Subsidence risk due to Pyracantha

[ivahunch]

The side of our 2 storey 1970's extension is adjacent to next door's detached garage. Our neighbour planted a Pyracantha just behind their garage in land which is about 2 ft above our patio, just behind our fence (our gardens go up hill). So the Pyracantha is about 1.8m from the corner of our extension. Our extension has a foundation depth of about 2ft 6in in London clay. So the bush is planted in soil which is about 4ft 6in above the footings. I am concerned that the Pyracantha is now quite large. So I have dug some exploratory 2ft holes in our flower bed just beyond our patio path and next to the fence by the Pyracantha but not yet found any roots. Do you think the Pyracantha is close enough to be a future risk of subsidence?

[AsleepInYorkshire]

The side of our 2 storey 1970's extension is adjacent to next door's detached garage. Our neighbour planted a Pyracantha just behind their garage in land which is about 2 ft above our patio, just behind our fence (our gardens go up hill). So the Pyracantha is about 1.8m from the corner of our extension. Our extension has a foundation depth of about 2ft 6in in London clay. So the bush is planted in soil which is about 4ft 6in above the footings. I am concerned that the Pyracantha is now quite large. So I have dug some exploratory 2ft holes in our flower bed just beyond our patio path and next to the fence by the Pyracantha but not yet found any roots. Do you think the Pyracantha is close enough to be a future risk of subsidence?

Pyracantha will not cause subsidence that I'm aware of. It's usually tree roots that damage foundations as they draw large amounts of water from the ground causing shrinkage and subsequently heave.

AiY
Nope - I take that back - checked the NHBC requirements here. NHBC Guidance Planting trees near your home

[Lootman]

Pyracantha will not cause subsidence that I'm aware of. It's usually tree roots that damage foundations as they draw large amounts of water from the ground causing shrinkage and subsequently heave.

Nope - I take that back - checked the NHBC requirements here. NHBC Guidance Planting trees near your home

As well as trees and some shrubs, bamboo rhizomes can cause a great deal of damage underground, growing into any crack or hole in the foundation, and is rather fond of pipes and ducts as well. Always plant them well away from any structure, or else contain them.

Speaking from personal experience . . .

[88V8]

Pyracantha is a fairly modest shrub.

In our previous house, on clay, we had a prunus 3 feet from the front of the house, trunk was 2 ft diameter. And an old laburnum nearer than that.
House was on 18" strip footings.

I wouldn't worry about the pyracantha.
Now if it was a willow........

V8

[bungeejumper]

Not forgetting holly, which shouldn't ever be grown next to a structural wall. Roots like an oak tree, they can disrupt anything. Some large conifers can also subside the soil by drying it out. But pyracantha? Most unlikely.

BJ

[Lootman]

Not forgetting holly, which shouldn't ever be grown next to a structural wall.

If your wall happens to be a dry stone wall, then almost any ivy or creeper can be a problem, as can removing it as well. It took me several years to remove the ivy from my dry stone walls, some of which were 4 metres high. And any stones dislodged in the process can cause injury. The ivy had become part of the structure of the wall, holding it up in some places.

Roots like an oak tree, they can disrupt anything. Some large conifers can also subside the soil by drying it out. But pyracantha? Most unlikely.

Yes, and removing such a tree can cause the opposite problem, since suddenly the soil becomes saturated as there is no longer a tree to hoover up the moisture. We had a birch tree close to our house that didn't seem intimidated by concrete at all. It just moved it out of its way.