What knotweed removal costs

Typical prices

• Typical domestic job: £1,500 to £5,000.
• Herbicide programme: £500 to £2,500 over three to five years (another guide puts it at £2,000 to £5,000).
• Excavation and off-site removal: £4,000 to £20,000.
• Survey: £100 to £300 (another guide says £250 to £500).
• Insurance-backed guarantee: £150 to £750 (another says £1,000 to £2,000).
• Monitoring: £500 to £1,500 a year.

Fantastic Services puts London and the South East at 20 to 30% more. One guide suggests a budget of £3,000 to £7,000 with a guarantee.

Why the guides differ

The figures for a herbicide programme vary up to four times between guides. The gap is mostly down to whether a lender-ready plan with an insurance-backed guarantee is included. Ask each firm what its price covers.

What the quote should say

Ask for a written plan that sets out the method, the number of visits, the monitoring period, the guarantee length and who underwrites it, and who disposes of the waste. A herbicide price that excludes monitoring and a guarantee is not comparable with one that includes them. Check that any firm removing soil is a registered waste carrier.

What changes the price

The size of the stand, how far rhizomes spread, access, whether the plant is near a boundary or structure, and the method you choose. Herbicide is the cheapest and slowest. Excavation is the dearest and fastest, and means disposing of contaminated soil as controlled waste through a registered waste carrier.

If you are selling, the plan must satisfy the buyer's lender, which often means a guarantee. RICS says knotweed rarely causes structural damage, but the cost often comes from lender and buyer reaction.

If you are buying a home with knotweed, the cost of a plan can be a point for negotiating the price. Ask the seller for any existing management plan and guarantee.

Councils and who pays

Councils do not treat knotweed on private land. The landowner pays. See what a knotweed specialist does, and the DIY guide for what you can legally do yourself.