Timber Frame Extension Cost & Prices 2021

Timber frame extensions are being used more and more. This is due to how quickly they can be built, their energy efficiency and the wide array of designs possible.

If you’re considering a timber frame extension or building, you may be wondering how much you should expect to pay.

This article will cover the costs involved and the sorts of factors that can alter these prices.

Timber Frame Cost per m²

A structural timber frame can be priced at £150/m² of the gross internal floor area.

Included within this timber frame cost is vertical studs with plywood sheathing to form internal and external walls, horizontal joists and sheathing to form upper floors and roofing and roof trusses.

This rate is for the south-east or southern London area. Price adjustments based on location are detailed within the factors section.

Timber Frame Extension Cost per m²

Below are the average costings of all the elements needed to create a timber frame extension:

ElementWork Included in ElementCost
SubstructuresStrip Foundations, Blockwork / Engineered Brick Cavity Walls, DPC, Concrete Slab, hardcore, blinding, DPM, insulation, screed £110/m²
Frame Timber Frame Structure - including stud walls, roof trusses, upper floor structure£150/m²
Roof Roof coverings including battens, membranes, insulation, felt, tiles, soffit, fascia & rainwater goods£124/m²
StairsIf required£19/m²
External WallsSIPS (studs in frame) - including insulation, OSB board, membranes, plasterboard. Chimneys£119/m²
Windows and External DoorsuPVC windows / doors£114/m²
Internal Walls & PartitionsPlasterboard and insulation (studs in frame)£60/m²
Internal DoorsSoftwood internal doorsets, ironmongery and decoration£67/m²
Wall FinishesPaint, wall tiling, skim etc£36/m²
Floor FinishesCarpet, tiling, hardwood flooring, skirtings etc£46/m²
Ceiling FinishesPlasterboard and skim£28/m²
Furniture, Fixtures, and EquipmentStove, Kitchens, Bathrooms, Wardrobes, shelving etc£115/m²
MechanicalHeating & Plumbing£75/m²
ElectricalElectrics & Lighting£82/m²
External WorksStorm & foul drainage, water & sewage connections£55/m²
Sub- Total£1200/m²
Design Team & Survey Fees£120/m²
PrelimsScaffolding, welfare, warranties and site attendances £120/m²
Total £1,440/m²

Therefore, for an average single-storey timber frame extension of 4m x 5m, £28,880 would be a good price to budget for.

Factors Affecting the Cost of TImer Frame Extensions

  • The number of storeys. When timber frames are used for structures higher than two storeys this can often increase cost per m². This is because of more structural timber required at lower levels to support the structure.
  • Specification of the system selected. This includes elements like the size of timbers, type of plywood and the thickness of plywood. All vary in price and can cause cost differences.
  • Weight of the structure. If heavy loads need to be supported heavy loads, more timber is needed to adequately support the structure, thus increasing cost.
  • Level of design required prior to construction. In particularly complex timber frame structures more time can be spent by a designer / structural engineer on drawings and design, thus increasing the system cost.
  • Location. The above rates are for the South East/Outer London Area. You can use the following adjustments depending on where you live. These are based on the BCIS and Spon indices.
Region% Adjustment
South East (Southampton, Oxford, Kent, Outer London)0
Inner London+4%
South West (Bristol, Exeter)-4%
West Midlands (Birmingham)-10%
East Midlands (Northampton, Nottingham, Leicester)-10%
East Anglia (Cambridge, Norwich, Ipswich)-5%
North West (Liverpool, Manchester)-12%
Yorkshire and Humberside (Leeds, Sheffield)-11%
North East (Newcastle, Sunderland)-10%
Scotland (Edinburgh, Glasgow)-6%
Wales (Cardiff, Swansea)-9%
Northern Ireland (Belfast)-12%

Do You Need Planning Permission?

Maybe. This depends on whether your extension fits within the size and position criteria. If it meets the criteria you may be able to extend under Permitted Development Rights (PD). If the extension is outside the scope of PD, then planning permission is needed.

It’s best to be on the safe and check with your local authority before starting work.

Get Prices on Timber Frame Extensions Near You

Timber extensions are still relatively new in the UK market. This means finding professional builders specialising in timber frames can be difficult.

We work with all the best timber frame extension builders ready to price your job. Get free, no-obligation quotes in your local area and compare prices using the form below.

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