Box Dormers in Gwynedd
If you are weighing up box dormers in Gwynedd, we survey the roof, tell you what is actually achievable, and price it properly before anyone commits.
Box Dormers — indicative geometry
Box Dormers for Gwynedd homes
Because Gwynedd is largely Victorian and Edwardian terraces, interwar semi-detached houses and post-war bungalows, the roof pitches and span widths we meet are fairly predictable, and that makes feasibility a quick conversation rather than a guess.
A box dormer is the plainest form there is: two cheeks, a flat or very shallow top, and a flat front. There is nothing clever about it, which is precisely the point — fewer junctions means fewer places to leak, and a shorter programme on site. Most single-room dormers on post-war housing are box dormers whether or not anyone calls them that.
Key specification
| Typical projection | 1.5m – 3.5m wide |
|---|---|
| Depth | 1.8m – 3.0m into the roof |
| Roof finish | GRP, EPDM or felt |
| Cheek finish | Tile-hung, GRP or vertical cladding |
Planning and building control in Gwynedd
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 Gwynedd 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.
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 Gwynedd
FAQs
Box Dormers in Gwynedd — FAQs
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.
Do dormer windows need to be fire escape windows?
In a loft conversion, at least one window in each habitable room generally needs to meet escape requirements — a clear opening of at least 0.33m², minimum 450mm in both height and width, with the bottom of the opening between 800mm and 1100mm above floor level. We specify the opening lights to meet this as standard.
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.