Yes, damage can be caused to buildings by Japanese knotweed, particularly where the knotweed has been left to establish itself over many years. However, the extent is often overstated, and some of the horror stories you may read in the press or on the internet are there to sensationalise and scare you!
But Japanese Knotweed can cause damage to land, hard surfaces, waste and water pipes, foundations and we have seen Japanese Knotweed growing out of cavity walls and chimneys. The rhizomes can grow as big as a small car over several years so it’s understandable that it can cause significant damage to land and property if left untreated.