Knotweed affecting value of property

Knotweed affecting value of property

0:01 AM, 23rd January 2020, About 2 years ago 2

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In just two months the Japanese housing horror, knotweed, will start to rear its ugly head again and by June it will have grown to over three metres.

Tradespeople comparison site,, has looked at the value being wiped from UK house prices due to the nation’s growing knotweed epidemic and what this equates to for the average homeowner in different areas across the UK.

It’s believed that at least 5% of homes across the UK are affected by knotweed, knocking 10%, or £23,530, of the average UK property’s value. With 29 million homes across the nation, that’s 1,450,000 properties impacted with a huge £34.12bn wiped off in value.

The cost of dealing with knotweed is hefty and can run into tens of thousands of pounds for even a modest size garden, taking as long as five years to treat fully.

All the while, the average UK homeowner will see the value of their home slump by £23,530, this is, of course, higher in London (£47,546), the South East (£32,664), the East of England (£29,128) and the South West (£25,976).

With the highest house prices in the land, homeowners in Kensington and Chelsea stand to lose £119,162 on the price of their property if they find it has been infested with knotweed.

Westminster and Camden are the next largest price losses, facing a loss £93,860 and £86,280 respectively, while South Bucks is the home to the largest loss outside of London at £59,792, followed by Elmbridge (£59,673) and Chiltern (£54,617).

Founder and CEO of, Tarquin Purdie, commented:

“Knotweed is a homeowner’s worst nightmare and there really is no DIY fix for this aggressive backyard vandal. It can take months on end to ensure it has been properly disposed of but can be more costly should you decide to turn a blind eye.

The quicker you can get on top of the problem, the better, as a house with knotweed will not only drop in value but will also struggle to find a buyer.”

UK – 2019 – overall impact of knotweed
Existing homes – approx 29 million homes
Average UK House Price £235,298
Knotweed impact 10%
Knotweed impact value £23,530 (Nov 2019 ave hp)
5 per cent of UK houses are currently affected by knotweed either directly or indirectly
UK number of homes = 29,000,000
5 per cent affected = 1,450,000
Number of affected homes = 1,450,000
Knotweed impact value (on UK ave hp) = £23,530
Total impact in £ value terms = £34,118,258,466
Largest price impact from Knotweed of all UK areas
Location Current Average House Price Impact on value House Price Afterwards
Kensington And Chelsea £1,191,616 £119,162 £1,072,454
City of Westminster £938,596 £93,860 £844,737
Camden £862,799 £86,280 £776,519
Hammersmith and Fulham £731,044 £73,104 £657,940
City of London £709,998 £71,000 £638,998
Richmond upon Thames £665,390 £66,539 £598,851
Islington £627,907 £62,791 £565,116
Wandsworth £599,334 £59,933 £539,401
South Bucks £597,924 £59,792 £538,132
Elmbridge £596,727 £59,673 £537,055
Haringey £569,364 £56,936 £512,427
Hackney £565,018 £56,502 £508,517
Chiltern £546,167 £54,617 £491,550
Three Rivers £529,439 £52,944 £476,495
Barnet £525,458 £52,546 £472,913
East Midlands £197,792 £19,779 £178,013
East of England £291,281 £29,128 £262,153
London £475,458 £47,546 £427,913
North East £130,712 £13,071 £117,641
North West £169,362 £16,936 £152,425
South East £326,636 £32,664 £293,973
South West £259,758 £25,976 £233,782
West Midlands Region £204,238 £20,424 £183,814
Yorkshire and The Humber £165,642 £16,564 £149,078
England £251,222 £25,122 £226,100
Wales £172,574 £17,257 £155,316
Scotland £154,798 £15,480 £139,319
Northern Ireland £139,951 £13,995 £125,955
United Kingdom £235,298 £23,530 £211,769


Peter Fredericks

12:11 PM, 24th January 2020, About 2 years ago

This appeared to work when I tried it a number of years ago:
spray down with industrial strength Roundup mixed with Diesel about 5:1.


12:42 PM, 29th January 2020, About 2 years ago

You can spray with Glyphosate (round up) but this needs doing every year at growing phase for up to 5 years to properly remove. I wouldn't recommend using diesel because this will cause pollution and ground contamination, which is illegal. In my previous job we used to inject undiluted Glyphosate into each growing stem. This is done when it starts to grow after winter, inject each stem with Glyphosate and it will kill the plant and roots. It would be difficult to ensure you'd got it all if you let grow, it has to be at the start of the growing season. Please check the product safety data sheet for health and safety instructions.

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