Dormer windows in Llanishen
From the first measured survey to the completion certificate, we run dormer windows and dormer loft conversions projects in Llanishen as a single, managed piece of work.
What we build in Llanishen
The housing stock around Llanishen 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.
Whether that is a single flat roof dormer to make a back bedroom usable, or a full-width rear dormer with a bedroom and en-suite, the process is the same: a free measured survey first, a fixed written price second, and nothing else until you have both in front of you.
Planning permission in Llanishen
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.
Llanishen sits in Cardiff, and local authority interpretation of the volume allowance does vary — which is why we check the planning history at your specific address rather than assuming the neighbours' dormer sets a precedent.
How the job runs
Design and consent
Measured drawings, elevations and sections. We submit the planning application or lawful development certificate and the building regulations application.
Structure
Ridge beam and floor steels craned or manhandled in, new joists laid, the dormer frame built and sheathed.
Glazing
Windows fitted square, sealed and drained, with escape-compliant opening lights where required.
Survey and feasibility
A specialist measures the roof, checks ridge height, span and structure, and confirms whether you are inside permitted development.
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. Book the survey, get the fixed written price, and decide in your own time. Nothing about that process commits you to anything.
Popular in Llanishen
Dormer work we are asked for most
Bungalow Dormer Conversions
Turn a bungalow's roof void into a first floor — often doubling the footprint.
Learn moreuPVC Dormer Windows
Low maintenance, well insulated and the most cost-effective frame for a dormer.
Learn moreConservation Dormer Windows
Heritage-profile dormers and glazing for conservation areas and listed buildings.
Learn moreDormer Window Repairs
Leaks, rot, failed flashings, blown units and draughts — diagnosed and put right.
Learn moreHipped Roof Dormers
Three sloping faces instead of a gable — softer, and often easier to get past planning.
Learn moreBox Dormers
A simple squared projection — the workhorse dormer for bedrooms and bathrooms.
Learn moreFAQs
Dormers in Llanishen — FAQs
Do you handle the planning application?
Yes. We prepare measured drawings, elevations and sections, submit the application or the lawful development certificate, and deal with the case officer's queries. On conservation and listed work we also put together the heritage justification the application needs.
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.
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.
Do you work on listed buildings and in conservation areas?
Yes. That work is detail-led: matching sightlines, glazing bar widths, cill projections and cheek finishes to what survives, and specifying timber, lead and natural slate rather than modern equivalents. We prepare the drawings and heritage statement for listed building consent alongside the planning application.
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.
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 Llanishen tells you what is achievable, what it needs, and what it costs — before you commit to anything.