Japanese Knotweed Damage to Homes in MD & VA

There are many weeds throughout Maryland and Virginia. And it seems most of them find our lawns and gardens at some point during the year. There is, however, one particularly noxious weed that can cause significant damage and that is also very hard to eradicate. It’s the Japanese knotweed.

What Is Japanese Knotweed?

Originally valued as an ornamental plant, the Japanese knotweed escaped into the wild, where it crowds out native plants and leaves the soil exposed to erosion. 

Its stem can grow up to three inches per day and reach up to 10 feet tall. The roots can grow as much as 20 feet deep. It can regrow from a piece of the plant as small as a half-inch. Then it forms an underground network of rhizomes with lateral shoots and roots that can spread up to 70 feet from the nearest stem.

When it’s growing in your yard, it can damage home foundations, driveways, walkways, and patios. It finds any cracks or weak spots, growing through them, gradually expanding and causing still more damage.

How To Identify Japanese Knotweed

The stem is a hollow segmented cane, much like bamboo. It’s green with purple speckles. The leaves are bright green and heart-shaped, also with purple speckles. The leaves are staggered along the stem. The plant sheds its leaves as the weather gets cold.

Creamy greenish-white flowers form in clusters up to four inches long from late August through September. You can find a comprehensive guide to identification, including a video guide, at Knotweed Help. 

Damage From Japanese Knotweed

With its wide root growth pattern, this plant can find drainpipes and home foundations. They can enter drainpipe joints and cracks, clogging the pipe, widening the cracks, and even splitting it open. 

They can also grow underneath concrete and asphalt, finding cracks and weak spots. The stems then grow up through driveways, walkways, and patios. They expand the cracks and even break up the paved surface.

They can do the same thing with stone or brick retaining walls, as well as home foundations. They find any small openings, growing through them and causing all sorts of damage.

The spread and growth of this invasive weed comes at a huge economic cost. As one example, since 2010, New York City has spent more than $1 million on eradication efforts for a 30-acre patch of Japanese knotweed.

That’s an example of the cost of eradicating the weed. There can also be an impact on a home’s value. Lenders are starting to look closely at any infestation before providing a home mortgage. On top of that, there’s also the cost of repairing the damage.

How To Protect Your Home

Eradicating the Japanese knotweed is extremely difficult. There are several steps you can follow that include: cutting the stems, removing the clippings, covering the area to eliminate light and water, and placing a plastic barrier around the area to stop root spread. 

You can also try a glyphosate-based herbicide, the main ingredient in Roundup. Another option is to excavate the entire area, at least to a depth of 20 feet. All these approaches take time and considerable effort.

You can also consult an expert in eradicating knotweed who has the knowledge and experience to remove the plant without spreading it elsewhere in the process.

We Can Help

We’ve seen Japanese knotweed in Maryland and Virginia from our offices in Baltimore, the Washington D.C. area, Appomattox, Richmond, Roanoke, Virginia Beach, and Charleston, WV. 

If you find Japanese knotweed on your property, contact the professionals at JES Foundation Repair for a free inspection to ensure the weed has not caused damage to your home or its foundation.