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Self Build House Cost Estimating Services UK

A self build is one of the most significant financial commitments a person will make. Getting an independent, element-by-element cost plan before you break ground is the single most important thing you can do to protect that investment.

check Full cost plan from groundworks to final fit-out
check All hidden costs and professional fees identified
check Suitable for lender, planning and tender purposes
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±5%
Estimate Accuracy
10–48 Hours
Days Turnaround
3,000+
Projects Costed
Self build house under construction UK

Why Self Build Projects Need a Professional Cost Plan

Self build projects have a higher rate of budget overrun than almost any other residential project type. The reason is straightforward: most self builders approach the project with a construction cost in mind, but without a proper picture of all the costs that sit around it. Site purchase, groundworks, professional fees, planning and building regulations, VAT, landscaping, utilities connections and contingency can collectively add 30 to 50 percent on top of the build cost itself.

A self build estimate from us is not a square metre rate multiplied by your floor area. It is a document that works through every stage of the project, from site preparation and foundations through to second fix joinery and external works, using your actual drawings and specification. Each cost centre is priced separately so you know exactly what you are committing to and where the risks sit.

This level of detail also matters when approaching self build mortgage lenders. Most specialist lenders require a professional cost plan broken down by stage as a condition of their offer. A credible, independently produced estimate carries significantly more weight than a builder's quote or a calculator figure.

On specification: one of the biggest lessons from self build projects is that internal specification is where budgets most commonly overrun. Staircases, kitchens, bathroom fit-outs and flooring all carry enormous cost ranges depending on what you choose. We cost these elements at three specification levels in every estimate, so you can see the full budget impact of your choices before you commit.

If you are still at the plot purchase stage and are not yet sure your budget will support the house you want to build, a feasibility cost plan based on outline drawings is a straightforward starting point. We work with self builders at every stage, from initial land appraisal through to pre-tender bills of quantities, so contact us to discuss where in the process you are.

Our residential construction cost estimating service covers all self build types including timber frame, traditional masonry, structural insulated panels, and oak frame construction.

What We Cost at Each Stage

A self build cost plan follows the project from the ground up. Each stage is priced as a separate section so that a cost overrun in one area is immediately visible against the overall budget.

terrain
Groundworks and Foundations

Site clearance, excavation, foundation type (strip, raft, pad or piled), drainage runs, and external ground preparation. Soil conditions and topography are the biggest variables at this stage.

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Superstructure and Frame

External walls, structural frame, floor construction and roof structure. Costs vary significantly between timber frame, masonry, oak frame and SIP construction methods.

roofing
Roof and External Envelope

Roof covering, flat roof elements, windows and external doors, insulation, external render or cladding system, and airtightness measures required for current Building Regulations.

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Mechanical and Electrical

Full M&E design allowance, first and second fix, heating system, underfloor heating where specified, ventilation, solar PV, EV charging, and utility connections from the boundary.

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Internal Finishes and Fit-Out

Plastering, floor finishes, staircases, kitchen, bathrooms, joinery and painting. Costed at three specification levels with the cost difference between them clearly shown.

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External Works and Landscaping

Driveway, paths, boundary treatment, landscaping, and any outbuildings or garages. Frequently underestimated on self build projects and included as a clearly labelled line item.

The Three Build Routes We Estimate

The route you choose affects how the cost plan is structured and what assumptions we make on labour versus materials.

01

Main Contractor Build

A single contractor takes responsibility for the whole project. The cost plan feeds directly into a formal tender document. We produce bills of quantities for this route where required.

02

Project Managed Sub-Contract

You manage the project directly, appointing individual trades and suppliers. The cost plan is broken down by trade package so each appointment can be benchmarked against budget as the project progresses.

03

Package or Kit Build

A package company supplies the structural kit and sometimes manages construction. We include the package cost alongside all the elements the package does not cover, giving the true total project cost.

Costs Self Builders Regularly Underestimate

These six areas catch out even experienced self builders. We include every one of them in every self build cost plan we produce.

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Planning and Legal Fees

Planning application fees, building regulations drawings, structural engineer fees, CDM principal designer, SAP energy assessments, and air pressure testing. These are mandatory costs, not optional extras.

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Utilities and Connections

Connecting water, electricity, gas, and telecoms from the boundary to the building. On rural plots this can be a very significant cost, especially where services are not already adjacent to the plot.

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Highways and Access

New dropped kerbs, highway agreements, and Section 38 or Section 278 agreements with the local highway authority. Required on most plots with new or modified road access.

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VAT Recovery and CIL

New build houses qualify for VAT zero-rating on construction works, but the recovery process requires careful record-keeping from day one. Community Infrastructure Levy (CIL) self build exemptions must be applied for in advance.

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Site Preliminaries

Temporary site access, site hoarding and security, welfare facilities, scaffolding, skip hire, and plant hire. These are typically 8 to 12 percent of the construction cost and are often missing from early budget estimates.

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Contingency Allowance

First-time self builders should carry at least 15 percent contingency. Experienced self builders with well-developed designs can work to 10 to 12 percent. The right figure depends on site complexity and how developed the specification is at the point of estimate.

Self Build Estimating FAQs

At what stage of the self build process should I get a cost plan?expand_more
The earlier the better, but the level of detail we can provide depends on how developed your design is. At sketch or feasibility stage, we can produce a reliable budget cost plan based on floor area, build route and specification level. This is useful for confirming plot viability before you commit to purchase. Once planning drawings are complete, we can produce a more detailed cost plan by element. For a pre-tender estimate with bills of quantities, we need full architectural and structural drawings. We are happy to advise on what level of estimate is appropriate for where you are in the process.
Do self build mortgage lenders require a professional cost plan?expand_more
Yes, the majority of specialist self build mortgage lenders require a detailed cost plan broken down by stage as part of their underwriting process. Lenders use this to set the drawdown schedule, as funds are typically released in stages tied to completion of defined build milestones. A professionally produced estimate that covers all costs including preliminaries, professional fees and contingency carries considerably more weight than a builder's quote or an online calculator figure. We can format the cost plan to align with the stage payment structure your lender requires.
We are building in a rural location. Does that affect the estimate significantly?expand_more
Rural sites often carry higher costs in a few specific areas. Utilities connections can be substantially more expensive where services are not already close to the plot boundary, particularly for off-grid or remote locations where a private sewage treatment plant and borehole water supply are needed. Site access and transport of materials adds cost if the plot is difficult to reach. We also apply regional labour rate adjustments, which vary across the UK from Northern Ireland through to London and the South East. All of these factors are accounted for in the estimate rather than using a blanket national rate.
Can you produce a cost plan for a timber frame or oak frame self build?expand_more
Yes. We estimate self builds across all construction methods including traditional masonry, timber frame, structural insulated panels (SIPs), oak frame, and modular or offsite construction. The approach to costing differs by method. Timber frame and SIP builds typically have a higher upfront material cost but shorter on-site build programme, which reduces preliminary costs. Oak frame buildings often involve a significant bespoke design element that affects both material and labour costs. We structure the estimate to reflect how costs fall under your specific build method.
How does a self build estimate relate to a new build house estimate?expand_more
The construction cost methodology is the same, both are new build residential projects and are costed using the same element-by-element approach. The difference is context. A self build involves a single client managing a complex project themselves, often for the first time, which means the cost plan needs to work harder as a project management tool throughout the build. Our new build house cost estimates service covers developer-led new build projects, while this service is specifically structured for clients taking a direct role in their own build project.

Related Residential Estimating Services

Ready to get your self build properly costed?

Send us your drawings and a description of your build route and specification. We will review the project and confirm turnaround within 10 hours.

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