Answer four quick questions and get an instant indicative cost estimate — benchmarked against real 2025 Hertfordshire builds. Used by landowners, homeowners and private clients to pressure-test a project before committing to an architect, a builder, or a site.
What Will Your Bespoke Home Actually Cost?
Federation of Master Builders
30+ Years · 100+ Projects
Development of the Year
DEAL of the Year
An Honest Starting Number — Before You Commit
Most bespoke builds in Hertfordshire run £80,000 to £250,000 over original quote — almost always because nobody produced a realistic cost figure before the architect drawings, the planning submission, and the site acquisition were committed.
This tool is designed to flip that sequence. Four questions — project type, size, finish level, location — and you’ll see an indicative figure for the kind of project you’re considering, benchmarked against what we’ve delivered across Hertfordshire and the South East in 2025.
No sales call. No brochure gate. No login. Just a realistic starting number you can use to test whether your thinking is aligned with the market, before you spend a penny on professional fees.
If the number is useful, we can talk about our four-stage process — the same discipline that lets us offer a Fixed Price Guarantee and a Completion Date Guarantee before a single brick is laid.
What are you planning to build?
Choose the option that best fits your project.
A Word from Our Founder
Kevin Edge founded Mosaic Bespoke after more than 30 years delivering residential construction and property development across Hertfordshire — over 100 completed projects, a Postgraduate Certificate in Project Management, and a track record recognised with Deal of the Year and Development of the Year industry awards. His work has been featured on BBC Radio and television.
He leads a small, deliberately focused team — including Nick Boorer FCIOB (Master Builder of the Year), David Stillwell MCIAT (20 years at Mosaic, leading architectural design), and Oliver Crudgington (17 years estate agency, specialising in land and plot identification).
The estimate you receive from this tool is benchmarked against the projects this team has delivered, in the locations our clients are building.
What Your Estimate Includes — And What It Doesn't
Included
- Construction cost benchmarked against 2025 Hertfordshire builds
- Adjustment for project type, size, finish and location
- Build-cost range reflecting realistic high/low delivery scenarios
- Indicative figure to test your site or budget before committing further
Not Included
- Land or plot purchase cost
- Professional fees (planning, architecture, structural engineering)
- VAT — new builds are typically zero-rated, we manage the reclaim
- Interior design, soft furnishings, bespoke joinery
- External works, landscaping, boundary treatments
- Site-specific conditions uncovered by survey
A properly evidenced cost figure comes from our Stage 1 Opinion of Probable Cost — a structured review taking one to two weeks, benchmarked against your specific site and brief. Free, no-obligation, and the first step for most clients who progress beyond the estimator.
What Happens After Your Estimate
01
Discover
Opinion of Probable Cost
Understand what your home is likely to cost before committing further. Typically 1–2 weeks.
02
Define
Feasibility Study
Assess planning risk, site constraints and financial exposure. Typically 4–6 weeks.
03
Prepare
Pre-Construction Agreement
Coordinate design, engineering and cost control before build begins. Typically 8–16 weeks.
04
Deliver
Construction and Delivery
Build your home with one accountable, structured team.
Built by the Same Team That Ran the Numbers
Common Questions
How accurate is the estimate?
It is indicative. The calculator uses 2025 Hertfordshire build benchmarks adjusted for project type, size, finish level and location — enough to test whether your budget is in the right territory for what you want to build. An accurate figure for your specific project requires a Stage 1 Opinion of Probable Cost, which takes us 1–2 weeks once we’ve reviewed your site and brief.
What happens after I submit my details?
You’ll receive an email with your estimate and our brochure immediately. A member of our team will be in touch within one working day for a short, no-obligation conversation about your project — if useful, we’ll talk through next steps.
Why is VAT excluded?
For qualifying new-build residential projects in the UK, VAT is typically zero-rated — we manage the reclaim process on your behalf. For extensions and renovations, VAT treatment varies depending on the nature of the works, and we’ll explain this properly at the Free Project Appraisal stage.
Do you work outside Hertfordshire?
Our primary service area is Hertfordshire — Harpenden, St Albans, Radlett, Berkhamsted, Welwyn Garden City, Potters Bar, Hemel Hempstead, Wheathampstead, Chorleywood and the surrounding towns. We also undertake select projects elsewhere in the South East and Greater London. “Rest of UK” selections on the calculator are benchmarked but may fall outside our geographic capacity — we’ll be honest about that on the first call.
Ready for a Proper Figure?
If you have a site, a plot, or a property you’re ready to progress, the next step is a Free Project Appraisal — a 45-minute structured review of your site, your brief, and what the project will realistically take to build. No cost. No obligation.