Make an appointment Call now

Japanese knotweed: A major risk to your home

Japanese knotweed, a seemingly innocuous plant, hides a destructive potential that can wreak havoc on homes and infrastructure, leading to significant financial losses and impacting real estate value. Discover the insidious nature of this invasive species, why it poses such a threat, and how a professional building inspection can safeguard your property from its damaging effects.

Nature can be beautiful, but sometimes a great danger lurks behind a green facade. Japanese knotweed is a notorious example. This seemingly harmless plant can cause enormous problems to homes, businesses, and infrastructure. Damage can run into tens of thousands of euros and impact the value and marketability of real estate.

In this article, we explain why Japanese knotweed is so dangerous, how to recognize it, and why a building inspection is essential to prevent problems.

What is Japanese knotweed?

Japanese knotweed ( Fallopia japonica ) is an invasive plant species that was introduced to Europe in the mid-19th century as an ornamental. Unknown to the people at the time, this plant has virtually no natural enemies under ideal conditions—such as in the Netherlands. Knotweed grows rapidly, up to 10 centimeters per day during the growing season. Its root system (rhizomes) can extend meters beneath and alongside the plant.

Once established, the plant is extremely difficult to eradicate. Small fragments of roots or stems can regrow into entire plants, making traditional removal often ineffective.

Why does Japanese knotweed pose such a big risk?

The strength of Japanese knotweed lies in its roots. These roots:

  • Penetrate through cracks and weak spots in concrete, masonry and asphalt.

  • Can damage foundations, walls, patios, sewers and pipes.

  • Cause structural instability to buildings.

  • Pose major risks to the value and insurability of homes.

Mortgage lenders are now asking critical questions about the presence of Japanese knotweed. In some cases, it can even lead to financing denials or significant restrictions.

In short: it is not just about aesthetic damage, but about actual structural threats.

The role of a building inspection

A building inspection plays a crucial role in the early detection of risks such as Japanese knotweed. During an inspection, an experienced inspector not only examines the condition of the home (such as foundations, facades, roofs, and installations), but also looks for risk factors around the house, such as problematic vegetation.

How do you recognize Japanese knotweed?

Note these features:

  • Leaves : Heart- to triangular-shaped, with a smooth edge and pointed tip.
  • Stems : Hollow and bamboo-like, with distinct nodes (similar to bamboo).
  • Flowering : Small white flowers in panicles, mainly visible in August and September.
  • Growth habit : Fast, dense growth; plants can reach 2-3 metres tall.

Are you unsure whether you see Japanese knotweed? A professional building inspection is highly recommended.

Are you looking for a home? Or do you want to make sure your current home isn't at risk from Japanese knotweed?
Then choose certainty and have a professional building inspection carried out by Homekeur BV

👉 Schedule your building inspection directly with Homekeur BV
Visit our website or contact us for more information!

Would you like to make an appointment for a building inspection?

The cost of a building inspection (up to 250 m²) is only €489 including VAT. We'll conduct a comprehensive building inspection and you'll receive a building report. Do you have any questions? We're happy to help and can schedule an appointment with an expert inspector right away if you wish!

Recent articles

Een vrouw wijst naar een tablet die een man vasthoudt en een andere man kijkt mee
blog
13 February 2026
Hidden defects in a home
Hidden defects are not uncommon, especially in existing homes. They are often not immediately visible, but can have significant consequences for comfort, safety, and costs. This article explains how hidden defects are assessed and the role of investigation and inspection.
blazen plooien bitumen dak
video
13 February 2026
Common roof detail mistakes: what an inspection reveals
During roof inspections, problems often turn out to be not in the roofing itself, but in the details. In this practical case study, we demonstrate which installation errors are frequently encountered and why these, in particular, pose an increased risk of leaks and damage.
WhatsApp Image 2026-02-12 at 08.51.37
video
12 February 2026
Three Roof Eave Mistakes That Cause Leaks (And Are Often Overlooked)
Roof problems rarely arise suddenly. They usually start with a minor issue. In this inspection, we see how a torn lead flashing, improper installation, and a loose joint can all pose a serious risk. What should you look for—and how can you prevent them?