If you are looking to buy or sell development land you should be aware that Japanese knotweed can significantly reduce its value.
The reduction in value is normally calculated based upon the cost of remediation plus the risk factor for the inherent risks associated with developing knotweed affected land.
Typical risks include;
- Difficulty in securing external funding on land affected by knotweed
- Delays caused by planning objections from aggrieved neighbours
- Civil nuisance claims by adjoining owners for knotweed encroachment
- Increased costs and delays to construction
- Saleability of the developed land
- Litigation risk post sale
Cost of remediation is relatively easy to determine, usually being assessed on worst case scenario physical excavation and off-site disposal to landfill, which can amount to tens, if not hundreds of thousands of pounds.
Delays in construction programmes cost money. Unfortunately, Japanese knotweed remediation is not a precise science and anyone with experience of working in the ground will appreciate that plenty can go wrong.
Common examples include encountering groundwater, ground contamination, below ground obstructions such as live services, all of which increasecosts and result in time delays.
For housing developments nearing completion, savvy solicitors acting for buyers will ask whether the site is or was previously affected by knotweed.
The developer will need to disclose the facts or risk future litigation. The buyer, backed by his solicitor and lender, may demand an insurance backed guarantee (IBG) for a period of 10 years. If it can’t be provided it’s likely the sale will stall.
A developer who does not disclose to a buyer that the land was affected by Japanese knotweed puts himself at unnecessary litigation risk. If Japanese knotweed emerges, the buyer as the new owner will be annoyed, and ask the developer to put things right. The new owner may also decide to claim for diminution in value.
If however the developer discloses that knotweed was present and offers a plot specific IBG from a reputable knotweed specialist the new owner will be able to call on the IBG. The developer in this instance should be better protected from any litigation risk.
A good knotweed specialist will help a developer choose the right remediation method, provide the guarantees likely to be required by any buyer and their lender, and avoid the myriad of pitfalls found on knotweed infested development sites.
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