where there was none. It is the answer for bungalows, chalets and shallow-pitch houses that cannot otherwise be converted.

• Needs full planning permission — raising the ridge is never permitted development
• A temporary weatherproof scaffold roof covers the house throughout
• Always priced against a ceiling drop first, which is often the cheaper fix