Is Labour Really 35% to 45% of an Extension Budget?

When considering a home extension, one of the most common figures you'll hear bandied about is that labour accounts for around 35% to 45% of your total budget. But how accurate is this claim in today's market, especially when factoring in regional variances like the Birmingham versus London rates, the impact of day rates, and the ongoing house price dynamics impacting places like Solihull? In this post, we’ll break down the numbers, sanity-check costs per square metre, and explain what you need to know before budgeting for your extension.

The Solihull Price Gap is Driving 'Extend-Not-Move' Decisions

Recent data clearly shows why many homeowners around Solihull are choosing to extend rather than move. According to the Office for National Statistics (ONS), the local house price breakdowns from May 2026 reveal a significant price gap between Solihull and Birmingham, let alone London.

Simply Visit this site put, larger detached homes in Solihull command premium prices, and with rising stamp duty and other moving fees, extending your current property is increasingly a more cost-effective option. But how does labour factor into these extension budgets?

Labour Share: What Does 35% to 45% Actually Mean?

The oft-quoted “labour accounts for 35% to 45% of the extension cost” is a useful rule of thumb, but as someone who's spent over a decade pricing UK extensions, I always sanity-check what that means in practice. Labour costs include all paid tradespeople—from bricklayers and joiners to electricians and plumbers.

To illustrate this properly, let's first look at the standard breakdown of an extension budget:

• Labour (Trades): 35% to 45%
• Materials: 40% to 50%
• Professional fees (architects, engineers): 5% to 10%
• Other costs (contingency, VAT, planning fees): approx 5% to 10%

What trips people up is the variance based on the type and size of their extension, and the location.

Extension Costs by Size and Type

From my experience analysing projects via quotes from platforms like Checkatrade and MyJobQuote, costs per square metre increase with complexity:

Extension Type Approx. Cost per sqm (£) Labour Share (%) Notes Single-storey rear extension £1,500 – £2,200 35% – 40% Basic foundation, walls, roof - moderate labour Two-storey side/rear extension £2,000 – £3,200 40% – 45% More structural work; increased labour (scaffolding, complex roofing) Loft or garage conversion (not garden extension) £1,800 – £2,500 40% – 45% Specialist trades needed; labour rates higher

In two-storey extensions, labour intensity increases because of scaffolding, structural steelwork, and working at height risks, pushing the share closer to 45%. Smaller or single-storey builds often sit at 35% to 40%, reflecting simpler tasks.

Regional Labour Day Rates: Birmingham vs London

Labour day rates greatly impact the overall budget and can explain the deviance in labour share across Britain. London tradespeople command some of the highest rates—due to higher living costs, site constraints, and demand—often charging 20%-30% more than their Birmingham counterparts.

To put this into perspective:

• Birmingham carpenter or bricklayer day rate: approx. £180 - £220 (including VAT)
• London counterpart day rate: £240 - £300+

This markup inflates the labour share of London builds, pushing closer to or even slightly above 45%, while in Birmingham and Solihull, a typical labour share hovers between 35% and 40%.

The Day Rate Impact on Your Budget

Because labour often comes billed on a day-rate basis, delays or changes can rapidly cause overruns. Quality builders often quote their day rate clearly—something to check on estimates—especially since VAT inclusion can cause confusion.

Moving Costs That Add No Space

One of the reasons Solihull homeowners prefer extending is the heavy hidden costs in moving that add no usable space—that is, you don’t gain any square metres by paying them:

• Stamp Duty Land Tax (SDLT): Can run into thousands, especially on properties over £250,000.
• Estate agent fees: Typically 1.5% to 3% of the property sale price.
• Solicitor/legal fees: £800 - £1,500 depending on complexity.
• Survey and mortgage arrangement fees: Generally £300 - £700.

Because these moving costs add no space or value directly, but do represent a sizeable upfront investment, they further push families towards extending rather than moving, particularly in areas like Solihull where the price gap versus Birmingham and London has opened up significantly.

Planning Concerns: What People Forget to Budget For

Too many budgets ignore the crucial impact of planning and permit issues, especially in conservation areas or where permitted development rights are limited. Tools like the Solihull Council pre-application enquiry service are invaluable to get early feedback on your project’s feasibility.

Here are key points many homeowners forget to budget for:

• Planning application fees: Range from £206 to £462 depending on the size/type.
• Architect or planning consultant fees: May add 5% to 10% of your build cost.
• Potential delays caused by planning refusals or conditions.
• Enhanced insulation or window restrictions in conservation areas.

Using the Planning Application and Permitted Development checks before committing helps avoid nasty surprises and budget blowouts.

Final Thoughts: What You Should Really Expect for Labour Costs

If you’re considering an extension, here’s a quick checklist to sanity-check your labour budget:

1. Check whether the quotes include VAT. Confusion on this can add 20% extra.
2. Get day rates clearly stated. If a quote lumps labour into a lump sum without details, be wary.
3. Factor in contingency—at least 10% of labour costs. Delays and changes cost money.
4. Understand your location’s impact. Labour in London vs Birmingham differs significantly.
5. Remember two-storey extensions attract higher labour cost shares than single-storey.
6. Use local authority tools. Solihull Council’s pre-application enquiry and planning checks are must-dos.

Labour typically will form around 35% to 45% of your budget, but it’s essential this figure is based on clear day rates, realistic build complexity, and regional market conditions.

By arming yourself with current benchmarks from trusted sources like the ONS, quotes from verified trades on Checkatrade, and real project listings from MyJobQuote, you’ll stand a far better chance of holding your builder’s feet to the fire and sticking to a sensible extension budget.