Internal wall cracks and dropped floor and ceilings on 70s extension!?!?!

[sweetbabygee]

Hi all, newbie here. Recently moved into a 3-bed detached house with double-storey rear extension that is causing me more headache with each day. We didn't do homebuyers survey (apparently didn't need one as my husband was confident that he can spot any issues himself) and I now wish we had. One of the issues that has been bothering me since we viewed the house is a dropped floor and ceiling in the upstairs bedroom that had been extended. We ripped the carpets out and it appears that the floorboards are covered as seen in photo so not sure what is going on under there exactly but there is a slope down from where the old part of the house meets the 70s extension (see arrows). There are also internal cracks on the walls along where the extension joins the house. At first we thought that the builders had miscalculated and build the extension slightly lower, but then I noticed that the dining room, which is under the extended bedroom, and is also extended, has a slightly misaligned ceiling and a crack along it as well. There doesn't seem to be an RSJ supporting the upper extension - could this be the issue? Can't see any cracks on the outside apart from one going down from the ground floor extension window. Do we need to get a builder/structural engineer to have a look at it. Are we going to need to put an RSJ in? We are due to have windows replaced in the upper extension soon and lintels put in as obviously they were missing, so I'm just worried that if we then have to do some work to the structure of the extension the windows may become misaligned. Any suggestions on what to do will be greatly received. Happy to add more photos. Thanks!

 

[Mr Chibs]

Think you need to post more photos showing the other cracks. Also a photo from outside.

My SIL extension is quite similar to this, and it slopes down and has a step in it.
Turns out, it was badly built, but whilst under the floor I noticed a ventilation issues and rotten joists etc, all of which can be sorted.

How are you sure there is no RSJ supporting the upper extension?

Take more photos and post, others will comment.

And try to stop having a headache over this. I have been in a similar situation before.

 

[^woody^]

I think your husband already posts here.

If the ground floor, first floor, first floor ceiling and extension walls have dropped equally compared to the main house, then it's a movement problem.

If it's just the first floor, then that's just a quality issue with that.

Cracking may or may not indicate an issue. Its common.

You'll need to detail what has moved, where and by how much, with photos if possible.

 

[sweetbabygee]

Thank you. I've added more photos. The RSJ is just what I'm guessing really as we have a more modern extension on the other side of the house and you can see the RSJ there being lower than the rest of the ceiling. With the rear extension the ceiling just meets together so nothing visibly extending down unless something has been put above the ceiling.

 

[sweetbabygee]

And no, my husband doesn't post on here.

I think your husband already posts here.

If the ground floor, first floor, first floor ceiling and extension walls have dropped equally compared to the main house, then it's a movement problem.

If it's just the first floor, then that's just a quality issue with that.

Cracking may or may not indicate an issue. Its common.

You'll need to detail what has moved, where and by how much, with photos if possible.

 

[Mr Chibs]

I think I would err on the side of the extension having an lintel/beam of some description, possibly set higher up, so you can have a continuous ceiling.

Step crack could be some movement, if that's in the last 40/50 years perhaps not the worry you think, I would monitor it for the next 6 months a year to see if it still moving.

Also your ground level outside is too high, heavy rain can get in the air vent at ground level, ideally the ground level should be two bricks lower (minimum) than the vent.

Poor ventilation under the floor can lead to the joists rotting and this may be a contributor to the slopey floor, although it's probably more like shoddy build. I would rip up the floor sheets, remove some floor boards and see what's what.

My SIL's floor was like this, similar sized room etc. She had rotten woodwork and worm damage, this is quite easy to rectify own DIY basis.

Post a wider photo of the outside please.

 

[^woody^]

TBH, the cracking looks old. The vertical cracking is common with extensions.

The uneven floor/ceiling looks old too and more of a poor quality build issue.

The only way to tell if there is ongoing movement, is to involve a structural engineer to investigate and potentially monitor the extension over several seasons