At SE Knotweed, stand size changes the removal cost because it sets the herbicide visits, the volume of soil to excavate and the disposal fee, so a single clump behind a shed costs far less than a stand running a whole boundary.
A small stand can be treated from around £1,200, while a large boundary-length stand can reach £12,000 by excavation.
At SE Knotweed, removal runs from around £1,200 for a single clump treated by herbicide to £12,000 for a boundary-length stand dug out and removed as controlled waste, because stand size is the second biggest driver of cost after method.
Size sets the number of herbicide visits, the volume of soil to excavate and the disposal fee. The table gives indicative figures for small, medium and large stands, and we measure yours against the RICS 3 metre zone at survey.
| Stand size | Typical extent | Indicative cost | Usual method |
|---|---|---|---|
| Small | A single clump, up to about 5 square metres | £1,200 to £3,000 | Herbicide programme |
| Medium | A garden stand, roughly 5 to 25 square metres | £3,000 to £7,000 | Herbicide, relocation or partial excavation |
| Large | A stand running a boundary or across 25 square metres or more | £7,000 to £12,000 | Excavation or on-site relocation |
A small clump of knotweed, up to about 5 square metres, costs from around £1,200 to £3,000, usually treated with a herbicide programme because the stand is too small to justify the machinery and disposal cost of excavation.
Where a sale needs the site clear quickly, a small stand can be dug out for a little more, but for most owners a monitored herbicide programme is the sensible route. We confirm the figure once the clump is measured.
A medium stand, roughly 5 to 25 square metres, costs from around £3,000 to £7,000, and the method starts to matter more: herbicide keeps it at the lower end, while relocation or partial excavation for a quicker result sits higher.
At this size the distance to the house, outbuildings and the boundary shapes the plan, because the RICS 3 metre zone may bring a structure into play. We set out the options at survey.
A large stand running a boundary or covering 25 square metres or more costs from around £7,000 to £12,000, usually excavated or relocated on site, because a herbicide programme across an area that size takes many visits and a long monitoring period.
The volume of contaminated soil and machinery access are the main drivers, and where the stand crosses onto neighbouring land the plan has to account for that too. A survey measures the full extent before we quote.
A knotweed stand is measured on site by mapping the area of visible growth and adding the RICS 3 metre zone around it, since the rhizome extends underground well beyond the canes and that spread is what the treatment or excavation has to reach.
We record the length, the depth to the dwelling and boundary, and whether the source is on your land or an adjoining plot. That measured plan is what turns a size band into a fixed figure.
Size changes the price because it multiplies every cost driver at once: a larger stand needs more herbicide visits over more seasons, a greater volume of soil excavated and carried away as controlled waste, and a bigger gate fee at the licensed facility.
Excavation is priced largely by the tonnage of contaminated soil removed, so doubling the stand can more than double the disposal cost. That is why an accurate measurement matters more than a rough guess.
A bigger stand does not always mean excavation, because a large stand with no sale deadline can still be treated by herbicide over several seasons at a lower cost, and on-site relocation handles volume without off-site gate fees where there is room to bury.
Excavation earns its place when a large site must be clear quickly for a sale or build. The cost by method page compares the methods, and we advise which fits your stand.
You get an accurate figure from a survey, because size is measured on site against the 3 metre zone and combined with the method and access to produce a fixed price, not estimated from a photograph.
Book a survey and we will measure the stand, confirm the RICS category and issue a costed plan, with the fee often credited against the treatment. See the cost pillar for how size and method combine.
Tell us the address and what a surveyor flagged. We confirm the plant, record the RICS category and set out the figures.