Settlement after a side extension

[Miss h]

in the summer (2017) we had a side extension built. Single story, it’s a garage, utility and bathroom. Since just before Christmas I have noticed cracks in the original parts of the house in all 3 bedrooms, including across the ceilings, the hall and staircase and kitchen. Most are hairline cracks a couple are slightly more than this maybe 1mm. One crack in the spare room is worse than the others and appeared while foundations were being dug but has not changed, the window in that room now sticks (crack just below it) and the front door catches too (the front door is below this window)

The foundation for the new bit is a concrete pad with steel mesh in it. But it is lower than the original foundation to the house and the ground my house is built on is not brilliant (1940s or 50’s my house was built)

Are cracks like this just settlement or should I be worried ?

Thanks is advance for any advice.

 

[tomfe]

in the summer (2017)
Thanks is advance for any advice.

That might make a good song title.

Could you take some pictures?
The house should have settled a long time ago, with you having work done and now seeing some movement I would have thought they are related.

 

[Notch7]

Did you have a new opening between house and extension?

Perhaps the extension meant the ground under that part of the house started to dry out resulting in settlement of the shrinkable clay.

 

[Miss h]

No new opening between the old and new part of the house. What was the side door to the drive is now an internal doorway. The foundations were dug for a couple week with no action while building regs changed their mind 3 times how to tackle the foundations due to the ground type.

I can take some pictures during the day.

 

[^woody^]

Yeah that summer seemed to last forever.

Cracks on both sides of external walls would be foundation movement and not normal settlement. At the moment, it could go either way for movement or heat shrinkage, so photos would help.

But binding windows and doors at the same time (despite being common in winter) would make me lean ( ) towards foundation movement.

I could imagine circumstances where excavation below existing foundations and then inadequate back filling could allow the existing foundations to shift.

 

[rssteve]

As the cracks appeared whilst the foundations were being dug surely this means the soil below the existing house has moved out and dropped slightly.