Full-Width Rear Dormers in Greater London
From the first measured survey to the completion certificate, we run full-width rear dormers projects in Greater London as a single, managed piece of work.
Full-Width Rear Dormers — indicative geometry
Full-Width Rear Dormers for Greater London homes
Greater London is a mix of Victorian and Edwardian terraces with rear outriggers, plus large stretches of 1930s semi-detached suburbs, and each of those wants a different dormer form — which is why we survey before quoting rather than pricing off a photograph.
A full-width rear dormer runs from party wall to party wall, squaring off the entire rear slope. On a standard terrace or semi it typically converts 12–18m² of crawl space into full-height room — enough for a double bedroom and an en-suite. Set back 200mm from the eaves and 500mm below the ridge, it usually falls inside permitted development on a house that has not been extended before.
Key specification
| Typical projection | 4.0m – 8.0m wide |
|---|---|
| Set-back | 200mm from eaves, 500mm below ridge |
| Structure | Steel ridge beam plus floor steels |
| Roof finish | GRP, EPDM or single-ply membrane |
Planning and building control in Greater London
We run the permitted development test on your specific property: set-back from the eaves, height against the ridge, volume allowance and whether an Article 4 direction applies locally.
Building regulations approval is separate and always required. We submit the application, book the inspections around the programme and hand you the completion certificate at the end — the document a buyer's surveyor will ask to see.
Why homeowners in Greater London use us
We only do dormers. That sounds like a limitation until you have watched a general builder improvise a back gutter on a wet Thursday.
The quickest route is a photograph of the rear elevation over WhatsApp — we can usually tell you what is feasible before anyone visits.
Other dormer work in Greater London
- Timber Dormer Windows in Greater London
- Conservation Dormer Windows in Greater London
- Lead & Zinc Dormer Roofing in Greater London
- Pitched Roof Dormers in Greater London
- Shed Dormers in Greater London
- Eyebrow Dormers in Greater London
- Bungalow Dormer Conversions in Greater London
- Dormer Window Replacement in Greater London
FAQs
Full-Width Rear Dormers in Greater London — FAQs
Do you handle the planning application?
Yes. We prepare measured drawings, elevations and sections, submit the application or the lawful development certificate, and deal with the case officer's queries. On conservation and listed work we also put together the heritage justification the application needs.
What is the difference between a dormer and a Velux?
A rooflight sits flush in the roof slope and gives you light without any extra height — you still have a sloping ceiling. A dormer projects out from the roof and creates vertical walls with a level ceiling behind them, so you gain genuinely usable standing space and floor area, not just daylight.
Do you work on listed buildings and in conservation areas?
Yes. That work is detail-led: matching sightlines, glazing bar widths, cill projections and cheek finishes to what survives, and specifying timber, lead and natural slate rather than modern equivalents. We prepare the drawings and heritage statement for listed building consent alongside the planning application.
Can a dormer include an en-suite?
Very often, yes — a full-width or L-shaped dormer usually has enough floor area for a bedroom plus a shower room. The practical constraints are getting soil and waste down to an existing stack, and whether the head height over the shower tray works. Both are settled at survey.
What happens to my existing loft insulation?
It comes out. Insulation at ceiling-joist level is in the wrong place once the loft is a room — the thermal line moves up to the new roof and dormer build-up. We remove and dispose of the old quilt and insulate the new envelope, which is also what makes the room comfortable to use in August.
Find out what your roof will take
A free measured survey in Greater London tells you what is achievable, what it needs, and what it costs — before you commit to anything.