patio job and DPC in wall

[milktwosugas]

We are getting our existing cracked patio and concrete path replaced with a new sandstone patio.
It was recommended lowering path depth to below the air bricks

to avoid splash back. The kitchen is a solid floor and
Below the concrete were a layer of bricks which have been removed. The builder is now saying the foundations are shallow at the corner of the kitchen and need some sort of work.
The plan was to lay drainage to a soakaway. What should be the next step now? Render? French drain gravel-filled? New acco drain.
The house is built around 1900 brick and lime mortar.
Hoping to be better informed before more work goes ahead.

 

[blup]

Does he mean the removal of the current slab and lowering of the new one will affect the foundations? That concrete is a lot newer than the house, so there will be an original lower level to work from.

Blup

 

[freddiemercurystwin]

I think the OP is saying the foundations have been revealed in the corner under the door so will have to be accommodated, though is the OP or whoever is doing it sure that's the top of the foundation as it looks like it stops where the door ends? Is it not just a concrete bed that was laid to sit the original drain on? The fence post concrete will also need to some thought.

 

[milktwosugas]

@blup Yes. He means the newer concrete slabs. I agree there is a good layer of brink below this. One corner brick is damaged partly missing and the bricks are dirty and damp as they have been under the concrete and brick layer for many decades.
I believe/ hope they will dry out in time.
My builder suggested dryzone injected into brick work as a dpc as belt and braces approach. But I'm not sure it needs it. There was silicone injected dpc done 30 years ago and I've no damp in the house now.
Next to the house he suggests leaving a gap with a gutter drain with 'decorative stones' to fall along the house and link with down pipe drainage to soakaway.
The rough brick work under the door looks bad and he is suggesting we concrete over it. But wondering if I should wait and get someone to do lime render instead.

 

[milktwosugas]

foundations have been revealed in the corner under the door so will have to be accommodated, though is the OP or whoever is doing it sure that's the top of the foundation as it looks like it stops where the door ends? Is it not just a concrete bed that was laid to sit the original drain on? The fence post concrete will also need to some thought.

Hi, thanks. The concrete bedding under the door needs attention, yes. He wants to redo the concrete at least there.
But I don't think it is the foundations revealed now, just dirty bricks and one that's broken and goes in slightly on the end corner by the down pipe. That need making good somehow. Just wondering how is best?

 

[freddiemercurystwin]

He just needs to dig out what he needs in order to accommodate a drain but it doesn't look like there will be much that needs digging out. That said you can get low profile drains less than 60mm deep. I'd be more concerned about the state of the wall which will now be exposed, need to wash all that mud off and see what's what ....

 

[milktwosugas]

Had a look this lunchtime.The mud has dried and been brushed off on the dodgiest corner. Should it be made good somehow before the sub-base hardcore goes down and compacted and the mortar mix. House is over 120 years old and not fallen down yet!

 

[milktwosugas]

Here is the area under the door. You can see the seal that has come away from when the door was installed. There is a gap below that needs sealing to keep water tight.what is the best solution here?

 

[milktwosugas]

Is it worth getting a structural engineer in to advise? I could ask the company doing the work to clean off more clay soil. But I'm conscious this may just make more problems. I'd really appreciate any advice.

 

[freddiemercurystwin]

Can't see much in that first photo, it'll all need cleaning up no matter what.

 

[Odds]

Didn't you ask about this job last year?
Those photos look familiar...but i recall something had to be done about the brickwork below the existing level before installing a dpc under new slabs. Water seal on the brickwork would help and a gap between slab and brick to help drain the area.

 

[milktwosugas]

@freddiemercurystwin thanks. I see.
I think the contractor knows this will take more time and make him have to delay lined up jobs...I will tackle it today.

 

[Odds]

Are you set on sandstone slabs?
Have a look on TilesDirect. They're having a sale on outdoor slabs. Brazilian slate looks great and is hard wearing in damp areas.

 

[milktwosugas]

Hi @Odds, thanks.
This work started on Monday. I've not posted about it before. I'm in a steep learning curve here. I was reading today about clay soil and the problems caused by dry summers and shallow foundations. It wasn't happy reading
I have asked for a gap to be left between brickwork of the house and the patio to help drain the area.
Noy sure about waterproofing on lime mortar. I've read not recommended as it needs to breathe. If I need to get extra work done, so be it but want to get the right work done.

 

[JohnD]

In the event of a long-term water leak (very common in old houses, usually from cracked gullies and downpipes, also from buried waterpipes) the lime mortar can wash away below ground leaving the bricks loose. You can hose out the mud from the joints and repack with stiff cement mortar. Also discover and replace the leak. Brickwork below ground does not "breathe"

Your new levels must be below the airbricks and the original dpc. Silicone is not needed and will not help if the fault is not rectified.