Not every planning application is worth your time. A firm that does £150k loft-and-rear extensions shouldn’t be chasing a £20k garden-room certificate, and a kitchen specialist shouldn’t be cold-emailing a demolition-and-rebuild. The good news: you can size a job surprisingly well straight from the application itself, before you speak to a soul. Here are the shortcuts a quantity surveyor uses to read the value out of the proposal.

Why triage matters

Outreach has a cost — your time, and your reputation if you pitch the wrong thing. Ten well-judged approaches to projects that fit your firm beat a hundred scattered ones. Estimating build value up front is how you filter the firehose of new applications down to the handful that are actually yours.

Start with the application type

The application type is the fastest single signal of scale:

Householder — extensions, loft conversions, garages, on a single home. Typically £20k–£250k of work.
Full — anything from a new dwelling to a commercial scheme. Hugely variable; read the description.
Outline — establishing the principle of development before the detail. A signal of bigger work coming, but not imminent.
Listed Building Consent — heritage work, specialist trades, higher rates.
Change of Use — often a fit-out or conversion; e.g. office-to-resi can be a substantial refurbishment.
Reserved Matters — the detail following an outline approval; the build is now real and near.

Read the proposal description

The free-text proposal is where the money is described. Learn to read the verbs and the dimensions. “Single-storey rear extension” is a different animal from “demolition of existing dwelling and erection of two replacement dwellings.” Watch for:

Storeys and footprint — “two-storey side and rear extension” roughly doubles a single-storey job.
Demolition — “demolish and rebuild” means a near-new-build budget, not an extension one.
Basements — “excavation to form basement” is one of the most expensive things on the list per square metre.
Number of units — “erection of 4 dwellings” multiplies everything.
Glazing and structure — “glazed link,” “structural opening,” “steel frame” all push the rate up.

Rough cost rates that get you close

These are ballpark UK figures for triage only — not a quote, and they move with region and spec — but they get you to the right order of magnitude:

Standard rear/side extension: roughly £2,500–£3,500 per m² of new floor.
Loft conversion: roughly £40k–£70k for a typical dormer with an en-suite.
Basement (new dig): often £4,000–£6,000+ per m² — the premium job.
New-build house: commonly £2,000–£3,000+ per m² of gross internal area, plus externals.
Refurbishment / fit-out: hugely spec-dependent, but £1,000–£2,500 per m² is a working range.

So a “40 m² two-storey rear extension” at ~£3,000/m² points to roughly £120k of construction. That’s enough to know instantly whether it’s a fit for your firm.

Using floor area and property value

Two extra data points sharpen the estimate enormously. The EPC floor area tells you the size of the existing building, which anchors the scale of any extension or refurbishment. And the property’s value tells you the owner’s likely budget headroom — people rarely spend on works that would push a home far beyond the ceiling price for its street. A £2m house can justify a £300k basement; a £350k terrace usually can’t.

Read together — application type, proposal text, floor area, value — you can sort a week’s applications into “mine,” “too small,” and “too big” in a couple of minutes each.

Flags that change the number

Conservation area or listed pushes rates up and brings in specialist trades and materials. Sloping or constrained sites add groundworks and access cost. Party wall situations on terraces add time and risk. None of these are deal-breakers — for the right firm they’re the reason the margin is better — but they change the figure and the kind of contractor that suits.

The honest summary

You don’t need a site visit to know whether a job is worth chasing. Application type sets the scale, the proposal text describes the work, a per-m² rate gets you to a rough build value, and floor area plus property value tell you whether the budget is really there. Get quick at this and your outreach gets ruthlessly well-targeted. House of Planning Service puts the application type, proposal, EPC floor area and an indicative value side by side on every lead — and lets you filter by value and rating — so the triage is mostly done before you start.

How to estimate build value from a planning application