# Loft Conversion Costs & Types: The 2026 Guide

> The four main loft conversion types, what each costs in 2026, and which suits your roof — plus when you need planning permission.

Source: https://renomate.co.uk/blog/loft-conversion-cost-types

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# Loft Conversion Costs & Types: The 2026 Guide

8 April 2026 · 6 min read

The four main loft conversion types, what each costs in 2026, and which suits your roof — plus when you need planning permission.

## What a loft conversion costs

**Most loft conversions cost between £25,000 and £60,000 in 2026.** A simple rooflight (Velux) conversion is cheapest at around £25,000–£40,000; a dormer runs £35,000–£55,000; and a hip-to-gable or mansard — which change the roof shape for more space — sit at £45,000–£75,000+.

## The four main types

A **rooflight** conversion adds windows without changing the roofline (cheapest, but you keep the existing headroom). A **dormer** adds a box that increases floor space and headroom. A **hip-to-gable** extends a sloping side wall upward, and a **mansard** rebuilds the roof for the most space — the priciest option.

## Will my loft convert?

The key is headroom: you generally need around 2.2–2.4m from floor to ridge. Roof structure matters too — older “cut” roofs are easier than modern trussed roofs, which need reinforcing. A specialist can tell you in a single visit.

## Do I need planning permission?

Many loft conversions fall under permitted development, but front dormers, work in conservation areas, and anything over the volume limits need permission. All loft conversions need [building regulations](https://renomate.co.uk/renovations/loft-conversions) sign-off, especially for the staircase and fire escape.

## Get a quote for your loft

The cheapest room you’ll ever add is the one you already have. [Tell us about your loft](https://renomate.co.uk/enquire) and we’ll match you with a vetted local conversion specialist.

## Frequently asked questions

### How long does a loft conversion take?

Most take **6–10 weeks** on site. A dormer or mansard takes longer than a simple rooflight conversion.

### Do I need stairs to my loft?

Yes — building regulations require a proper fixed staircase (not a ladder) for a habitable loft room, plus fire-safety measures such as fire doors on the floors below.

### Does a loft conversion add value?

Adding a bedroom, ideally with an ensuite, is one of the most reliable ways to add value — often returning a large share of the cost, particularly where floor space is at a premium.

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