Is this subsidence?

[RrogerD]

Even before this latest, very dry summer my parent's house showed signs of cracks. It is originally a late 1800s property with an extension built on the side in the early '60s. When I was a youngster there until the early 80s, there was a separation crack between the old and the new. In fact at one point they had ivy growing through with odd leaves visible in one of the upstairs rooms.

With this latest dry spell, cracks have become visible in the main walls, below the windows of the 'extension'.

My question: is this subsidence? Or could it be called 'settlement cracks' or historic perhaps?

We're not concerned that the place may be falling down, it is more to do with declaring on the insurance.

 

[George_engineer]

That looks like ground movement, likely caused by clay shrinkage. The wide arched opening would be particularly sensitive to any movement and rotation.

Although its not very well defined, in my book subsidence proper is a loss of support to a wall (usually caused by water). In this case, while the clay soil has moved, it is still supporting the building.

Best is to monitor the cracks as you go through winter and the clay moisture content reaches a new equalibrum.

 

[^woody^]

Could also be shrinkage in the wall causing the arch to drop. It will need assessment of other factors.

You can't "declare" subsidence unless it's been diagnosed by a professional. All you know at this stage is that there is a crack.

 

[RrogerD]

Thanks both, for your replies. This is indeed very assuring.
I agree, clay is likely to be the issue. I have the same with a sinking garden wall at my own property.
At the moment i've said to them the same, to keep an eye on things for any change. I'll pop up again in the Spring and Summer to have a look.
For the time-being it seems, the sensible course of action would be to keep shtum about things, insurance-wise.
Thanks

 

[stuart45]

That looks like ground movement, likely caused by clay shrinkage. The wide arched opening would be particularly sensitive to any movement and rotation.

Although its not very well defined, in my book subsidence proper is a loss of support to a wall (usually caused by water). In this case, while the clay soil has moved, it is still supporting the building.

Best is to monitor the cracks as you go through winter and the clay moisture content reaches a new equalibrum.

This is quite possible. A large segmental arch needs a bigger abutment at the corner. Combined with any ground movement, the pressure looks to be pushing the wall apart and it's cracked at the weakest point.
I can remember insurance companies years ago trying to claim that shrinkage in clay soils wasn't technically subsidence.