Trades Around
Renovation timeline planner · 2026

How long will your loft conversion actually take?

Converting roof space into a usable bedroom, ensuite or office. Build runs 4–14 weeks depending on type — the simplest Velux/rooflight conversion in a few weeks, a mansard or hip-to-gable with full planning closer to three months. Add 2–4 months on top for design, planning, building regs and the mandatory two-month party wall notice in most terraced/semi-detached homes.

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The plan

Loft Conversion

Converting roof space into a usable bedroom, ensuite or office. Build runs 4–14 weeks depending on type — the simplest Velux/rooflight conversion in a few weeks, a mansard or hip-to-gable with full planning closer to three months. Add 2–4 months on top for design, planning, building regs and the mandatory two-month party wall notice in most terraced/semi-detached homes.

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Type
Velux / rooflight (no roof shape change)
Ensuite
Bedroom/office only
Property
Detached
Planning
Permitted development
Week-by-week

Your timeline

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Phase
W-23
W-22
W-21
W-20
W-19
W-18
W-17
W-16
W-15
W-14
W-13
W-12
W-11
W-10
W-9
W-8
W-7
W-6
W-5
W-4
W-3
W-2
W-1
DAY 1
W1
W2
W3
W4
W5
W6
Pre-construction · before day 1
Architect drawings (concept & planning)
Submit full planning application
Submit Lawful Development Certificate
Structural engineer — steel & joist calcs
Submit Building Regs Full Plans
Tender — quotes from 3+ specialists
Serve party wall notice
Confirm builder & sign contract
Order Velux & dormer windows
Order steel beams
Order bespoke staircase
Scaffolding licence
On site · from day 1
Scaffold erection
Strip roof tiles & cut opening
Steel beam installation
New floor joists
Dormer / gable structural framing
Roof covering & cladding
Windows install (Velux & dormer)
Insulation
Stair opening & staircase install
First-fix electrics
Plasterboard & plastering
Second-fix electrics
Skirting, doors, decoration
Final building control inspection & sign-off
On-site trade workRegulatory / professionalDecision deadline (you act)Contractor prep / lead time
On-site total
4.6–4.8 weeks

On-site only. Add ~22 weeks of pre-construction (planning, ordering, lead times) before day 1.

Reality check

Where it tends to slip

If your project goes long, it’ll usually be one of these. Worth knowing before you sign anything.

01Party wall disputes — even with notice served, a dissenting neighbour and full party wall award can push the start by 4–8 weeks.
02Discovering inadequate existing roof structure (undersized rafters, sagging purlins) — additional steels or carpentry may be needed.
03Modern trussed-rafter roofs (typically post-1965 properties) need much more invasive structural work than traditional cut roofs.
04Bad weather during the open-roof phase — UK rain through the autumn/winter can delay roof strip and re-cover work; tin-hat scaffold helps but isn't waterproof.
05Steel beam fabrication backlog (2–3 weeks typical, longer in busy summer windows).
06Velux/rooflight stock issues — bespoke or oversized units carry 4-week+ lead times.
When you’re ready

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