Trade Estimating
Extension estimates that cover every trade end to end
We price single and double storey extensions across all trades from your drawings so you can quote the whole job with confidence.
In short
An extension estimate prices the whole job: groundworks, structure, roof, windows, services and finishes across every trade.
We measure each element off your drawings, price the trades and bring them together with preliminaries into one estimate.
You get an itemised, branded estimate covering the full extension from foundations to final decoration.
Who it's for
Builders and main contractors pricing domestic extensions, and developers adding space to existing homes.
An extension is a complete small build, so the estimate has to carry every trade and the joins between them. Groundworks and foundations, brick and block superstructure, steel for the opening into the existing house, roof, windows and doors, first and second fix services, plastering and finishes all have to be measured and priced, and the connection to the existing building has to be thought through. We build the estimate trade by trade so nothing is missed and the totals add up to a real, deliverable job.
The link to the existing house is where extensions get under-priced. Knocking through usually needs a steel beam with padstones and temporary propping, the existing roof and walls need making good where the new structure meets them, and matching the existing brick, render and finishes can be slow and expensive. We price the structural opening, the making good and the matching, because these items sit between the trades and are exactly what gets forgotten.
Preliminaries and the things that are not bricks and mortar matter on an extension. Scaffolding, skips, welfare, the building control inspections, protecting the occupied house and working around the people living there all carry cost and time. We allow for the preliminaries and flag where party wall agreements, drainage build-overs or planning conditions add scope, so the price reflects the real job rather than just the visible building work.
What the estimate includes
What drives the cost
The numbers that move the price on a extensions job, and the detail we measure to get them right.
Size and number of storeys
Floor area and whether it is single or double storey drive the base cost, but a double storey adds structure, scaffold and a second floor of services and finishes.
The link to the existing house
The knock-through needs a steel beam, padstones and propping, plus making good where new meets old. This connection is a real cost that a new build avoids.
Matching existing finishes
Matching the existing brick, render, roof tiles and internal finishes can be slow and costly, especially where the original materials are no longer available.
Glazing and the roof
Large glazed openings, bi-folds, lanterns and flat or pitched roof choices change the cost considerably and are often where the client wants to spend.
Groundworks and drainage
Foundation depth, the ground conditions and any drainage that has to be diverted or built over add cost below ground before the visible work starts.
Working in an occupied home
Protecting the existing house, working around the occupants and phasing the work to keep the home usable all add time and care that an empty site does not.
Common pitfalls we help you avoid
- Pricing the new structure and forgetting the knock-through, steel and making good.
- Under-allowing the cost of matching existing brick, render and tiles.
- Missing the preliminaries: scaffold, skips, welfare and building control.
- Ignoring drainage build-overs or diversions under the extension.
- Forgetting the extra time of working around an occupied house.
How it works
Send us the extension drawings
Upload your plans, elevations and structural drawings, and tell us the specification and how it connects to the existing house.
We measure and price
We measure every element, price the trades, allow for the link to the existing building and add preliminaries.
You get a branded estimate
We return an itemised estimate under your own name, covering the full extension from foundations to final decoration.
Frequently Asked Questions
Got a job that needs pricing?
Upload your drawings and we'll come back with a professional, branded estimate, a fixed fee and a turnaround time.
Upload Your Drawings