Dormer windows in Cardiff
Our teams install dormer windows and dormer loft conversions throughout Cardiff, handling structure, weatherproofing, glazing and finish as one job with one point of contact.
Dormers on Cardiff roofs
Because Cardiff 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.
We survey the roof before quoting anything. Ridge height, rafter span, purlin position and the condition of the existing structure decide which dormer forms are possible — and there is no substitute for a tape measure in the loft. The survey is free and carries no obligation.
Planning permission in Cardiff
If the property is in a conservation area or the dormer faces the road, a full planning application is needed. We prepare the drawings and handle the submission either way.
What we do across Cardiff
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.
- New dormers — flat roof, pitched, gable-fronted, hipped, shed, box, L-shaped, eyebrow and cat slide forms
- Full conversions — structure, staircase, insulation, plaster and building control sign-off
- Glazing — uPVC, timber, aluminium, sash and heritage-profile conservation windows
- Cladding and roofing — tile-hung, slate-hung, lead, standing-seam zinc, cedar and GRP
- Repairs — leak tracing, flashing renewal, rot repair and blown unit replacement
The quickest route is a photograph of the rear elevation over WhatsApp — we can usually tell you what is feasible before anyone visits.
Services in Cardiff
Every dormer type, locally
Flat Roof Dormers in Cardiff
The most space-efficient dormer — a flat-topped box that squares off the roof slope.
Learn morePitched Roof Dormers in Cardiff
A miniature pitched roof over the dormer — the traditional, period-correct option.
Learn moreGable-Fronted Dormers in Cardiff
A pitched dormer with a vertical gable face — the classic 'dog-house' front elevation.
Learn moreHipped Roof Dormers in Cardiff
Three sloping faces instead of a gable — softer, and often easier to get past planning.
Learn moreShed Dormers in Cardiff
A single shallow slope running with the main roof — wide, low and understated.
Learn moreFull-Width Rear Dormers in Cardiff
Wall-to-wall across the back of the roof — the biggest gain in usable floor area.
Learn moreL-Shaped Dormers in Cardiff
A rear dormer joined to a second over the outrigger — the Victorian terrace answer.
Learn moreBox Dormers in Cardiff
A simple squared projection — the workhorse dormer for bedrooms and bathrooms.
Learn moreEyebrow Dormers in Cardiff
A curved, brow-like swell in the roof — no cheeks, no vertical faces.
Learn moreCat Slide Dormers in Cardiff
The main roof continues down past the dormer — a soft, cottage-style profile.
Learn moreDormer Loft Conversions in Cardiff
The full job — structure, dormer, stairs, insulation, plaster and building control sign-off.
Learn moreBungalow Dormer Conversions in Cardiff
Turn a bungalow's roof void into a first floor — often doubling the footprint.
Learn moreVelux to Dormer Conversions in Cardiff
Already have rooflights? Convert the slope to a dormer and gain standing height.
Learn moreDormer Window Installation in Cardiff
Supply and fit of the window itself into new or existing dormer openings.
Learn moreDormer Window Replacement in Cardiff
Swap tired, draughty or rotten dormer windows without touching the structure.
Learn moreuPVC Dormer Windows in Cardiff
Low maintenance, well insulated and the most cost-effective frame for a dormer.
Learn moreTimber Dormer Windows in Cardiff
Engineered hardwood or softwood — the right answer on period and listed roofs.
Learn moreAluminium Dormer Windows in Cardiff
Thermally broken aluminium — the slimmest frames and the largest possible glass area.
Learn moreSash Dormer Windows in Cardiff
Vertical sliding sashes sized and detailed for a dormer opening.
Learn moreConservation Dormer Windows in Cardiff
Heritage-profile dormers and glazing for conservation areas and listed buildings.
Learn moreDormer Cladding in Cardiff
Re-clad tired dormer cheeks and faces in tile, lead, zinc, timber or GRP.
Learn moreGRP Fibreglass Dormer Roofing in Cardiff
Seamless glass-reinforced polyester on flat dormer tops — no joints, no seams.
Learn moreLead & Zinc Dormer Roofing in Cardiff
Traditional code lead and standing-seam zinc for dormer roofs, cheeks and flashings.
Learn moreDormer Window Repairs in Cardiff
Leaks, rot, failed flashings, blown units and draughts — diagnosed and put right.
Learn moreWhat homeowners say
Judged on the junctions, not the sales pitch
“The survey was the useful bit — he told us the ridge height wouldn't take what we'd been sold elsewhere, and offered a shed dormer instead. Glad we listened.”
— Homeowner, Cardiff“Scaffold went up on the Monday, roof was open and weathertight by the Thursday. No drama, no surprises on the invoice.”
— Homeowner, Cardiff“We'd had two leaks patched by other firms. They traced it to the back gutter in an hour and it hasn't come back since.”
— Homeowner, CardiffComments shown are representative of feedback received. Verified reviews are being collected from launch.
FAQs
Dormers in Cardiff — FAQs
Can a dormer include an en-suite?
Very often, yes — a full-width or L-shaped dormer usually has enough floor area for a bedroom plus a shower room. The practical constraints are getting soil and waste down to an existing stack, and whether the head height over the shower tray works. Both are settled at survey.
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.
Do I need planning permission for a dormer window?
Rear dormers on a house often fall under permitted development, provided the dormer is set at least 200mm back from the eaves, sits below the ridge line, uses materials similar in appearance to the existing house, and stays within the volume allowance — 40m³ for a terrace, 50m³ for a semi or detached. Front-facing dormers, flats and maisonettes, listed buildings, conservation areas and any property with an Article 4 direction all need a full planning application. We check the constraints on your specific address before we quote.
How long does a dormer take to build?
A single box or flat roof dormer is typically three to five weeks on site. A full-width rear dormer runs five to eight weeks, and an L-shaped dormer on a terrace with an outrigger is closer to seven to ten. A complete dormer loft conversion including the staircase, services and finishes is usually eight to twelve weeks from scaffold up to sign-off.
Does a dormer need building regulations approval?
Yes, always — permitted development covers planning, not building control. A dormer needs approval for structure, thermal performance under Part L, fire escape and protected route under Part B, and stairs under Part K if a staircase is involved. We handle the application, the inspections and the completion certificate.
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.
Find out what your roof will take
A free measured survey in Cardiff tells you what is achievable, what it needs, and what it costs — before you commit to anything.