This quotation sets out the work, the price and what is provisional. Please read the assumptions and exclusions before accepting.

What we will build

• Two-storey extension: 4m × 5m (external), two storeys, approximately 32.6 m² internal floor area.
• Walls: insulated cavity wall, block inner leaf finished in facing brick.
• Roof: pitched gable roof at 35° in concrete interlocking tile.
• Foundations and floor: trench-fill foundations, concrete slab with insulation.
• Windows and doors: 1 × french doors 1.8×2.1m, 1 × window 1.2×1.2m, 2 × window 1.2×1.2m.
• Completed to: complete finish (standard specification).
• Services: 14 power points, 10 light fittings, radiators from the existing system, plumbing for bathroom.

Price breakdown

About the provisional sums

These are estimates for items that cannot be priced firmly yet. They are confirmed with you before that work starts.

• Steel beam and structural design for 1 × 2.4m opening: A load-bearing opening into the existing house needs a structural engineer's design, a steel beam with padstones and building control sign-off. Allowance covers design and steel supply; the builder's work is priced below.

Assumptions this price relies on

• The new first floor is tied into the existing house wall; a doorway is formed through the existing first-floor wall (non load-bearing assumed).
• Foundations: trench fill 600mm wide × 1.0m deep in GEN1 concrete under all new external walls.
• Ground floor: 100mm concrete slab on 150mm compacted hardcore with 100mm PIR insulation.
• External walls: facing brick outer skin, 100mm full-fill insulated cavity, 100mm block inner skin.
• Drainage: rainwater and any foul water connected to the existing system within 6m, capacity assumed adequate. Building over or near an existing sewer needs the water company's agreement.
• The existing consumer unit has spare capacity for the new circuits; if not, a new unit is extra.
• Heating: 2 radiators added to the existing system; the existing boiler is assumed to have capacity.
• First floor: 47×225 C24 joists at 400mm centres spanning 3.7m, subject to building control.
• External walls: facing brick outer skin, 100mm full-fill insulated cavity, 100mm block inner skin.
• Gable roof at 35° on manufacturer-designed trusses, covered in concrete interlocking tile. Truss price is an allowance until the manufacturer quotes.
• The existing consumer unit has spare capacity for the new circuits; if not, a new unit is extra.
• Heating: 2 radiators added to the existing system; the existing boiler is assumed to have capacity.
• No planning application fee, party wall surveyor or planning drawings are included. Permitted development or existing consent is assumed.
• Work to comply with the building regulations applying in England; design by others where a design is required.

Not included

• Planning application, drawings and party wall matters
• Furniture, appliances and loose fittings
• Landscaping and reinstatement beyond the working area
• Anything found on opening up that could not be seen at survey
• Alterations to the existing first floor beyond forming a doorway

Programme, validity and payment

• Estimated time on site: about 8 weeks, subject to weather, materials and approvals.
• Payment in stages:

  Deposit on acceptance	10%	£8,007.36
  Watertight shell	40%	£32,029.44
  First and second fix complete	30%	£24,022.08
  Completion and handover	20%	£16,014.72

• Payment: Each stage is invoiced when it is reached and is due within 7 days.