What is a hip-to-gable loft conversion?

A hip-to-gable loft conversion replaces the sloping side (the hip) of a semi-detached or detached roof with a vertical gable wall. This extends the ridge and creates enough space for a staircase and a full-size room, usually combined with a rear dormer.
How much does a hip-to-gable loft conversion cost in Brentwood?
In Brentwood, a hip-to-gable loft conversion typically costs £58,500–£82,500 for a hip-to-gable with rear dormer, including VAT at 20% (standard rate). The guide for Brentwood reflects typical costs in the East of England, roughly 6% above the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A hip-to-gable with rear dormer | £58,500–£82,500 |
| Higher specification | £82,500–£103,000 |
The biggest cost drivers are:
- Gable wall construction and finish
- Bathroom and plumbing
- Roof tile matching
- Size of the rear dormer
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a hip-to-gable loft conversion in Brentwood?
Before anything is built in Brentwood, we confirm which approvals apply in England. In England a hip-to-gable conversion is often permitted development within the 50 cubic metre roof volume limit for semi-detached and detached houses, provided the gable does not face a road and the house is not in a conservation area.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
We check this for your address before design work starts, so there are no surprises later.
What we handle
On a typical hip-to-gable loft conversion we handle:
- Insulation, electrics, plumbing and plastering
- Staircase and fire-safe escape route
- Drawings and structural calculations
- Roof extension and rear dormer
- Steel beams and floor joists
- Survey and planning check
How long does it take?
Build time is typically 7 to 10 weeks on site. Design and approvals come first and typically take 6 to 12 weeks, depending on the approval route.
Building in Brentwood
Many towns in the East of England have estates built since the 1970s, where garage conversions and rear extensions are popular.
We work across Brentwood and neighbouring areas such as Billericay, Upminster and Hornchurch. Postcodes we cover in Brentwood include CM14.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about hip-to-gable loft conversions in Brentwood
Will I need building regulations approval?
Yes. All loft conversions to habitable rooms need building control approval for structure, fire safety, insulation and stairs.
Can the gable be brick?
Yes. We match the existing finish, whether brick, render or pebbledash.
Is a hip-to-gable conversion permitted development?
Often yes in England, within the 50 cubic metre roof volume limit for semi-detached and detached houses. It is not permitted development in conservation areas or where rights have been removed.
Do you build hip-to-gable loft conversions in Brentwood?
Yes. We build hip-to-gable loft conversions across Brentwood, including postcodes CM14. Every project starts with a free home visit.
How much does a hip-to-gable loft conversion cost in Brentwood?
In Brentwood, a hip-to-gable loft conversion typically costs £58,500–£82,500 for a hip-to-gable with rear dormer, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
