Has Neighbours extension caused my house to develop Subsidence?

[mp3wizard]

1930's semi detached house, neighbour next door has the builders in to build a side/rear extension, at the back of neighbours property he has a concrete base and he was about 10 inches higher than my level, the digger has smashed up all the concrete and they have dug out about 3 foot in preparation for the extension.

Huge loud booms and vibrations were felt during the work, today I was easyfilling some walls as I've had a rewire so making good some plasterwork and also had some bifolds fitted and I noticed some new cracks in the walls, these were plastered about 6 months ago. I appreciate that this can just be settlement cracks from the work I've had done with, but today I also heard wallpaper ripping upstairs due to crack so i'm a bit worried that it could be structural.

Here are the pics of upstairs, what do you think is it that bad? and should I contact an insurer to get an expert out?

The house is/was in need of modernization and there were cracks before, but I took the wallpaper back a bit and didn't realise how far they stretch.

Not sure if it's worth pointing out to neighbor also as if it is serious then insurers might need to claim off of the otherside.

What your looking at is the back bedroom, the cracks in plasterwork downstairs are in similar position, and there is small hairline cracks looking at brickwork outside about 1-2mm, about 6ft in length, I only just masonary painted it a few months ago, so it's obviously quite fresh.

That's my ramblings over with, any advice or guidance is appreciated apart from should of got a survey lol

 

[mp3wizard]

last 2 pics

 

[oldbutnotdead]

First one- how close is the neighbours trench to your house? Does this trench run alongside your walls (or do you not have any sort of extension)?
Do you know your neighbours, are you on on reasonable terms with them? Did they tell you this extension was happening, have you seen any plans, have you had any contact about planning permission?

If this trench is alongside one of your house walls then there is the possibility of damage, especially if the trench is deeper than your foundations. Get some pics of the trench with a tape measure in it (so you know what the depth is rather than guessing) and with your house walls in shot (so the proximity can be measured from the pics as well). Also do a load of internal and external pics of that side of the house, put a spirit level or plumbline down that wall, take pics- you're building a record of before/during evidence here.

If you had no notice of the extension from planners then it may be a permitted development job but it is highly likely to need building regs & think building control have shut down except for emergencies so they shouldn't be working. If the trench is alongside your house or any part of it is within a couple of feet of your house then you have legitimate grounds for concern, give your councils' environmental health or building control team a ring tomorrow, explain what's going on and take it from there. If you want the job stopped then call Plod- social distancing, essential works etc. etc.

And now the better news (maybe). None of that plaster in those pics looks fresh (so can't comment on cracks in the new plaster). All those cracks look ancient and nothing to worry about.

 

[mp3wizard]

Thanks for reply, so yeah I don’t have any extension, all my garden is earth except a concrete path which is next to the back of my house, the area of concrete they broke up was next directly behind there house, all along the back of the house upto the boundary line like a patio area but in solid concrete about 1 foot deep, it’s been there for a longtime all around the back of their house.

I saw some cracks in that area upstairs so I knew it wasn’t in great condition but to hear the wallpaper ripping freaked us out a bit to think the crack was getting bigger and that the back of the house was going to collapse.

I don’t want to interfere with their works I just want to make sure my House is structurally safe, I’m thinking to phone insurance tomorrow, explain situation, get an expert out ASAP and leave it there, hoping they can do it free of charge.

 

[Diver Fred]

Is the neighbours the other half of your semi? How close to the party wall has been dug?

'30's house may not have very deep foundations (mine is only around 1 foot in total including brick courses.
Have the builders already undercut the existing house footings? They shouldn't have until ready to pour the concrete into the trench - the under cut ought to be done just before the concrete is due and shall go up to the existing footing the old footing are supported on the new.

 

[mp3wizard]

Is the neighbours the other half of your semi? How close to the party wall has been dug?

'30's house may not have very deep foundations (mine is only around 1 foot in total including brick courses.
Have the builders already undercut the existing house footings? They shouldn't have until ready to pour the concrete into the trench - the under cut ought to be done just before the concrete is due and shall go up to the existing footing the old footing are supported on the new.

Looking at the picture it looks like it’s actually 1foot that has been dug up, there is no boundary wall, all that seperated us was a small string fence, they removed it and dug our to the boundary line, it is the other half, they haven’t dug footings yet, it’s just been levelled

 

[mp3wizard]

Is the neighbours the other half of your semi? How close to the party wall has been dug?

'30's house may not have very deep foundations (mine is only around 1 foot in total including brick courses.
Have the builders already undercut the existing house footings? They shouldn't have until ready to pour the concrete into the trench - the under cut ought to be done just before the concrete is due and shall go up to the existing footing the old footing are supported on the new.

 

[Diver Fred]

Some pictures of the outside and the work that has been completed against the building will help.

 

[mp3wizard]

Thanks for replies so far, I've had someone out and there pretty sure the cracks are old like you said and nothing too much to worry about, so I'm going to keep an eye on it, put some masking tape on the crack, if it moves or tears i'll certainly come back here, cheers

 

[securespark]

Is there just the one crack in the wall outside?

 

[mp3wizard]

yes from what I can see its just a fine hairline crack, there doesn't appear to be cracks on the outside of the house, where there are the big cracks inside

 

[oldbutnotdead]

Didn't see any big (5mm or more wide) cracks in your pics, only ancient plaster cracks

 

[mp3wizard]

yes sorry your right, I say big but more like 2mm, big I guess compared to a hairline crack outside

 

[oldbutnotdead]

Cracks in the outside walls (even hairline cracks) can give you all sorts of grief with rainwater penetration. Lazy fix is clear silicon (it'll act as a useful telltale of any later movement as well), proper would be repoint (if the cracks are in the mortar), both may draw the eye so do an inconspicuous bit first