What is Technical Due Diligence for Site Acquisition?
Technical due diligence, in terms of site acquisition, is a deep-dive assessment of a site’s physical, environmental and regulatory characteristics. You’ll do this before completing the purchase or getting too far into the planning process. Due diligence is all about gathering information. It helps you to really understand what you’re getting into, and what constraints, risks or hidden costs might be waiting down the line. Think of it as your insurance policy. It doesn’t get rid of the risks. But it means you’re aware of them and you’re less likely to get a nasty surprise. Like finding out that your ‘shovel-ready’ site has soil contamination, access issues and no viable utility connection.
Why Does it Matter?
When you’re acquiring a site for a new development, you’re making a decision based on potential. Whether you’re buying a residential, commercial, or mixed-use property, you get a blank canvas to work on. Often sold with glossy visuals and plenty of optimism!
But without proper due diligence, you’re essentially buying blind.
In fact, at Harrison Clarke we’ve seen cases where developers didn’t realise the site had a major underground easement for unidentified main gas pipes. This meant the team had to replan the layout, which increased costs to add a new capping detail over the pipe and caused significant delays. In another example, a developer bought a site known to have contamination, and planned for remediation. But they failed to appreciate the tidal nature of the water table, and local aquifer decontamination took another 3 months to complete, meaning higher clean up and construction costs. We’ve also been involved in developments at a later stage, and failure to undertake proper TDD failed to fully investigate the drainage potential for around 150 new homes. This led to long, drawn-out discussions about potential routes over neighbouring land to avoid having to spend over £1M on laying a new drain under an already busy main road.
So when we say it can and does happen, we know because we’ve seen it! Technical due diligence identifies these kinds of issues early, flagging them as potential risk.. It’s not just about whether you can build. But whether you can build what you want, within your budget and on time.
What’s Involved in Site Acquisition TDD?
That’s all well and good, but what does this process actually look like? When Harrison Clarke is brought in for a site acquisition technical due diligence, we’re looking at a wide range of factors that can affect development viability. This breaks down into 8 key areas:
Site Conditions and Ground Risk: This involves reviewing any existing surveys (if they’re available) or commissioning new ones. This could include phase 1 environmental assessments, flood risk assessments or ground investigations. We check for site contamination, analyse the soil profile, and investigate any history of mining. Or even if there’s a history of any archaeological issues on the site. These things all impact foundation design and cost, so they need to be factored in.
Access and Infrastructure: Can you actually get to the site legally and safely? Is there an adopted highway? What about transport links, footpath rights or way, or ransom strips? It’s amazing how many deals fall through over access, so it’s important to know from the start!
Utilities and Services: At this stage we check for any existing services, capacity and the availability of the connections. Electricity, gas, water, telecoms, foul and surface water drainage, all of these are important. Upgrading diversions can cause major hidden costs.
Planning Constraints and Designations: Here, we ask questions like, is the site within a flood zone? Is it protected greenfield, or in a conservation area? Are there any Tree Preservation Orders or archaeological sensitivities you need to be aware of? These factors determine what you can and can’t do on the site and may cause significant delays before starting any building work.
Legal and Title Issues: Working with your legal team, we help to review boundaries, easements, covenants and third-party rights. If someone else has rights to cross your site (or worse, block part of it), you need to know, and take advice on viable options moving forward.
Topography and Buildability: Now we’re getting technical! Does the site have a slope? Are there retaining walls, embankments or watercourses? Beyond that, how easy is it to actually build on this land? A site might look straightforward on paper, but be full of hidden engineering challenges when you look closer.
Existing Structures or Demolition: If there are already buildings on the site, they will need to be assessed for structural condition, hazardous materials and demolition complexity. These can impact costs and programming, since it’s common to find that certain types of structures can’t be demolished during certain nesting or migration periods.
Sustainability and Net-Zero Considerations: Increasingly, clients are looking for sites that can support low-carbon developments. For this we’ll look at orientation, infrastructure potential, biodiversity net gain requirements and potential sulphate/nitrate issues. This is especially important because of the recent changes to planning requirements.
When Should You Carry Out Site Acquisition Technical Due Diligence?
One of the most common questions we get asked is ‘when should we actually do the technical due diligence?’
The answer is – as soon as possible!
Ideally, you should be doing an initial technical due diligence before you even exchange contracts, even if it’s on a conditional basis. At the very least, you should have a solid technical review during the exclusivity or heads-of-terms stage. The earlier you can identify the risks, the more time you have to renegotiate terms, adjust your design, or walk away if necessary.
How to Get Site Technical Due Diligence Right
So the next question is, how do you get your technical due diligence right?
Start by involving the right people. You want someone who can coordinate a multi-disciplinary team and who understands development. Not just the building surveyor part, but the planners, engineers, environmental consultants and legal advisors, all feeding into one joined-up picture.
Second, be realistic. Technical due diligence isn’t about giving you the go-ahead or hitting the brakes. It’s about giving you the data you need to make an informed decision. And finally, make sure you budget for it. Yes, it adds another upfront cost to an expensive process.. But compared to the risk of spending hundreds of thousands – or even millions – on a site that you can’t use properly, it’s money well spent.
In other words, technical due diligence is all about risk management. It helps you to identify issues early, plan smarter, negotiate better and build with confidence. Whether you’re a seasoned developer or this is your first site purchase, you can’t put a price on that extra peace of mind. As always, if you need any help or advice on this, or any other topic, our team at Harrison Clarke are here to help. Just give us a call on 02381 550 051, and one of our team will be happy to chat.
For more expert advice on surveying and property matters, check out our range of informative videos on our website or YouTube channel. Harrison Clarke Chartered Surveyors is here to guide you every step of the way!
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