Insurance-backed guarantees (IBG), explained
An insurance-backed guarantee (IBG) protects your knotweed treatment guarantee even if the contractor goes out of business — an insurer funds the remaining work. It's the document mortgage lenders insist on, it's transferable to future owners, and it typically runs 5–10 years. Without one, a treatment “guarantee” is only as good as the firm that issued it.
What an IBG actually is
When a specialist treats Japanese knotweed, they issue a treatment guarantee — a promise to return and re-treat if it regrows within the term. The problem: that promise is worthless if the company stops trading. An insurance-backed guarantee solves this. It's a separate insurance policy that stands behind the contractor's guarantee, so if the firm ceases to exist, an independent insurer funds the completion or re-treatment for the remainder of the term.
In short: the contractor's guarantee covers the work; the IBG covers the guarantee.
Why lenders and buyers insist on it
A mortgage is secured against the property for years or decades — far longer than many contractors survive. A lender can't rely on a firm still being around to honour a re-treatment promise in year seven. The IBG removes that risk, which is why most mortgage lenders will only accept a management plan that carries one. For buyers and sellers, the same logic protects the property's value and keeps it mortgageable.
If the contractor goes bust, the insurer steps in — your protection doesn't vanish with the company.
A genuine IBG passes to the next owner for the rest of its term — essential when selling.
Satisfies the requirement most banks and building societies set for knotweed-affected property.
Typically 5–10 years, matching the treatment and monitoring programme.
What a good IBG covers
- ✓Completion of the agreed treatment programme if the contractor ceases trading
- ✓Re-treatment if knotweed regrows within the guarantee term
- ✓A defined term (commonly 10 years) named in the policy documents
- ✓Transfer to subsequent property owners for the remaining term
- ✓Backing by a regulated insurer, not just the contractor's own promise
How to check an IBG is genuine
Not every “guarantee” is insurance-backed. Before you pay, confirm:
- ✓The treatment is carried out by a PCA-accredited contractor
- ✓The IBG is underwritten by a regulated insurer — ask for the insurer's name
- ✓The policy names your property, the term and the transfer terms
- ✓You receive the policy documents, not just a certificate or a verbal promise
A “10-year guarantee” from the contractor alone is not an IBG. If there's no separate insurer standing behind it, it fails the moment the firm closes — and most lenders won't accept it.
