Where’s the job?

Scope of Works

• survey and set out the extension footprint and levels, check party walls and boundaries

• prepare and install temporary protection and scaffolding or access towers as required

• construct structural roof elements (timber joists, trusses or steel beams) and upstands

• install insulation, vapour control layer and create designed fall for drainage

• apply waterproof covering (EPDM, torch-on or GRP) and fit outlets, flashings and gutters

• fit finishes such as fascias, soffits, rooflights and complete site tidy and waste removal

• coordinate with structural engineer, building control and arrange waterproofing handover

Typical Cost

Time on Site

Typical build time for a single‑storey flat roof extension is 2–6 weeks on site depending on size, groundworks and whether structural steel is required; inspections and sign‑offs can add time and prolonged wet weather will extend the programme

Questions to Ask Your Tradie

• How many flat roof extensions have you completed and can you show recent examples?

• What waterproofing system do you recommend and what guarantee do you provide?

• Who organises structural calculations and building control sign‑off, and is that included in the quote?

• Will you provide a written schedule of works, payment milestones and expected start/completion dates?

• Are scaffolding, waste removal and site protection included or charged separately?

• What PPE and contamination controls will your team use, and how do you manage dust and noise for neighbouring properties?

How to Avoid Surprises

• check access and parking near the build and arrange permits if required

• confirm who provides scaffolding and whether neighbours need notices

• ask for lead times on key materials (membrane, rooflights, structural steel)

• confirm waste disposal arrangements and skip placement before work starts

• make neighbours aware and check any party wall agreements or restrictions

• secure pets and clear internal areas where trades will work to protect finishes