Cracking between extension and original house

[Jemlou]

Hi

We have just moved into a 7 year old house with a 2 storey rear extension which had sign off late 2023

We have noticed that on the first floor landing there is an area where the two floor heights are different and now we have noticed this cracking

Should we be worried?

[markc]

Are there any gaps appearing? Or cracks wider at the top or bottom? From photo it is difficult to be specific but my first impression is that mortar has been run down the joint and the crack is just mortar shrinkage.

[joe90]

2 hours ago, Jemlou said:

We have noticed that on the first floor landing there is an area where the two floor heights are different

How much? Sounds like differential settlement in the extension.

[DreamingTheBuild]

I think it's very unlikely to be differential settlement myself, I think for one thing DS tends to happen gradually over time, a number of years, I think there is also an element of rotation involved with DS too. Buildings move all the time so it's important not to fear the worst when you see cracks.

 

The floor issue is likely to be something unrelated IMO.

 

 

[George]

You will always get some amount of settlement - the soil under the extension wasn't under (much) load before it was built and when you subject anything to load you will get some level of movement or settlement. Unless it's founded onto rock. This should be fairly consistent over the footprint unless there are differing soil conditions or high point loads.

 

The detail should have been a flexible sealant rather than mortar.

 

However, if the crack is the same width all the way up and there isn't any other sign of distress I would not be concerned. Once the initial settlement has occurred you should be ok to rake back the cracked mortar and repoint. 

 

Edited March 21 by George