How much does a single-storey extension cost?

Most UK single-storey extensions work out around £1,800 per m² for a standard specification, so a 30m² extension lands near £54,000 before fit-out. Mid-range spec adds around 20% and high-end around 45%.

Why price by floor area rather than a flat figure?

Floor area is the only input that scales honestly. A 20m² and a 45m² extension are the same job description and very different builds, so pricing per m² keeps the estimate defensible.

What is not included in a build quote?

Structural calculations, electrics, plumbing and heating, plastering and decorating, kitchen or bathroom fit-out and making good are all priced separately here, because whether they are in scope varies enormously between jobs.

Should I ask when the customer wants to start?

Yes. Timescale is the single best qualifying question on a big-ticket build. Someone starting within a month and someone just exploring need very different follow-up, and knowing which is which saves you site visits.

Is there a downloadable builder & extensions quote template?

Yes. As well as the free online version, you can buy the builder & extensions quote pack as a spreadsheet for £7. It opens in Excel, Google Sheets or Apple Numbers, with the pricing maths already built in and a branded quote you can export to PDF. Buy once and it's yours to keep.

Builder & Extensions quote template

Name: Builder & Extensions quote template
Brand: Quotify
Availability: InStock

Estimate extensions and conversions by project, floor area and spec, with trades and finishing extras.

Use this template I already have an account

Home Services· 5 questions· area (m²) + options· Instant quote

Just want the spreadsheet? £7 Excel with the pricing built in, plus a printable PDF. No account needed.

The actual form ↓ LIVE DEMO

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Nothing's submitted — pricing recalculates on every answer, exactly as a customer would see it. Open full screen →

Start from this template ✦ Customise it to your pricing ✦ Conditional logic built in ✦ Instant customer quotes ✦ Embed on any website ✦ Capture every lead ✦ No code required ✦ Live in minutes ✦

01 5 questions pre-built

02 Real-time pricing logic

03 Customer-facing PDF estimate

04 Instant email notifications

05 Fully customisable pricing

About this template

Nobody wins a build job by being vague. A clear per-m² estimate with the trades listed puts you ahead of every builder who said they would come back with a figure and didn’t.

Extensions and conversions live or die on scope. This template prices by project type and floor area in m², then layers on specification level and which trades you are carrying, so the number reflects the actual build rather than a guess.

Who it's for

Builders, main contractors and design-and-build firms quoting extensions, loft and garage conversions, internal remodels and new builds.

What the form asks

5 questions by default, branching where the job needs it. Extend with any of Quotify's supported question types .

Q1 Choice

Project type Single-storey extension · Double-storey extension · Loft conversion · Garage conversion · Internal remodel · +1 more

Q2 Area

Floor area m²

Q3 Choice

Specification level Standard · Mid-range · High-end

Q4 Multi-select

Include these trades? Structural calculations · Electrics · Plumbing & heating · Plastering & decorating · Kitchen / bathroom fit-out · +1 more

Q5 Choice

When would you like to start? Within 1 month · 1–3 months · 3–6 months · Just exploring

Make it yours in three moves

01 Set your prices Plug in your own per-job fixed prices and hourly rate, so the numbers are yours from the first enquiry.

02 Add your uplifts Callout fees, urgency multipliers and any add-on or parts pricing, layered on top of your base rates.

03 Put it to work Embed it on your website or share a direct link in listings, local groups and DMs.

Not quite your trade? Describe your business and Quotify builds you a form from scratch.

Use this template Free to start · no card needed

Your questions, answered

Last updated 5 August 2026

01 How much does a single-storey extension cost?

Most UK single-storey extensions work out around £1,800 per m² for a standard specification, so a 30m² extension lands near £54,000 before fit-out. Mid-range spec adds around 20% and high-end around 45%.
02 Why price by floor area rather than a flat figure?

Floor area is the only input that scales honestly. A 20m² and a 45m² extension are the same job description and very different builds, so pricing per m² keeps the estimate defensible.
03 What is not included in a build quote?

Structural calculations, electrics, plumbing and heating, plastering and decorating, kitchen or bathroom fit-out and making good are all priced separately here, because whether they are in scope varies enormously between jobs.
04 Should I ask when the customer wants to start?

Yes. Timescale is the single best qualifying question on a big-ticket build. Someone starting within a month and someone just exploring need very different follow-up, and knowing which is which saves you site visits.
05 Is there a downloadable builder & extensions quote template?

Yes. As well as the free online version, you can buy the builder & extensions quote pack as a spreadsheet for £7. It opens in Excel, Google Sheets or Apple Numbers, with the pricing maths already built in and a branded quote you can export to PDF. Buy once and it's yours to keep.

Start from our Builder & Extensions template.

14-day free trial. No card required.

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