Renovate or Convert - Build cost calculator

Download the 2010 Build Cost Guide at the bottom of the page

Your Build Route

Your level of involvement in the project will influence the build costs. For simplicity, the four most common build routes have been identified below.

Build Route A: Building on a largely DIY basis, substi­tuting around 30% of labour costs with DIY, and employing help with the rest of the building work. Materials pur­chased directly.

Build Route B: Building using trades­people hired directly. Minimal DIY involvement. Most materials purchased directly.

Build Route C: Building using a main contractor or package supplier to complete the structure to a weathertight stage, with the remaining work being under­taken by subcontractors with most materials purchased by self-builder direct from suppliers.

Build Route D: Building using a main con­trac­­tor. Building in this way requires the least involvement from the self-builder.

Build Quality

The standard of specification that you choose will have an enormous influence on your build cost. For estimating purposes, three general categories of quality have been identified:

Standard: This represents a basic build quality equivalent to that offered by most speculative developers. Cavity walls: facing bricks (£250/1,000 or £45/m2 laid), insulation, and 100mm block­work; concrete interlocking tiles (£28/m2 laid); standard softwood joinery; studwork partitions; contract kitchen; basic sanitaryware; and radiator central heating.

Good: This is equivalent to that offered by quality developers. Cavity walls: facing bricks (£450/1,000 or £56/m2 laid), insulation, and 100mm blockwork; clay machine-made tiles (£36/m2 laid); high-end off-the-shelf softwood joinery; blockwork partition walls; top-of-the-range contract quality kitchen; quality sanitary­ware; and underfloor heating (UFH) downstairs.

Excellent: A very high stan­dard. Cavity walls: bricks (£650/1,000 or £67/m2 laid), insulation, and 100mm blockwork; plain clay tiles (£45/m2 laid); hardwood joinery; blockwork partitions; bespoke kitchen; quality sanitaryware; UFH.

Make Adjustments

Having found your rate (£/m2) from The H&R Average Build Cost Guide make any adjustment for quality or unusual mate­rials that may be necessary (see below) and then multiply the adjusted £/m2 by the gross internal floor area of your design to calculate a build cost estimate.

Using Roof Space: Using roof space to provide accom­­moda­tion is less expensive than adding a full extra storey. For estimating purposes, calculate the cost separately by multi­plying the additional useable gross floor area by 70% of the average £/m2 for the house.

Basements: For estimating purposes, treat basements as above-ground space and include them as part of your measurement of gross internal floor area.

Facing Materials: Alternative facing mat­erials will have a direct influ­ence on overall build costs. To adjust for this you need to add or subtract an allow­ance/m2 for your chosen wall cladding from the sum allowed for cladding within your chosen specification. For render on blockwork allow £25/m2; for timber cladding allow £25/m2; for hand­made weather tiling allow £54/m2; for rubble walling/flint allow £90/m2; for reconstituted stone allow £48/m2; for natural stone allow £75/m2.

Roofing Materials: Alternative mate­rials will affect your over­all build costs. To adjust for this, add or subtract an allowance/m2 for your material from the figure allowed in your chosen level of Build Quality (e.g. £28/m2, £36/m2 or £45/m2). For new Welsh slate allow £60/m2; for second-hand slates allow £35/m2; for handmade clay tiles allow £65/m2; for reed thatch allow £80/m2.

Sloping Sites: For estimating purposes, allow an additional £10/m2 for every degree of slope.

Bespoke Joinery/Kitchen: To adjust for bespoke handmade windows and doors, or a kitchen, add the quote (excl VAT) to your estim­ated build cost, less the allowance of £40/m2 already in the costs.

Ceiling Heights: For every 0.1m of additional ceiling height (on top of the standard 2.4m) add 1% to your £/m2.

Garages and Outbuildings: Although an integ­ral garage is unlikely to be completed to the same standard of finish as the rest of the property, for these purposes include integral garages within your mea­sure­ments of the living area.

Don’t Forget the Extra Fees

• Legal Fees: £500-1,000
• Stamp Duty and Land Tax: The tax is cur­rently levied at 1% for plots valued from £175,001 to £250,000, 3% for plots valued from £250,001 to £500,000 and 4% over £500,000
• Topographical Site Survey: Typical cost £350-500
• Design Fees: Architects charge 7-15% of the total build cost for a ser­vice involv­ing design and supervision. For planning drawings from other sources expect to pay from £2,500-3,500, plus a similar figure for Building Regulations drawings
• Structural Engineers’ Fees: £400-500
• Planning Application Fees: £335
• Building Regulations Fees: £500-1,000
• Warranty: Around 1% of contract value
• Self-build Insurance: £500-800
• Services: Typically £3,500-6,000 total
• Demolition Costs: Typically £5,000-10,000
• External Works: Around 15% of total build cost

FAQs

How does Homebuilding & Renovating come up with the figures in the Build Cost Guide?
We established basis figures, based on a survey of all the case studies that appeared in the magazine, adjusted for our own experiences and knowledge. These base figures are then updated monthly using the Rebuilding Cost Guide indices published by the Building Cost Information Service.

How do I measure my intended new house?
Gross internal floor area is the measure we use (the industry standard). It’s the area measured to the internal face of each external wall for each floor level, including areas occupied by internal walls.

What do the figures include?
The cost per square metre figure allows for a finished home, including kitchens and bathrooms but not including external landscaping.

Do the figures include VAT?
As VAT is zero-rated for new builds (i.e. not payable), the figures do not account for it.

I’m renovating. Are these figures relevant?
Not really. They provide some guidance for major extensions which would include most of the key elements you would find in a new house (e.g. kitchens and bathrooms) but as they are usually relatively small and specific to a few rooms, they tend not to be relevant to these figures. Renovation costs depend very much on the extent of the work itself (e.g. some renovators will rewire, others not) and as a result it is impossible to generalise.

Further Reading:

• Cutting Costs: Reducing Material Costs
• How to Cut Costs Without Sacrificing Quality
• How Much Will Your Project Cost?

Attachment	(click to download)
	Buildcostguide2010.pdf