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New home foundation cost guide

The foundations to your house, garage or conservatory provide the solid base on which the structure rests. New home foundation costs can vary according to a range of factors, including the size of the building, the soil type, the kind of foundations you are laying and accessibility to the site itself.

In this cost guide, we break down the cost to install new foundations and include a checklist of everything you need to consider before going ahead with the job.

Average cost to install foundation (per square metre) £100 - £120

These figures are average costs and can be affected by a range of factors including the size of your new building, the soil conditions, type of foundations and the accessibility of the site.

The costs included are for building the new foundations, and don’t include any professional fees you may encounter.

What are the factors affecting the installation of new foundations?

Before we dig into the detail, laying foundations is covered by building regulations which means you will need approval from your local authority before any work can take place. Your architect and builder will usually take care of this.

You may also need to notify your neighbours if any works are adjacent to their property, as outlined in the Party Wall Act. We’ve not included the costs of an architect or any surveyors costs you may need to cover in this guide.

The costs in the table and this guide are from the online estimators at My Build Estimate – a professional estimating company monitored by the Royal Institute of Chartered Surveyors (RICS).

New foundation installation costs Cost per square metre
LowHigh
Strip foundations£100£120
Trench fill foundations£120£150

*These are estimated, average costs. Our prices have been researched widely online by the Checkatrade team and represent a ballpark average for your proposed project. Costs may vary by region, the scope of the project and indeed by the products you plan to use.

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Cost of foundations per metre

Install new home foundations

The cost of your new foundations is typically calculated per metre, and is affected by a variety of factors, including:

  • Type of subsoil – The soil subtype could dramatically affect the cost of your new foundations and dictate which type of foundation you need.
  • Type of foundation – There are four main types of building foundations: raft foundations, trench fill foundation, strip foundations and concrete slab foundations.
  • Size of the building/structure – The larger the structure, the more extensive the foundations, and the more it will cost to install them.
  • Accessibility of the site – Laying foundations involves a large amount of manpower, machinery and building supplies.

The standard depth of a foundation is approximately 1m and a width of 0.6mm. The average cost to install new foundations are:

  • Strip foundations – £100 – £120 per-metre
  • Trench fill foundations – £120 – £150 per-metre

(This is based on a width of 0.6m and includes excavation, cart away, and concrete costs)

The cost per square metre of raft and concrete slab foundations will need a building design before providing a costing because there are significant variables.

Install new home foundations cost guide image

Why is subsoil important?

The soil your property is built on will dictate the type of foundations that are suitable to use. For the purposes of building, the Government classifies subsoil into seven types:

  1. Rock
  2. Chalk
  3. Gravel and sand
  4. Clay
  5. Firm clay over soft clay
  6. Peat
  7. Filled ground

Your chosen tradesperson and building inspector will be aware of the type of soil your property is built upon and can provide advice before work begins.

What are the different types of building foundations?

There are four types of building foundations that may be used to underpin your home, including trench fill foundations, strip foundations, concrete slab foundations and raft foundations.

Trench fill foundations

Trench filled foundations are trenches that are filled just below ground level with concrete to provide a solid base for the structure. Trench fill foundations are simple to build and less labour intensive than other methods, which compensates for the higher cost of materials.

Strip foundations

When laying strip foundations, your builder will excavate a trench and lay a solid base of concrete. They will build up from this base in blockwork until they reach ground, when your builder can switch to laying bricks, stones or your choice of material.

Concrete slab foundations

Concrete slab foundations are foundations made from concrete which is either poured over the ground or laid in individual blocks. Slab foundations are cheap to lay and are very strong and hard.

Raft foundations

Raft foundations involve a solid concrete base (or raft) made up of reinforced concrete being poured on top of the soil covering the entire area of the building. It’s used when other methods, such as strip foundations, aren’t suitable – where soil pressure is low, for example.

What type of foundations do I need?

Digging foundations new foundations cost guide image

As part of your planning application, your architect, tradesperson, and structural engineer will be responsible for ensuring that the selected type and size of foundations meet the current guidelines for new buildings.

The building inspector will ensure that the foundations you are laying are correct for the type of building and the subsoil before you are allowed to build.

During the laying of foundations, your building inspector may visit the site to check their condition.

Need a quote?

If you are searching for the new foundation costs for comparison or want to know the foundation cost per square metre of your new home or extension, you’ll find the UK’s biggest database of trusted tradespeople here at Checkatrade.

Key takeaways when analysing new foundation costs

  • The average cost to lay foundations is £100 – £120 per square metre.
  • Total cost of foundations per metre depends on the size of the building, the condition of the soil, the type of foundation selected and the ease of access to the site.
  • All work must receive approval from your local authority
  • If you’re building close to neighbouring properties, you must gain party wall approval.
  • New foundation costs may vary across the UK.