Cat Slide Dormers in Berkshire
Berkshire homeowners come to us for cat slide dormers that are properly detailed at the junctions — because that is where dormers succeed or fail.
Cat Slide Dormers — indicative geometry
Cat Slide Dormers for Berkshire homes
The housing stock around Berkshire runs to Victorian and Edwardian terraces, interwar semi-detached houses and post-war bungalows — so the first question at survey is always which of those you have, because the structure underneath differs completely.
A cat slide (or 'sweeping') dormer lets the main roof plane run on below the dormer sill, so the dormer appears to emerge from the roof rather than to be planted on it. It is a rural and cottage idiom, and it works beautifully on long, low roofs where a box dormer would look brutal. Detailing at the sill and the sweeping valley is the whole job.
Key specification
| Typical width | 1.2m – 3.0m |
|---|---|
| Sweep | Main roof continues below sill line |
| Roof finish | Plain tile, slate or pantile |
| Critical detail | Swept valley and sill flashing |
Planning and building control in Berkshire
Whether you need planning permission or a lawful development certificate depends on the elevation, the volume already used and the local authority's Article 4 position — all of which we confirm before design work starts.
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 Berkshire use us
One quotation covers scaffold, structure, weatherproofing, glazing, plastering and sign-off. You are not coordinating four trades who each blame the last one.
Book the survey, get the fixed written price, and decide in your own time. Nothing about that process commits you to anything.
Other dormer work in Berkshire
FAQs
Cat Slide Dormers in Berkshire — FAQs
Is scaffolding included in the price?
Yes. Every quotation we issue includes scaffold design, erection, weekly inspection, hire for the programme and dismantling. Scaffold appearing as an extra afterwards is one of the more common complaints about dormer work, so we price it in from the start.
How wide can a dormer be?
Structurally, as wide as the roof — full-width rear dormers regularly run six to eight metres, carried on a steel ridge beam. The limits are usually planning volume allowances and the setbacks needed at eaves and ridge, rather than what can be built.
What guarantees do you provide?
Structural work carries a ten-year guarantee, GRP and EPDM flat roofing twenty years, windows ten years on frames and sealed units, and lead and zinc work is covered for workmanship for ten years. You also receive the building control completion certificate, which is the document that actually matters when you sell.
Can you build a dormer in winter?
Yes, with adjustments. Temporary weather protection over the scaffold lets structural work continue in most conditions. GRP roofing needs dry conditions above about 5°C to cure properly, so in a cold spell we either sequence it differently or specify EPDM, which is unaffected.
How much does a dormer window cost?
A single flat roof dormer typically runs from around £9,000 to £20,000 supplied and fitted, depending on width, cladding finish and access. A full-width rear dormer on a semi is usually £28,000 to £45,000, and a complete dormer loft conversion including stairs, insulation, plaster and building control sign-off is more commonly £40,000 to £70,000. Our online guide-price tool gives you an indicative range in about a minute.
Find out what your roof will take
A free measured survey in Berkshire tells you what is achievable, what it needs, and what it costs — before you commit to anything.