Sash Dormer Windows in Surrey
If you are weighing up sash dormer windows in Surrey, we survey the roof, tell you what is actually achievable, and price it properly before anyone commits.
Sash Dormer Windows — indicative geometry
Sash Dormer Windows for Surrey homes
Because Surrey is largely large interwar detached and semi-detached houses with generous roof spans, the roof pitches and span widths we meet are fairly predictable, and that makes feasibility a quick conversation rather than a guess.
Dormers on Victorian and Georgian houses were sashes, and a casement in the same hole reads wrong from the pavement immediately. Spiral-balance or traditional cord-and-weight sashes are both available at dormer sizes, in timber or in slim heritage uPVC with run-through horns and putty-line profiles.
Key specification
| Operation | Spiral balance or cord and weight |
|---|---|
| Materials | Timber or heritage uPVC |
| Detailing | Run-through horns, putty-line, astragal bars |
| Glazing | Slim heritage units, 12–14mm |
Planning and building control in Surrey
Getting the consent route right at the start saves months. We establish whether it is permitted development, a lawful development certificate or a full application on the first visit.
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 Surrey use us
The completion certificate is part of the deliverable, not an afterthought. It is the document that makes the space count when you come to sell.
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 Surrey
FAQs
Sash Dormer Windows in Surrey — FAQs
Will my roof be open to the weather?
No. The roof is only opened once the scaffold, temporary weather protection and materials are all on site, and the dormer is made weathertight — structure, deck, membrane and temporary glazing — before the crew leaves at the end of the opening-up phase. We do not open a roof on a Friday afternoon.
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.
Find out what your roof will take
A free measured survey in Surrey tells you what is achievable, what it needs, and what it costs — before you commit to anything.