Fixed-price contracts
Fixed-Price Extension Builder, West Midlands
Kingdom Build is a fixed-price extension builder covering the West Midlands from Birmingham. After a free site visit we issue one written price for the whole extension — drawings, structural work, build and finishes — within 5–7 days. That figure is a contract, not an estimate, and every job carries a 12-month workmanship guarantee.
- Free site visit
- Quote in 5–7 days
- Fixed-price contract
- 12-month guarantee
Fixed-price contracts
Kingdom Build is a fixed-price extension builder covering the West Midlands from Birmingham. After a free site visit we issue one written price for the whole extension — drawings, structural work, build and finishes — within 5–7 days. That figure is a contract, not an estimate, and every job carries a 12-month workmanship guarantee.
What “fixed price” means on a Kingdom Build contract
An estimate is a builder's best guess before the work starts. A fixed price is a contract: one agreed figure for a defined scope, written down, and unchanged unless you deliberately change the scope. The difference matters most in the last third of a build, which is exactly when an estimate tends to drift and a fixed price does not.
We can commit to a number because we survey before we quote. The free site visit is where we find the things that move extension costs — where the drains run, what the existing foundations are like, whether the original rear wall is load-bearing, what the brick is. Once those are known, the price is set and the risk of getting them wrong sits with us, not with you.
The quote is itemised by category — structure, services, finishes and professional fees — so you can see where the money goes and compare it properly against anyone else's.
What the fixed price includes
One contract covers the whole extension from first drawing to completion certificate. You do not hold a separate contract with an architect, an engineer and a builder, and there is one project manager who owns the programme.
- Free initial site visit and feasibility check
- Architectural drawings and the planning submission where one is needed
- Structural calculations by a chartered engineer
- Groundworks, foundations and steelwork
- Brickwork, roofing and weatherproofing matched to the existing house
- First- and second-fix electrics and plumbing
- Plastering, decoration, flooring and tiling to the agreed specification
- Bi-fold or sliding doors, roof lights and glazing as specified
- Building Regulations inspections and the completion certificate
- Skip hire, scaffolding and site protection
- 12-month workmanship guarantee
What can change the price, and how we handle it
Only two things move a fixed price. The first is a change you ask for: a bigger roof light, a different kitchen layout, an extra socket run. Any change is priced and agreed in writing before the work is done, so there is never a surprise on the final invoice. The second is a finish you choose above the specification in the contract — porcelain instead of the tiles allowed for, say — and that is handled the same way, as a written variation you approve first.
What does not move the price is the ordinary business of building: weather, a wall that needs a bit more making good, a delivery that arrives late. Those are our problem, and they are why we survey before we quote rather than after.
How to compare extension quotes like for like
Most of the gap between two extension quotes is scope, not margin. Before you compare numbers, check that each one covers the same list. The cheapest quote is often the one that has quietly left something out.
- Is VAT included, and is it shown?
- Are drawings, the planning fee and the structural engineer inside the price or extra?
- Who pays Building Control fees, and who books the inspections?
- Are skips, scaffolding and site protection included?
- Is the specification written down — glazing, insulation, flooring, tiling allowances?
- Is it a fixed price or an estimate? Ask which word is in the contract.
- What guarantee is offered, and is it in writing?
- Is the quote itemised so you can see the split between structure, services and finishes?
How we deliver
From first visit to sign-off in 4 steps
Free site visit & brief
We meet at your home, listen to what you're trying to achieve and survey the existing structure. Typically within 5 working days of enquiry.
Design & fixed-price quote
We produce drawings, a written specification and a single fixed-price contract. No 'estimates' that drift upwards mid-build.
Build
One project manager owns delivery from groundworks to finishing. Weekly progress updates, photos and a clean, signed-in site.
Snag, sign-off & guarantee
Joint walk-around to clear any snags before we hand over. You leave with certificates, drawings and our 12-month workmanship guarantee.
Our work
Recent house extensions we've delivered
Where we build fixed-price extensions
Most of our extensions are within an hour of Birmingham. Each area page explains what the local housing stock and planning authority mean for your project.
Fixed-price extensions FAQs
Ready to start?
Get one price for the whole extension
Free site visit. Written fixed-price quote in 5–7 days. No obligation.