Wet clay and clay heaving in crawl space

[JohnD]

We will definitely check for water table.

You said the neighbours don't have the same problem.

Are their houses the same height as yours? In the same area? On the same soil?

 

[JohnD]

Here are some additional pics that show how far above the clay are the airbricks. We have checked for leaks from the drains and pipes already. Engineers said there was no leak related problems.

We checked with the neighbours also. None of them seem to be facing issues as severe as ours.

In the pics, there might be a trail of efflorescence on the brickwork running down from the airbrick. Please show us the outside, showing height relevant to ground and any downpipes, gullies, etc

How do you know the engineers are right?

 

[vbhardwaj87]

Is it red?

They are black

 

[martygturner]

Its a case of exclusion, man made water sources : water escape from pipes and drains, inadequate drainage causing overflow eg soakaway too close to the property. etc etc If not then is a groundwater issue and a clay issue.

The clay issue is one of shrinkage and expansion, as its been doing that for a while do you want to dry out the clay ? its probably in its maximum expanded state and that clay will be exactly the same stuff as under the foundations...hence comes the issue of what to do, if you dry it out what will be its shrinkage ? Clay soils have a shrinkage rate in direct proportion to the amount of clay in the soil, just because a soil looks like clay does not mean its pure clay, it can be a mix of types as clay particles bind to other materials in the soil this then looks as if it is pure clay. The next question at what depth is the clay expanding . From the photos I would say that's surface expansion...but,,,,I don't have x ray eyes.

I would get an sample of the soil column from a geotechnical survey, sounds expensive but is not , its just a core sampler on a drill. This will tell you how deep the water penetration is and the shrinkage rate at foundation depth...that's really technical..rolling a bit of soil into a snake and seeing how far you can bend it into a circle without breaking....

If its wet all the way down past the foundations then you need a good geotechnical engineer, drying it out could cause serious instability to the foundations. But here clay is your friend, is pretty impervious, they line canals with it and unless you are sitting on a some serious throughflow ( that's when water makes drainage pathways in the soil) then the likelihood of it being a river is small...but not impossible. Again a geotechnical engineer will do a survey for water transit.

If its surface , ie between foundation depth and the surface I would point to overland flow of water draining off the slope getting in via the wall adjacent to the slope.
Solutions to the wet...sump and pump at the lowest point at the depth you want the clay dry to, ie a 1 foot deep pit., that leaves the clay column wet below and prevents shrinkage. Dig out the slope and tank the brickwork on the slope side. If its not wet to any depth and its just say a 6 inches of penetration increase natural ventilation or mechanical vent the space the space....

 

[vbhardwaj87]

Do you have any pipes or drains in your house that contain water?

(Yes you do)

Much more common than streams.

Yours are old enough to be leaking.

Have your neighbours had similar?

Please photograph the airbricks round the house, showing how far above ground level they are, and the drains, gullies and manholes.

Do you have a water meter?

Apologies on late reply. I had drain person who came today and checked the drains. There were some small roots which he mentioned he will clear them off. But there was no leakage from the drain. He put dye in the water in the morning. No dye has been observed in the standing water below the house. This makes me believe that it may be the ground water.

The clay is wet all around the house. I asked neighbour - they said they did not had this issue as there is potentially concreted.

Yes i have water meter - I switched off all the tap to see if there was any water leak and I could see water meter was not giving any reading that assured that there is no pipe leaking.

THis is mainly surface water - not sure where it is coming form

 

[omph]

Apologies on late reply. I had drain person who came today and checked the drains. There were some small roots which he mentioned he will clear them off. But there was no leakage from the drain. He put dye in the water in the morning. No dye has been observed in the standing water below the house. This makes me believe that it may be the ground water.

The clay is wet all around the house. I asked neighbour - they said they did not had this issue as there is potentially concreted.

Yes i have water meter - I switched off all the tap to see if there was any water leak and I could see water meter was not giving any reading that assured that there is no pipe leaking.

THis is mainly surface water - not sure where it is coming form

Does the roof gutter in that picture have a drain, or is it draining onto the pathway ?

 

[JohnD]

Apologies on late reply. I had drain person who came today and checked the drains. There were some small roots which he mentioned he will clear them off. But there was no leakage from the drain. He put dye in the water in the morning. No dye has been observed in the standing water below the house. This makes me believe that it may be the ground water.

The clay is wet all around the house. I asked neighbour - they said they did not had this issue as there is potentially concreted.

Yes i have water meter - I switched off all the tap to see if there was any water leak and I could see water meter was not giving any reading that assured that there is no pipe leaking.

THis is mainly surface water - not sure where it is coming form

There seems to be a wet patch under the window. Is there a sink inside? A dripping gutter above? Or is the nearby downpipe a source?