Sash Dormer Windows in Gwynedd
Gwynedd homeowners come to us for sash dormer windows that are properly detailed at the junctions — because that is where dormers succeed or fail.
Sash Dormer Windows — indicative geometry
Sash Dormer Windows for Gwynedd homes
Most of the dormer work we take on around Gwynedd is on Victorian and Edwardian terraces, interwar semi-detached houses and post-war bungalows, where the ridge height and the position of the existing purlins set the limits.
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 Gwynedd
Rear dormers on houses often sit inside permitted development, but the volume allowance is consumed by any previous loft or rear extension — so we check the planning history for the address before we say yes.
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 Gwynedd use us
We would rather tell you at survey that your ridge height will not take what you want than take a deposit and find out in week three.
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 Gwynedd
FAQs
Sash Dormer Windows in Gwynedd — FAQs
Why is my dormer leaking?
In our experience the window itself is the cause less than a fifth of the time. Far more often it is the apron flashing at the dormer front, the lead soakers where the cheeks meet the roof slope, the back gutter behind a pitched dormer, or a split at an upstand in the flat covering. Water then tracks along a rafter and appears somewhere else entirely, which is why we trace the path before quoting.
Will a dormer add value to my house?
A properly built and signed-off dormer conversion adding a bedroom and bathroom typically returns a meaningful share of its cost in value, and more in areas where floor space is scarce. The building control completion certificate is what makes the space count as habitable floor area on a valuation — without it, surveyors will not include it.
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.
Find out what your roof will take
A free measured survey in Gwynedd tells you what is achievable, what it needs, and what it costs — before you commit to anything.