How We Priced a 10-Plot New Build Development (And What It Cost)

The Brief: A 3-Bedroom Detached New Build

Plot 6 was a traditional 3-bedroom, 2-storey detached dwelling — cavity wall construction, concrete tile roof, standard UK planning envelope. Nothing exotic. But that’s kind of the point.

Most builders think “straightforward” jobs don’t need a proper QS. They do. Especially when you’re replicating across 10 plots — because a £5,000 error per unit compounds into a £50,000 overrun before a single roof tile goes on.

Here’s what we were working with:

Gross Floor Area: ~115m² (internal)
Plot Type: Detached, 2-storey
Structure: Traditional masonry cavity wall — facing brick outer leaf, insulated cavity, dense block inner leaf
Foundations: Strip foundations (assumed good ground), 600mm wide × 1000mm deep, C25/30 concrete
Roof: Pitched roof, concrete interlocking tiles on treated softwood rafters/purlins
Windows & Doors: uPVC double-glazed throughout, composite front door
Heating: Gas combi boiler, underfloor heating to ground floor, rads to first floor
Finishes: Plasterboard + skim throughout, carpet to bedrooms, LVT to kitchen/living/bathroom areas

Standard spec. Replicable. Exactly why it needed to be priced precisely — because on a 10-unit development, your template cost plan is your business case.

How We Structured the QS Report

At RapidQS, every new build cost plan follows the same structure — no matter the size. Here’s the breakdown we used for Plot 6:

1. Preliminaries

This is the stuff most builders forget to price properly and then wonder where their profit went.

Site management & supervision
Scaffold (erect, hire, dismantle)
Welfare facilities
Skip hire & waste disposal
Plant & equipment hire
Building control fees
Structural engineer fees (PS)

Typical prelims range for a 3-bed new build: £12,000–£18,000 depending on programme length and site conditions.

For Plot 6, we allowed 10 weeks on site. That’s realistic for a well-managed, trade-sequenced single plot. On a 10-plot scheme running sequentially with shared prelims, you can drive this cost down significantly — which is exactly what we modelled across the full development.

2. Substructure

Foundations are where ground conditions bite you. We always note our assumptions clearly:

Strip foundations C25/30 concrete — 600×1000mm
Hardcore Type 1 MOT blinding — 150mm compacted
1200-gauge polythene DPM
100mm PIR rigid insulation (Kingspan/Celotex)
A142 mesh reinforcement
Ground bearing slab C25 — 100mm
Sand/cement screed — 65mm power-floated

Estimated substructure cost (Plot 6): £18,500–£22,000 ex. VAT

Ground conditions are always a risk. We included a provisional sum for any soft spots or drainage diversions — because assuming perfect ground on a greenfield plot is how developers go broke.

3. Superstructure — Walls, Floors & Roof

This is the heart of the build and usually the biggest variable between a tight QS and a loose one.

External walls:

Facing brick outer leaf — ~£3.20/nr (London & SE fringe market rate)
100mm insulated cavity (Rockwool or PIR bead)
Dense concrete block inner leaf
Stainless steel wall ties, DPC, cavity closers

First floor:

200×50 C24 joists @ 400 c/c
22mm tongue-and-groove chipboard deck

Roof structure:

Prefabricated trussed rafters (standard pitch)
Roofing felt + treated batten
Concrete interlocking tiles
UPVC guttering, fascia, soffit

Estimated superstructure (walls, floors, roof): £42,000–£52,000 ex. VAT

The range matters. Brick prices in the South East are running 15–20% higher than the Midlands right now. If you’re using a national rate book and building in Surrey, you’re already behind.

4. Internal Fit-Out

This is where specifications vary the most between developers — and where the biggest margin opportunities hide.

For Plot 6 we priced to a mid-market spec:

Plasterboard + skim all walls and ceilings
Joinery: skirting, architrave, internal doors (FD30 to kitchen)
Kitchen: provisional sum (client to specify, typical £6,500–£9,000 supply-only)
Bathrooms: full en-suite + family bathroom (sanitary ware, tiling, plumbing)
Staircase: softwood closed-tread with painted balustrading
Painting & decorating: full two-coat throughout

Estimated internal fit-out: £28,000–£35,000 ex. VAT

5. Mechanical & Electrical

M&E is chronically under-priced on new builds. Here’s what a proper allowance looks like:

First fix electrical throughout (consumer unit, circuits, earthing)
Second fix (sockets, switches, light fittings allowance)
Gas combi boiler supply + installation
Underfloor heating (ground floor) — manifold, pipe, control
Radiators + TRVs (first floor)
Bathroom extract fans, MVHR if required by spec
Solar PV — provisional sum (increasingly required under Part L)

Estimated M&E: £22,000–£28,000 ex. VAT

Don’t cut M&E. It’s the one trade that causes the most defects, the most snagging, and the most arguments at handover.

