Loft Conversion Carpentry: Dormers, Floor Strengthening, Stairs & Fire Doors

No. Loft conversion carpentry, as we carry it out, is the structural and fire-door carpentry inside the project — dormer framing, loft floor strengthening, forming the stair opening, and fitting any fire doors the conversion requires. Project management, the architect’s drawings, planning permission or Building Control applications, plastering, insulation, electrics and roofing are separate trades and responsibilities, usually coordinated by your architect, project manager or main contractor. We are brought in for the carpentry.

Yes. We cut the structural opening in the main roof slope, frame the dormer cheeks and front wall, and build the dormer’s own small roof structure, tying it into the surrounding rafters, all to the engineer’s or architect’s design and the approved planning drawings. Dormer carpentry sits at the crossover between loft and roof work — our roof carpentry and cut roofs pages cover the wider cut-roof construction a dormer ties into, if you want the fuller technical picture.

We build to a structural engineer’s design; we do not calculate loft floor loads ourselves. Strengthening an existing ceiling to take the extra load of a habitable loft room is a structural calculation, and it needs to come from a qualified engineer before we start fixing timber. If you do not have a structural design yet, we can recommend engineers we have worked alongside.

Building Regulations Approved Document K (stairs) asks for 2m of headroom as standard. Where that genuinely is not achievable in a loft conversion, a reduced headroom of 1.9m at the centre of the stair and 1.8m at the edge is acceptable. The maximum pitch for a private stair is 42°, and the rise and going of each tread need to sit within set limits — maximum rise 220mm, minimum going 220mm, and twice the rise plus the going between 550mm and 700mm. We frame the stair opening to whichever of these your stair design needs.

Only in specific circumstances. Approved Document K treats alternating tread stairs as acceptable where there is genuinely no room for a standard-compliant stair, where the stair serves a single habitable room (plus, optionally, a bathroom or WC that is not the only one in the dwelling), and the stair must still provide 2m of clear headroom. We frame the opening to suit whichever stair type the design calls for, and the stair itself — treads, strings and balustrade — is covered on our staircases page.

Where a loft conversion creates a new storey more than 4.5m above ground level, Approved Document B (fire safety) requires the full escape route from that storey to be addressed — fire-resisting doors, minimum E 20, and fire-resisting partitions, minimum REI 30, along the route, including upgrading existing doors where necessary. Escape-route doors also need to be self-closing and readily openable. We fit the doors a loft conversion needs as part of the carpentry package; the installation detail itself is covered on our fire doors page.

As part of loft conversion carpentry we form the structural stair opening — trimming the joists, setting out the headroom and the pitch the stair needs to clear. The stair itself, whether a straight flight, a winder, or an alternating tread design, along with its balustrade and finish, is a separate scope covered on our staircases page. We coordinate the two so the opening is cut to exactly what the stair needs.

We carry out loft conversion carpentry across Berkshire, Surrey and South Buckinghamshire, including Ascot, Bracknell, Windsor, Maidenhead, Reading, Wokingham, Sunningdale, Virginia Water, Camberley, Stoke Poges and Gerrards Cross.