ePrivacy and GPDR Cookie Consent by Cookie Consent The pitfalls of 'design and build' companies

The pitfalls of 'design and build' companies

5 min read
Oct '25 • by Heather

Quick summary

Using a design and build company can lead to hidden costs, limited choice, and lower design quality. They often quote based on standard designs and best-case scenarios, risking budget blowouts and uninspired results. For a typical extension, expect to pay from around £1,500 to £3,000 per square metre, but beware of extra charges for changes or complex projects.

If you’re pursuing an extension or conversion, you’re probably considering a range of companies for your project. Perhaps some of them are architecture practices (ahem) but others might be what’s known as ‘design and build’ companies.

At Resi, we’ve met many homeowners who have gone with a design and build, and while some of those projects worked out, some suffered the hidden consequences of this industry. After all, while architects design to maximise the space and well-being of the homeowner, someone in the construction will be designing to maximise on ease of build and profits - creating a conflict of interest. Those who use them can not only potentially face poor design and dodgy construction, they might also be hit by some nasty budget blows.

To understand why caution should be exercised, here are some of the common pitfalls to using a ‘design and build’...

Misleading prices

One of the reasons design and builds are so tempting is the upfront costings.

Whether you go for an extension, conversion, or even renovation, it’s easy to get overwhelmed by all the different processes, professionals, and prices you’re faced with. So why wouldn’t you be woo’ed by someone providing one simple price for the whole lot?

How much does an architect charge?