Can you sell a house with Japanese Knotweed?
The short answer is an absolute YES! You can sell a house with Japanese Knotweed.
Along with ‘should I buy a house with Japanese Knotweed’ – this is also a question we are asked all too frequently by concerned home owners, who like most of us, do a quick internet search and find greatly exaggerated and sensationalised stories from self proclaimed ‘experts’.
Selling to a Cash Buyer
If the purchaser is a cash buyer then legally a Japanese Knotweed Management Plan does not need to be in place however it is strongly recommended that a Plan is entered into by a Property Care Association (PCA) approved company, such as SE Environmental.
This gives the buyer peace of mind, along with removing any potential guilt from the seller should the Japanese Knotweed not be treated / get out of hand.
Selling with a Mortgage: What Lenders Require
If the property is being purchased using a mortgage then all lenders require a Japanese Knotweed Management Plan to be in place prior to releasing the funds to lend on a property.
Most mortgage lenders will not release funds until the following are in place:
- A Japanese Knotweed Management Plan (JKMP) from a PCA-approved contractor
- A 10-year Company Guarantee
- A 10-year Insurance-Backed Guarantee (IBG)
These must be fully paid for by the seller before the sale completes. The IBG protects the buyer even if the original contractor ceases trading, ensuring continuity of treatment.
SE Environmental includes both the Company Guarantee and IBG as standard in all our JKMPs.
Will Japanese Knotweed Affect the Sale Price?
In some cases, yes, the presence of Japanese Knotweed may reduce the property’s asking price or deter some buyers.
However, unless the plant has caused structural damage to the home’s foundations, it’s very unlikely to prevent a sale altogether. Mortgage lenders simply need to be sure that a professional plan is in place and the risk is under control.
How Japanese Knotweed Is Treated Before a Sale
By far the most commonly adopted remedial method for treating Japanese Knotweed in a domestic situation is via herbicide application due to both cost and ease of access.
Herbicide Management Plan:
- Conducted by trained, licensed technicians
- Applied via foliar spray or stem injection – no heavy machinery needed
- Typically includes 3 years of treatment + 2 years of monitoring
- Average cost: around £2,500 + VAT
When treating via herbicide application a suitably experienced and qualified technician will visit the property and apply herbicide to the plants either by a foliar (leaf) spray or by injecting the chemical into the stems. This is undertaken on foot and so no machinery is needed nor mess created. Typical costs for a herbicide application programme would be in the region of £2,500.00 however the negative of a herbicide application management plan is the time it takes to control the plant. This typically comprises 3 years of herbicide application followed by 2 years of monitoring to ensure no re-growth.
To ensure as much herbicide as possible reaches the roots, as much stem and leaf needs to be present as possible to be sprayed or injected– this can be frustrating for clients who for several months of the year have a visible plant on their property.
Why Can’t Japanese Knotweed Be Treated Earlier in the Year?
SE Environmental gets a considerable number of calls every year asking why we cant undertake treatments any sooner than our first treatment dates in June, this is quite simply because in a usual year (sunlight, temperature and rainfall dependant) the plants are not large enough to treat before then.
Treating plants before this date when they are still small and immature can send the plants into a state of dormancy or promote ‘bonsai’ growth resulting in an infestation far harder to treat.
Should You Try DIY Treatment for Japanese Knotweed?
No, treating Japanese Knotweed yourself using shop-bought chemicals may seem tempting – but it often makes things worse.
Incorrect herbicides, dosage rates, or poor timing can cause the plant to become dormant or regrow in a more aggressive way, making professional treatment much more difficult.
What About Excavation?
Excavating Japanese Knotweed is rarely undertaken in a domestic situation primarily due to cost and access.
- Costs typically range from £7,500 to £15,000 + VAT
- Requires access for a mechanical excavator and space to store and transport contaminated soil
- The benefit? Immediate removal, allowing redevelopment to start straight away
Typical costs for a domestic excavation would range from £7,500.00 – £15,000.00 plus VAT, should the excavation be possible. This being dependent on access for a mechanical excavator, area to store the soil prior to being taken away to registered landfill and a means of transporting the soil, often in excess of 20 tonnes, to the storage area which needs to be secure to ensure biosecurity.
In addition, built structures such as houses, paths, patios may pose issues as may property boundaries where the Japanese Knotweed spreads into several differently owned plots of land. The hole created then usually needs to be filled which requires a similar process in reverse.
The big advantage however of excavation is that the Japanese Knotweed is removed in its entirety in a day or two and once the ground is made good, re-developing can take place immediately.
So, Can You Sell a House with Japanese Knotweed?
Yes , but only with the right plan in place.
If you’re working with a PCA-accredited contractor and have a JKMP (plus guarantees), selling your property is entirely possible.
At SE Environmental, we help homeowners every week who are in the exact same position. We handle everything from surveys to treatment and ensure your sale moves forward without unnecessary delays.
Get Help Selling a Property with Japanese Knotweed
If you’ve got Japanese Knotweed on your property and want to sell, speak to our team. We’ll assess the site, provide a same-day report, and put a management plan in place that satisfies buyers and lenders.
Call us now on 01924 944600
Email: office@seenvironmental.co.uk
