Dormer Window Replacement in West Sussex
We design, build and weatherproof dormer window replacement for homeowners across West Sussex, working from first survey through to building control sign-off.
Dormer Window Replacement — indicative geometry
Dormer Window Replacement for West Sussex homes
West Sussex is a mix of Victorian and Edwardian terraces, interwar semi-detached houses and post-war bungalows, and each of those wants a different dormer form — which is why we survey before quoting rather than pricing off a photograph.
Most dormer windows fail long before the dormer does. Rotten timber sills, blown double-glazed units, seized hinges and perished seals are all replaceable in a day or two without disturbing the cheeks or roof. We survey the surrounding timber first — there is no point putting a new frame into a rotten sub-sill, and that is where a lot of cheap replacements go wrong.
Key specification
| Typical duration | 1–2 days per dormer |
|---|---|
| Scaffolding | Tower or scaffold depending on height |
| Sub-sill check | Timber probed and replaced if soft |
| Glazing upgrade | 1.2 W/m²K or better |
Planning and building control in West Sussex
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 West Sussex 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.
If you want to know what your roof will actually take, the survey is free and there is no obligation attached to it.
Other dormer work in West Sussex
FAQs
Dormer Window Replacement in West Sussex — FAQs
What is the best roof covering for a flat dormer?
GRP fibreglass and EPDM rubber are the two we specify most. GRP cures into a single seamless laminate with bonded trims and suits small tops with several upstands. EPDM is a one-piece membrane that copes better with movement on larger spans. Both carry twenty-year guarantees; mineral felt is cheaper but has a materially shorter life.
What insulation do dormers need?
Current building regulations want around 0.15–0.18 W/m²K for a new dormer roof and 0.18 W/m²K for the cheeks and front. In practice that is a warm-roof build-up using 100–150mm of PIR insulation above or between the structure, with a continuous vapour control layer on the warm side. Getting the VCL continuous matters more than the insulation thickness.
Can you match my existing roof tiles?
Usually. Most common clay and concrete profiles are still in production or available reclaimed, and we source a match at survey stage so you see it before work starts. Where a discontinued profile cannot be matched exactly, we normally recommend taking tiles from a less visible slope for the dormer and using the closest new match on the hidden elevation.
Can you convert an existing Velux loft to a dormer?
Yes, and it is usually a shorter job than starting from scratch because the floor, staircase and services already exist. We verify the existing floor structure and any previous building control approval first, then cut and form the dormer into the finished room. Expect the room to be out of use for three to five weeks.
How disruptive is a dormer build?
Less than people expect, because most of the work happens above your ceilings and is reached from the scaffold. The noisy phases are opening up and installing steels, typically two to four days. Once the staircase is cut in there is dust and traffic through the house, and we sheet and protect the route for that period.
Find out what your roof will take
A free measured survey in West Sussex tells you what is achievable, what it needs, and what it costs — before you commit to anything.