Know your Japanese knotweed

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  • | by Dave Jenkins

Years of saving, weeks of viewings and hours of mortgage negotiation: my partner and I thought we’d sealed the deal on the perfect first-time-purchase. Only the valuation stood in our way. No problem, we thought. The building stands up straight, there’s no damp, the roof and windows are new, the plastering is of good quality. Nothing could possibly go wrong…

Then the call came. “I’m sorry sir, we can’t lend on that property.” “Why the devil not?” I snorted. “Japanese knotweed in the neighbour’s garden. We don’t lend in these circumstances.”That was that. Back to square one and £400 worse off. Royal Institute of Chartered Surveyors (RICS) approved Homebuyers Valuations aren’t cheap. The fact it was in the neighbour’s garden added insult to injury.

To be or knot to be?

I did some digging. Knotweed is a huge problem; introduced to the UK in the 1850s as an ornamental plant, by the early 1900s horticulturists were warning about its rampant, destructive properties. Growing as deep as three metres and as far as seven metres, it munches through walls like you or I might a packet of Chewits. It even blighted the grounds of the new Olympic buildings!

Fortunately it’s not a life sentence; professional Japanese knotweed removal firms can eradicate it over several seasons. But in a risk-averse environment,  no lender will wait that long for proof the problem is solved. Yet by not lending on it, they’re devaluing properties they’ve already lent mortgages on which suffer from knotweed. Something needed to be done. And I spoke to the man who tackled the weed head on. Last month Philip Santo, of the RICS Residential Professional Group,  published guidance which will radically change how mortgage lenders consider knotweed.

Tying the knots

“There are three strands to the work we’ve been doing,” he explains. “On one side you’ve got chartered surveyors doing the valuations. On another side you’ve got the lenders. On the third side you have people who offer treatments. Until last month all these three were working independently of each other in terms of dealing with Japanese knotweed.” The problem was the lack of consistency among the knotweed specialist.

Santo described the extremities of their work; some companies provide detailed documents explaining how bad the problem is, how they would remove it, how long it would take and how much it would cost. Meanwhile other companies provide a scrap of paper saying they’d remove it for £20. This inconsistency meant lenders would almost always say no if knotweed, of any distinction, was present. An agreed method and measurement system was needed, just as there is when a valuer spots damp or rot. “This is in keeping with an already established process,” says Philip. “Everyone knows where they are.

Established organisations exist and standards are recognised. Provided the company asked to do the work is a member of one of those organisations, the lender is happy to move forward. Now with Japanese knotweed that’s not the case. There has been no trade body representing the knotweed treatment industry.” Philip was the first person to get competing knotweed specialists speaking to each other. In his words “they hate each other’s guts” but, like valuers and lenders, they understood progress was essential. A plan was developed and, as of March 2012, there is now an authoritative body in place to regulate treatment processes and measure the risk.

The Property Care Association, who also regulate companies who combat damp and rot, now have an invasive weed department who deal directly with the eradication firms. The assessment is based on the distance from the property. If the growth of the knotweed is within seven metres it’s high risk. If it’s over seven metres, but still within the grounds, it’s medium level risk – something needs to be done but it’s not causing serious damage to walls of the house.

Once it’s beyond the boundary, as long as it’s seven metres away from the habitable area, it’s moderately low risk and can be ignored. Unfortunately in my case the knotweed was within seven metres of the property, so my mortgage lender would’ve declined anyway, but the new guidance does empower the homebuyer. “If you’re having problems with knotweed and lender attitude is still a point blank ‘no’ then challenge them,” states Santo. “Ask them if they’re reflecting the PCA treatment availability and RICS risk assessment protocol. If they’re not reflecting those realities they need to be doing that.”

How to spot knotweed on your potential property

Spring: Purple shoots emerge from the ground, eventually forming thick canes.

Summer: The canes develop purple flecks. By late summer they sprout spiky clusters of off-white flowers.

Winter: The flowers die off leaving dead, hollow brown bamboo-like canes standing often as tall as three meters.

How to spot other problems on your potential property

  • Step back and look at the roof. Are there any missing slates and tiles?
  • How superficially has the house been done up? Has it been tarted up or is it pristine?
  •  Look at the quality of plumbing in the airing cupboard. - Are the powerpoints different ages in different places? Are they located low down on the skirting board? This suggests the insulation is old and needs replacing.
  • Make sure self-seeding trees such ashes and sycamores aren’t growing too close to the house. They’ll clog gutters and are expensive to get rid of. - Trees also draw water from the soil. This is problematic on shrinkable clay soil (large parts of London and much of the South East). High risk trees are oaks, elms and willows. - Are there green stains underneath gutters? This is where water been continually splashed against the brickwork, causing damp problems.

These guidelines do not make you a chartered surveyor: they just help you assess the property and inform the questions you ask the estate agent and seller. A detailed valuation such as an RICS Homebuyer’s Report or a full survey is highly recommended and can save you thousands in the long run.