Comparing Ground Floor Structure Costs

timber floor joists
(Image credit: getty images)

For most self builders and extenders, one of the most exciting times is when the ground floor is completed and they can, at last, see the footprint of their new home on site.But there are choices to be made when it comes to the ground floor structure.

To a large extent, suspended timber ground floors gave way to solid slab concrete floors throughout much the 20th century and then, from around 1976 onwards, following a prolonged period of drought with many foundation and oversite failures, suspended concrete beam and block floors started to gain prominence. Nevertheless, all three systems remain valid and fall within Building Regulations.

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Suspended timber floor costs
5 rolls of damp-proof course at £3.16 each£15.80
2 rolls of polythene membrane£75.46
28 air vents£22.68
6m³ concrete oversite£626.58
Labour for above (groundworkers plus 1 labourer)£218.00
20m² honeycomb support walling blocks£136.00
Labour and mortar£270.00
Floor joists 300m, 195x47mm treated£1,038.00
80 joist hangers @ £1.18 each£94.40
600m battening£186.00
44 sheets of 100mm insulation @ £32 each£1,408.00
44 sheets of 50mm insulation @ £19 each£836.00
Nails, etc. £69.94
Moisture-resistant decking — 84 sheets @£7.99 each£671.16
Labour (carpenter x 2 for 4 days)£1,280.00
Total: £6,948.02
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Solid slab oversite costs
200mm consolidated hardcore£120.00
Sand blinding£32.00
44 sheets of 100mm insulation @ £32 each£1,408.00
44 sheets of 50mm insulation @ £19 each£836.00
Perimeter insulation£100.37
6m³ concrete oversite£626.58
Mesh reinforcement£434.50
Labour for above (groundworkerplus labourer for 4 days)£872.00
Digger (2 days)£432.00
Pre-mix screed (labour and materials)£1,930.25
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Beam and block floor costs
28 remote void adaptor vents£169.12
28 telescopic air vents£92.68
28 air bricks£22.68
Labour for above£436.00
Floor beams by specialist manufacturer£2,231.25
Crane (1 day)£425.00
Floor blocks 112.9m²£767.72
Labour for above (groundworker plus labourer for 9 days)£1,090.00
Perimeter insulation£18.72
44 sheets of 100mm insulation @ £32 each£1,408.00
44 sheets of 50mm insulation @ £19 each£836.00
Labour for above (1 day)£218.00
Pre-mix screed labour and materials£1,930.25
David Snell

David is one of the UK's leading self build and plotfinding experts, and a serial self builder who has been building homes for 50 years. The author of Building Your Own Home, David spent decades as a speaker and expert at self build exhibitions such as the Homebuilding & Renovating Show. He has recently finished his fourteenth self build project.