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 Building & Development Requirements & Invasive Weeds

In terms of invasive weeds, when it comes to building & development requirements, UK laws impose responsibilities on land owners (small or large) to manage ‘listed’ (Schedule 9) species on their property.  

If you are a construction or property related professional, this means there are some considerations, common risks and challenges you must consider, whether you’re working on a large development site or a small extension.

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Legal requirements when building & developing

These legal responsibilities may stem from specific legislation e.g. The Wildlife & Countryside Act 1981, Environmental protection Act 1990 or more general (common) laws, ‘tort’ statutes, that protect the rights of neighbours against encroachment etc.  

Other legal obligations can arise from waste management too (all Schedule 9 ‘propagules’ are Controlled waste).

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What are the building & development considerations?


The first priority of a land owner is to prevent the spread of INNS  when faced with a site including so-called ‘Schedule 9’ species.  The movement of personnel and/or vehicles etc. on site can be a significant risk (spreading seeds or rhizomes etc. attached to soil)


Before breaking ground it is critical to assess the further (biosecurity) risks associated with soil movement.  For most sites there should be an established Invasive species management plan in place at the outset; this to include biosecure ‘safe routes’ for diggers etc.

Waste management  

If any ‘green’ waste or contaminated soil has to leave site (see other options below) this needs to comply with the various statutes surrounding the movement of Controlled waste (transfer notes etc.) and only be sent directly to  landfill sites (or incinerators) licenced to receive it.

Options for invasive weed waste management

Option 1: Retaining contaminated soil on site

Where at all possible, if the plans for the site allow it, the best environmental option is to try to retain the contaminated soil on site in either a stockpile (prior to burial) or a bund (for long-term management e.g. with herbicides).  No Environmental agency permit is required if the contaminated soil is managed in accordance with Government guidance RPS 178, but any burial cell plans do need to be notified to EA and details added to plans/deeds.

Option 2: Soil Screening

In certain cases, some intermediary soil screening may be advised to reduce the frequency of propagules (e.g. knotweed rhizome fragments) in the soil but as the process is not 100% reliable the resulting soil is still ‘Controlled waste’ and needs to be managed on site in designated areas.

Option 3: Herbicide long term management

If the invasive weeds are not directly interfering with the development work and/or have been placed in a bund created for the purpose (and can be fenced off) then long-term management with herbicides is possible

All of the above should enable residential or commercial developments to proceed within the legal framework of environmental legislation AND satisfy the mortgageability requirements associated with Japanese knotweed 

More about invasive weed waste management >>

Monitoring after completion of building & development works

No matter the size of the building of development works you are carrying out, if you have had to deal with invasive weeds/plants during the project, you should ensure the invasive weed management plan includes a post-completion monitoring phase. 

Irrespective of the methods/techniques usedthere should be a long-term commitment to conduct monitoring to establish the successful remediation of the target invasive weeds (these are often specified as a part of Guarantees available from qualified specialists such as PCA members).  Some sites may present special challenges due to the risk of new infestations arriving on-site via rivers, roads or other ‘vector routes’ but in all cases (scheduled invasive weed species are difficult to control by definition) there is a risk of new seed germination and/or fragments of root/rhizome re-growing.  In the case of Japanese knotweed, rhizome dormancy is widely reported as lasting 20 years+. 

To summarise, each invasive weed species presents unique challenges, adopting a systematic approach using qualified experts is key to a successful outcome.

  • always have a professional Invasive Weed Management Plan in place
  • be aware of the vector routes (risks of spreading the problem on or off-site)
  • manage wastes arising
  • Ensure long-term monitoring of the site.  

Finding qualified invasive weed specialists

Our members are able to provide expert advice and assistance for all projects small and large and often deal with complex cases involving multiple species and/or other soil contamination concerns.  They can often save their clients significant sums through well-designed, professionally managed programmes.  

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Planning law and a ‘special case’

Apart from the above national laws (with some variations in each part of the UK) there is one example worth mentioning where additional local controls are in place specifically in relation to Japanese knotweed.  Through the planning consent process, due to the extremely widespread presence of Japanese knotweed in the area, the  City and County of Swansea has a Local Plan which includes the specific requirement for a  Knotweed Management Plan to be in place before building work starts.

Improve your knowledge - helpful CPD videos about invasive weeds/plants

Technical documents you can view

For those interested, there is a variety of invasive weed related 'Codes of Practice', Technical Documents, Guidance Notes and other related documents via our 'Invasive Weed Control Document Library'.  Simply click on the button below to view the library.  Documents of interest include:

  • NEW – Herbicide Treatments and Japanese knotweed – PCA Guidance Note
  • Restrictions on the Use of Herbicides on Hard Surfaces
  • Root Barrier and Japanese Knotweed Remediation
  • Waste Classification for Works in a Commercial Setting
  • UPDATED – List of Invasive Non-Native Plant Species

Visit the document library >>

Want to learn more about invasive weeds & plants?

For those interested in learning more about invasive weeds and plants, there is a variety of PCA training options for surveying professionals as well as technical/trade professionals. 

Use the search tool below to find available invasive weed related training courses or simply go to our training & qualifications section.  Alternatively, if you want to chat to someone, contract our training team on 01480 400 000 or contact them online.

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Professional Guidance

For those professionals looking for information, technical help and guidance towards and variety of property related problems, why not check out our 'professional guidance' pages.

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More about PCA Membership 

Interested in taking part in the CPD scheme but you are not a PCA member?  Find out more about membership and why it will benefit you!

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