6. External Works

Often completely omitted from builder quotes. Never acceptable on a new build.

Driveway (block paving or tarmac allowance)
Boundary fencing
Topsoil reinstatement to garden areas
Utility connections (electric, gas, water, drainage) — provisional sums
Adoptable drainage if applicable

Estimated externals: £8,000–£14,000 ex. VAT

Utility connections alone can swing by £5,000 depending on proximity to mains. Always provisional sum and always confirm with the utility providers early.

Total Build Cost — Plot 6

Element	Cost Range (ex. VAT)
Preliminaries	£12,000 – £18,000
Substructure	£18,500 – £22,000
Superstructure	£42,000 – £52,000
Internal Fit-Out	£28,000 – £35,000
M&E	£22,000 – £28,000
External Works	£8,000 – £14,000
Total	£130,500 – £169,000
Cost per m²	~£1,135 – £1,470/m²

That’s a realistic mid-spec new build cost for the South East in 2026. Anyone quoting you below £1,100/m² for this spec is either cutting corners or hasn’t priced it properly.

Why We’re Pricing All 10 Plots

When the client told us they were building 10 of these, the first thing I said was: “Good. That’s where the real savings are.”

Here’s why repeat-unit pricing matters:

1. Shared Prelims Drive the Cost Down

On a 10-plot scheme running in sequence, you’re not hiring scaffolding 10 times. You’re stripping it from Plot 1 and moving it to Plot 2. Site management, welfare, plant hire — all of it gets amortised across the development. On a well-run scheme, prelims per plot can drop by 30–40% versus a standalone build.

2. Bulk Purchasing Power

When you’re ordering bricks for 10 houses at once, you have buying power. A good procurement strategy on a scheme like this can shave 8–12% off materials costs alone.

3. Trade Continuity = No Remobilisation Costs

Your bricklayer, your roofer, your electrician — they price in risk when they don’t know if there’s more work coming. Lock them in across 10 plots and their rates reflect that certainty. Every trade we spoke to on this project dropped their rate when they heard the full scope.

4. Learning Curve Savings

Plots 1 and 2 will always be slower. By Plot 5, the team knows the build inside out. By Plot 10, they’re delivering it faster than anyone could have tendered. You can’t capture that value without proper cost tracking across the scheme — which starts with a QS.

For this client, we estimated total savings across the 10 plots of approximately £180,000–£240,000 versus pricing each plot in isolation. That’s not a rounding error. That’s a profit centre.

What a QS Report Actually Does for a Developer

Let me be direct about this, because I talk to builders every week who think a QS report is just a number on a spreadsheet.

It isn’t.

A proper QS report is a risk management document. It tells you:

Where your cost exposure is (ground conditions, M&E, procurement)
What’s provisional and what’s fixed
What assumptions have been made and where they could be wrong
How your costs compare to market benchmarks
What your contingency should be (and why)

On a 10-plot development, your QS report is also your bank document. Lenders want to see a credible cost plan before they release development finance. A RapidQS report is formatted to satisfy that requirement from day one.

Are You Building Something Similar?

If you’re a UK developer or builder with a new build scheme — whether it’s 1 plot or 100 — and you need a cost plan that’s actually built on real numbers, we’d love to talk.

We price new builds across the UK. We understand regional cost variances, current material prices, and what the trades are actually charging right now — not what a rate book from 2022 says they should charge.

We typically turn around a new build QS within 5–7 working days.

👉 Get a Quote from RapidQS

Or send your drawings directly to info@rapidqs.uk and we’ll come back to you within 24 hours with a fee proposal.

RapidQS provides professional quantity surveying services for residential and commercial projects across the UK. All estimates in this article are indicative and based on current market conditions. Contact us for a project-specific cost plan.