Do You Need a RICS Knotweed Survey?

That awkward moment usually happens mid-transaction. The buyer’s survey flags “possible Japanese knotweed” near the boundary, the lender asks questions, and suddenly everyone is waiting for someone to produce paperwork that actually answers them.

If you are trying to understand the Japanese knotweed RICS survey requirement, the first thing to know is this: there is not one single “RICS requirement” that applies to every property, every lender, and every situation. What exists is a professional expectation that suspected knotweed is assessed properly, recorded clearly, and managed with a plan that reduces risk to the building and the lender. In practice, that often means an invasive weed survey with a formal written report, evidence, and - where knotweed is present - a structured management and guarantee route that conveyancers and mortgage teams are comfortable with.

What people mean by the “RICS survey requirement”

RICS is a professional body that sets standards for surveyors. When a surveyor inspects a property and sees signs consistent with Japanese knotweed - or cannot rule it out - they are expected to record it, grade the risk, and recommend appropriate next steps.

For you as an owner, buyer, landlord, or property manager, that “next step” is usually the same: get a specialist to confirm whether it is knotweed, map it, measure it, and state clearly what it means for the property. Most general survey reports are not designed to do that in enough detail. They are there to flag concerns, not to manage them.

So, the reality is less about a single mandatory document and more about satisfying the chain of decision-makers: surveyor, lender, insurer, conveyancer, buyer and seller. When knotweed is involved, those people want clarity, not guesses.

When a RICS survey triggers further action

You tend to need a specialist knotweed report in three common scenarios.

First, when the property survey explicitly mentions Japanese knotweed or “invasive plant suspected”. Even cautious wording can be enough for a lender to pause.

Second, when knotweed is known locally - along a railway line, river corridor, unmanaged land, or a neighbouring plot - and the buyer asks for reassurance.

Third, when you are selling and you want to prevent last-minute renegotiation. If you can produce a clear report early, you remove uncertainty before it turns into delay.

There is a trade-off here. Ordering a survey proactively costs money, but it can protect you from bigger costs caused by stalled transactions, price reductions, or having to rush treatment decisions under pressure.

What “acceptable evidence” looks like to lenders and conveyancers

Mortgage teams and solicitors are not looking for botanical theory. They want documentation that is specific to the site and strong enough to base a decision on.

A useful knotweed report typically includes measured observations (how much, where it is, and how close it is to structures), clear mapping, and photographic evidence that shows context - not just close-ups of stems. If there is no knotweed present, it should say so plainly and show where and how the inspection was carried out, including boundary lines and adjacent land that can be viewed.

If knotweed is present, it is not enough to say “treat it”. The paperwork usually needs to show a structured management approach with timescales, method, and ongoing monitoring. Many lenders also want to see that treatment comes with a meaningful guarantee and that the provider is set up to stand behind the plan.

Why general surveys often cannot close the loop

It is understandable to assume a building survey should be able to confirm knotweed. In reality, general surveyors are not invasive plant specialists, may not have the time to inspect every boundary in detail, and may be visiting when growth is limited. They also cannot dig, disturb soil, or spend an hour tracking rhizome indicators across multiple gardens.

This is why you often see survey wording like “possible Japanese knotweed - recommend specialist assessment”. That line is doing its job: it flags risk without overstating certainty.

The problem is what happens next. If you do not move quickly, everyone else waits. The buyer worries. The seller feels accused. The lender hesitates. A fast, formal survey report is usually the quickest way to bring the transaction back under control.

What a specialist survey should cover (and what gets missed)

Japanese knotweed rarely behaves neatly within a single lawn or bed. It appears in corners, behind sheds, along fences, and through broken paving. It can also be present next door and still affect your sale if it is close enough to be considered a risk.

A proper on-site survey should look at the whole picture: the main garden, planting beds, boundary lines, and neighbouring fence lines that are visible. It should record the extent of growth, the density, and any indicators of historic cutting or disturbance.

Seasonality matters too. In winter, the plant dies back and you may be left with brittle canes or nothing obvious at all. That does not mean the issue has gone. A competent surveyor will know what signs to look for beyond fresh green growth and will document the limitations of visibility where relevant.

Does knotweed always stop a mortgage?

No. Knotweed is a risk, not an automatic deal-breaker. What tends to cause problems is uncertainty.

Where knotweed is confirmed and managed properly, many lenders are prepared to proceed, provided there is a credible treatment plan and a guarantee that reduces future liability. Where knotweed is only suspected and no one takes ownership of the next step, transactions can stall.

It also depends on proximity to the building and the practical likelihood of structural impact. A small, isolated stand at the far end of a large garden is a different scenario to dense growth against a boundary wall or near drains and hardstanding. The point of a specialist report is to replace vague concern with measured facts.

If you are buying: how to protect yourself without overreacting

If the survey raises knotweed, your job is not to panic or to demand unrealistic solutions. Your job is to insist on clarity.

Ask for a specialist survey and report that confirms presence or absence, shows the extent and location, and sets out a management approach if needed. If knotweed is present, you can then negotiate sensibly: treatment plan in place before completion, an agreed retention, or a price adjustment that reflects real costs rather than fear.

The worst outcome for buyers is exchanging on assumption. The second worst is pulling out when the issue could have been managed with the right documentation.

If you are selling: why speed and paperwork matter

Sellers often lose weeks because they wait for the buyer’s survey before doing anything. If knotweed is even a possibility - historic growth, neighbours with an issue, or a patch you have cut back - you are usually better off acting early.

A fast survey and clear report can prevent repeated site visits, reduce the scope for arguments, and keep your buyer focused on solutions rather than suspicion. It also helps your estate agent and solicitor respond quickly when enquiries land.

If treatment is required, starting sooner helps in two ways. It demonstrates responsible management, and it brings you closer to the point where a longer-term plan and guarantee can be presented as a risk control measure rather than a reaction.

What you should expect from a mortgage-ready knotweed survey

A mortgage-ready report is not about fancy language. It is about evidence and process.

At a minimum, you want a written report that is property-specific, supported by clear photos and mapping, and based on measured site observations. You also want turnaround that matches the urgency of a live transaction.

For many south of England owners, the simplest route is to book a defined survey product that delivers formal documentation quickly, then move straight into a structured treatment plan if knotweed is confirmed. For example, Japanese Knotweed Group Ltd provides an on-site survey from £250 + VAT with a detailed written report, 20 photographs, mapping, and measured observations covering gardens, beds, boundary lines, and neighbouring fence lines, with next-day paperwork and an option to progress into a 5-year interest-free treatment plan and a 10-year insurance-backed guarantee.

A final word on “requirement” vs reassurance

It is tempting to treat the Japanese knotweed RICS survey requirement as a box-ticking exercise - something you do because someone asked for it. In reality, the value is bigger than that. A good knotweed survey does not just satisfy a lender. It reduces the chance of disputes, protects property value, and gives you a clear route forward if work is needed.

If you are staring at a survey comment and a looming deadline, the most helpful move is also the simplest: get the site assessed properly, get the paperwork in hand, and let facts - not fear - set the next step.