An introduction... Renovation + 1950s + subsidence = a challenge!

[alfaTom]

Very quick lunchtime investigation on the downstairs crack reveals a fair amount of roughfill, and what looks to be a metal mesh, I assume from the previous subsidence repair as there were references to repair meshes being installed.

First image is a small cutaway as well as investigating the coving - this is plaster so explains the tears.

 

In the below image you can see where I've come across the repair mesh as we as something else under it, not sure what it is yet but it looks to just be sitting in roughfill again.

 

 

Below the roughfill is what I assume to be plasterboard as it's not solid like a lintel, but it's also sat about 10-15mm beneath the top layer of plaster which seems excessive. The doorway cut into the wall is about 42cm in depth which is much thicker than other external walls in the house are roughly 28cm there is definitely some buildup on it...

I will have a closer look at the assumed plasterboard as well as the crack to the left of it after work.

R.e. the next steps:
Drain repair sounds sensible, I am just waiting on plans coming back so I can work out best place to put new soakaways in. Thankfully the size of the gardens mean I have a decent choice of locations as long as they pass percolation tests.
 

3 hours ago, George said:

You may still get fine cracking for the lifetime of the building but if I could do all the above for £10k, bank the £20k and just reapply caulk and paint every 5 years I'd be happy. 

 

I would be more than happy with this tradeoff too. Assume at this point we'd level internal floors/ceilings/walls as necessary and leave the house to it's controlled movement.

Edit: For clarity, this doorway is one we would be planning to block up as part of our plans.

Edited July 14, 2023 by alfaTom

[Mike]

 

3 hours ago, alfaTom said:

Below is their suggested works, which involve resin injection across the majority of the front elevation as well as around the gable ends.

Partial underpinning / soil stabilisation raises new issues. You need the entire building to act as one structural element for it to remain stable and crack-free. There's a risk that the part of the building that has been underpinned swaps from being the least-well supported part of the building to the best-supported part, which could still cause differential movement. That's not to say that it should never be done, but it does mean that whoever is designing the solution needs to have carried out a full investigation first. Personally I'd be wanting an independent structural engineer to be doing that, not a contractor.

[alfaTom]

Got bored of work - the crack is above my desk so went back to it.
Found what I believe to be a timber lintel behind the plasterboard.

 

I am not sure what "repairs" this company did previously but it currently looks like they chucked repair mesh over the old plasterboard and covered it?
More needs to come off to find out how far the lintel goes as well as the makeup in between, but if the wood has dried or shrunk I can see this causing some movement upstairs...

 

1 hour ago, Mike said:

 Personally I'd be wanting an independent structural engineer to be doing that, not a contractor.

 

Agreed, I think next steps will be to provide our SE with TP & SI reports, plus the suggestions from the underpinning company.

[Mr Punter]

6 hours ago, alfaTom said:

I honestly did not know about the "upside down" ground aspect and this is something I definitely need to look into more, especially as we'd rather use that cash on other parts of the property if the underpinning is going to cause issues with the rest of the property.

 

We are on land that has about 2m depth of fairly solid clay and made ground, then 18m alluvial silt, then hard chalk bedrock.  The previous buildings on the site had fairly shallow strip footings with no sign of movement.  Our replacements are 4 storey and are on 25m piles.  Anything founded between 2m and 18m would not be very stable.

[alfaTom]

I have been a bit quiet recently - unfortunately, the weather at the weekend was terrible so no investigations outside were completed. I did however get the old cylinder lawnmower running again in the (relative) safety of the garage!

 

I did finish the cut-out above the doorway though. After getting through a layer of plaster, roughfill AND plasterboard I found the lintel over the doorway.

It looks like there is a metal lintel (can be seen below the timber and in the shadow) with the timber resting above it.

I need to get more of it cut out to see how it sits but I didn't want to disturb it too much.

Waiting on the SEs to respond to my queries at the moment around the soil vs drains, and I am waiting for the underpinning company to come back to me with answers about complications from partial underpinning and more info on guarantees.
When I get more information I'll update this thread so the information is there for anyone in the future that may need it.

[Mr Punter]

That is quite a bewildering selection of materials!  Have you checked that the wall textured coating does not contain asbestos?  Given the age of the property you need to be a bit cautious.

[alfaTom]

45 minutes ago, Mr Punter said:

That is quite a bewildering selection of materials!  Have you checked that the wall textured coating does not contain asbestos?  Given the age of the property you need to be a bit cautious.

 

It's certainly a variety pack! Curious to see what I find elsewhere. I may try to cut the plasterboard below off so I can get almost a cross-section idea of the lintel. A shame the SE's seem to be taking their time coming back to me at the moment as that is holding us up currently.

My understanding is that the wallpaper is newer, from 2012 when some work was done to the property. It doesn't seem to have a vinyl layer so it which reduces the chances as far as I am aware.

There is plenty of asbestos elsewhere though; garage roof sheets, soil pipes, guttering etc as well as some tiles in the downstairs w/c.

[Iceverge]

Demo and rebuild! 

 

Its the only way😬.