Hip to gable loft conversions

What is a hip to gable loft conversion?

On a hipped roof, the end of the roof slopes down as well as the front and back, which leaves a small, awkward loft. A hip-to-gable conversion builds the end wall up to the ridge and extends the roof across it, so the loft becomes a much larger, more regular space.

It involves bigger structural changes than a dormer, including new masonry, roofing and often steelwork, which is why it usually costs more.

Which houses suit it

Hip-to-gable conversions are common on semi-detached and end-of-terrace houses, and on detached houses with one or both ends hipped. A mid-terrace house has no hipped end, so it is not an option there.

How much does a hip to gable loft conversion cost?

In Berkshire, expect roughly £57,000 to £91,000 to build a typical 30m² hip to gable conversion, before VAT and fees. Elsewhere in the UK the typical range is £50,000 to £70,000. These are research-based estimates, not quotes.

Add VAT, drawings, a structural engineer, building control and any party wall costs to get a total. Use the calculator for your own size and finish, or read the cost guide.

Planning and building regulations

The permitted development rules allow for hip-to-gable enlargements: they are exempt from the rule about keeping the eaves, but must stay within the volume limits (50m³ for a semi-detached or detached house), sit no higher than the existing roof and use similar materials. Combined with a rear dormer, the whole enlargement counts towards the volume.

You need planning permission in a conservation area, where an Article 4 direction applies, or if the design goes beyond the limits.

Whatever the planning position, every loft conversion needs building regulations approval, covering structure, fire safety, stairs and insulation. See our planning guide and building regulations guide.

Pros and cons

Pros

• Turns a small hipped loft into a large room
• Often combined with a rear dormer for even more space
• Can be permitted development

Cons

• Costs more than a dormer, because of the structural work
• Only works on houses with a hipped end
• Changes the look of the house from the side

How long it takes

Checkatrade's typical build time for a hip to gable conversion is 10 to 14 weeks on site, after design, approvals and any party wall process. See the process and timeline guide.

This may be allowed under permitted development or may need planning permission, depending on the size and your property.

Where it's common in Berkshire

Based on the local mix of homes, this type is most likely to suit houses in Ascot, Maidenhead, Newbury, Twyford and Wokingham:

• Ascot: 67.1% of households in semi-detached or detached houses
• Maidenhead: 57.1% of households in semi-detached or detached houses
• Newbury: 54.3% of households in semi-detached or detached houses
• Twyford: 73.1% of households in semi-detached or detached houses
• Wokingham: 69.1% of households in semi-detached or detached houses

From 2021 Census and VOA figures for each town. A tendency, not a guarantee for any one house.