How much does it really cost to build a house in the UK?

It sounds like a straightforward question. You might expect to find a standard cost-per-square-metre figure, multiply it by the size of the proposed property and arrive at your answer.

Unfortunately, property development isn't quite that simple.

The cost of building a house can vary considerably depending on labour rates, material prices, plant costs, location, design, specification and the individual conditions of the development site.

More importantly, if you're assessing land for property development, build cost is only one part of the calculation.

The question you really need to answer is:

Does this development stack up financially, and what is the maximum I can afford to pay for the land?

Let's look at how you can work that out.

Why Cost Per Square Metre Isn't Enough

A cost-per-square-metre figure can be useful for an initial estimate, but relying on it alone can be dangerous.

Two houses with exactly the same floor area could have very different construction costs.

Why?

Because your actual build cost can be affected by:

• Local labour rates

• Material prices

• Plant and machinery requirements

• The design and complexity of the property

• The level of specification

• Ground and site conditions

• Access to the site

• Drainage and services

• Location

• Individual construction methods

That's why developers need to go beyond a headline figure and understand what is actually involved in constructing the proposed development.

Start With the Gross Development Value

Before becoming too focused on what the development will cost to build, you need to understand what the finished development could be worth.

This is your Gross Development Value (GDV).

GDV is essentially the estimated total value of your completed development.

For example, if you plan to build four houses and each finished property is expected to sell for £400,000, the potential GDV would be:

4 × £400,000 = £1,600,000 GDV

But that doesn't mean you can simply subtract the construction costs and spend whatever remains on the land.

There are many other costs and allowances to consider.

Work Backwards From GDV to Calculate Land Value

One of the most important disciplines in property development is learning to work backwards from the end value.

Rather than starting with the landowner's asking price and trying to make the development fit around it, start with the GDV and deduct the costs required to deliver the project.

These may include:

GDV
– Target development profit
– Build costs
– Professional fees
– Planning and statutory costs
– Finance costs
– Sales and marketing costs
– Other development costs
= Indicative land value

This approach gives you a much clearer indication of what the site may actually be worth to you as a developer.

The landowner may want £500,000.

Your appraisal might tell you the maximum you can afford to pay is £300,000.

If that's the case, paying £500,000 simply because that's the asking price could remove your profit before you've even started building.

Don't Forget Your Development Profit

A development project isn't viable simply because the sales revenue is greater than the construction costs.

You need to allow for a suitable development profit.

You're taking on considerable risk throughout the development process, including planning risk, construction risk, finance risk, market risk and sales risk.

Your target profit therefore needs to be included in the appraisal before determining how much you can afford to pay for the land.

If the numbers don't leave sufficient room for your required return, you may need to renegotiate the land price, redesign the scheme, find efficiencies or walk away from the opportunity.

And sometimes, walking away is the most profitable decision you can make.

Build Costs vs Development Costs

Another important distinction is the difference between build costs and development costs.

Your build costs relate primarily to physically constructing the properties.

These can include:

• Groundworks

• Foundations

• Drainage

• Superstructure

• Roofing

• Windows and doors

• First-fix services

• Plastering

• Kitchens

• Bathrooms

• Second-fix work

• Decoration

• External works

• Labour

• Materials

• Plant

But these aren't your only expenses.

A property development project can also involve costs for architects, planning consultants, engineers, surveys, building control, warranties, finance, legal work, utilities, marketing and selling the completed properties.

Looking only at the physical construction cost can therefore give you a misleading picture of the project's profitability.

Break the Development Into Individual Construction Stages

Instead of relying entirely on one overall square-metre rate, I prefer to break the development into its individual construction stages.

This is where a detailed Build Cost Model becomes valuable.

You can examine each stage and identify the resources required.

For example:

Labour: How many people will be required and for how long?

Materials: What quantities are needed and what will they realistically cost?

Plant: What machinery or equipment will be required?

By building the estimate from the individual components, you gain a much clearer understanding of where your money is going.

It also makes it easier to update the model when prices change.

Use Local Cost Information

Construction costs aren't identical throughout the UK.

Labour might cost significantly more in one location than another. The same can apply to materials, subcontractors, transportation and plant.

That's why it's important to localise your cost data.

Research what tradespeople are actually charging in the area where you're planning to develop.

Speak to suppliers.

Check material prices.

Understand subcontractor rates.

Look at transportation and plant costs.

The more accurate your local information becomes, the more useful your development appraisal will be.

Specification Can Dramatically Change Your Build Cost

Specification is another factor that can quickly alter your numbers.

A house built to a relatively standard specification will have a very different cost profile from a high-end property with premium kitchens, bathrooms, flooring, glazing and finishes.

The intended selling price and target market should influence your specification.

You don't necessarily want to build the cheapest house possible.

But you also don't want to spend money on features that won't increase the property's value sufficiently to justify the additional cost.

Your specification needs to make sense for the local market.

Site Conditions Can Change Everything

Even if you understand your construction costs, the site itself can introduce significant additional expenditure.

Potential issues could include:

• Poor ground conditions

• Sloping land

• Difficult access

• Retaining structures

• Drainage requirements

• Utility connections

• Contamination

• Demolition

• Trees

• Ecology constraints

• Abnormal foundations

This is why two apparently similar developments can have completely different cost structures.

The property design matters.

But the land underneath it matters too.

Start With a Desktop Appraisal

You don't necessarily want to spend thousands of pounds on professional reports every time you discover a potential development site.

That's why an initial desktop appraisal can be so valuable.

Before committing significant money, investigate the fundamentals.

Ask yourself:

What could potentially be built here?

What would those properties be worth when completed?

What are my likely construction and development costs?

What profit do I require?

What does that leave for the land?

If the project doesn't work at this early stage, you may decide not to pursue it further.

If it does work, you can then move into more detailed investigations and professional due diligence.

The Three Stages of Development Appraisal

Your appraisal should become more accurate as the project progresses.

You can think of this in three broad stages.

Stage 1 – Initial Desktop Appraisal

This is your early assessment using the information available to determine whether the opportunity deserves further investigation.

Stage 2 – Detailed Viability Assessment

As you gather more information, you can replace assumptions with increasingly accurate figures.

This could include better build-cost information, professional advice, planning information and more detailed site investigations.

Stage 3 – Ongoing Cost Management

Once you're progressing with the development, your numbers shouldn't simply disappear into a spreadsheet.

Actual costs need to be compared with your estimates throughout the project.

If something changes, you need to understand how that affects your overall profitability.

Avoid Overpaying for Development Land

One of the biggest mistakes an aspiring developer can make is becoming emotionally attached to a site.

You find a piece of land.

You can picture the houses.

You start imagining the finished development.

Then you convince yourself that paying a little more for the land won't matter.

It does.

Your profit can be won or lost when you buy the land.

That's why your appraisal needs to determine your maximum land value before you commit yourself to the deal.

Don't make the numbers fit the asking price.

Make the land price fit the numbers.

So, How Much Does It Cost to Build a House?

There isn't one number that answers that question accurately for every property development.

The real answer depends on:

• What you're building

• Where you're building it

• How you're building it

• The specification

• Local labour and material prices

• The condition of the site

• The wider development costs

That's why successful property development isn't simply about knowing a cost-per-square-metre figure.

It's about understanding the entire financial picture.

Calculate your GDV.

Understand your build and development costs.

Allow for your required profit.

Then work backwards to establish what you can afford to pay for the land.

Ultimately, the most important question isn't:

“How much will this house cost me to build?”

It's:

“Does this development stack up, and what is the maximum I can afford to pay for the land?”

Getting that answer right before committing to a site can save you from making a very expensive mistake.