Knotweed Nearby but Under Control? Here's What RICS Category C Means

Last time we looked at RICS Category B. This time we take a look at RICS Category C.

If Japanese Knotweed has been found on your property but isn’t causing any damage, it likely falls under RICS Category C.

This category means there’s an infestation within your boundary, but it’s not affecting your home’s structure or limiting access to outdoor space. Sounds reassuring—and it is! In most cases, this is seen as a low to moderate risk, and the impact on property value is usually modest.

That said, most mortgage lenders will want a proper treatment plan in place. This means hiring a qualified specialist, usually a PCA-approved contractor, to assess the site and recommend the best course of action. A long-term Knotweed Management Plan, backed by a 5 or 10-year insurance guarantee (depending on the lender), is often required to keep lenders and buyers happy. Some lenders will only consider lending on RICS Category C or D.

It’s also worth noting: if the knotweed is growing within 3 metres of a building or boundary, it can raise more concern, even in Category C. That’s why early action is key.

So, if you’ve got knotweed but no visible damage—don’t panic. With the right plan and professional support, it’s totally manageable, and you can move forward with confidence.