# Forum Home Renovation Brickwork  Soil back filled against brick wall, drainage issues..

## mudbrick

House is cut into a clay hillside and the wall on the high side of house has about a metre of soil against it. 
It seems the builder didn't drain that soil at all so in heavy rain it fills up with water and water comes through the wall and under the house ...Almost like a series of freshwater springs!
Just to make it a pain there is a pergola and all the rest of it on that side of the house but what's the proper way to solve this drainage issue? Should we bring in a small excavator and dig the soil out and put a big ag line and gravel bed in there? Maybe waterproof the outside of the bricks too?
Cheers

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## cyclic

> House is cut into a clay hillside and the wall on the high side of house has about a metre of soil against it. 
> It seems the builder didn't drain that soil at all so in heavy rain it fills up with water and water comes through the wall and under the house ...Almost like a series of freshwater springs!
> Just to make it a pain there is a pergola and all the rest of it on that side of the house but what's the proper way to solve this drainage issue? Should we bring in a small excavator and dig the soil out and put a big ag line and gravel bed in there? Maybe waterproof the outside of the bricks too?
> Cheers

  Merry Christmas, You are correct on all points and, 
make sure the bottom of the ag drain and waterproofing is a minimum 100mm below the inside floor level,(preferably more) and the ag drain must drain off to a lower exit point .

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## mudbrick

Happy New Year!
If only there was an easier way. Oh well at least we now know what needs to be done!
the ag drain will be about 800mm below floor level. 
If I don't do this myself who would be the best trade to call? landscaper or plumber drainer perhaps?

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## Oldsaltoz

> House is cut into a clay hillside and the wall on the high side of house has about a metre of soil against it. 
> It seems the builder didn't drain that soil at all so in heavy rain it fills up with water and water comes through the wall and under the house ...Almost like a series of freshwater springs!
> Just to make it a pain there is a pergola and all the rest of it on that side of the house but what's the proper way to solve this drainage issue? Should we bring in a small excavator and dig the soil out and put a big ag line and gravel bed in there? Maybe waterproof the outside of the bricks too?
> Cheers

  Hi Mudbrick,
The waterproofing should go on the back of the wall, same side as the Ag drain. 
The waterproofing should extend below the bottom brick and onto the footings. 
Then the top of the Ag drain should be below the wall to footing joint and a fall to the end, or both ends.
Gravel should be 100 mm below pipe and around it, then at least 200 to 300 mm above the pipe, anything above that should be a free draining material up to 50 mm. 
The waterproofing should be covered with a sheet to protect it from damage when backfilling, coreflute is popular for this. 
Good luck and fair winds.   :Smilie:

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## mudbrick

Thanks for the informative responses guys. Now 2 more questions come to mind.
Oldsalt what did you mean about "up 50mm"?
And if we want to lay some nice big pavers over this drain (ie over the gravel ) how would we go about that?
3rd question lol, the house is 20 something years old so those bricks have been wet for a lomg time. Does that change thr process at all? Would they need to dry out before we paint the waterproofing on them?

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## Oldsaltoz

> Thanks for the informative responses guys. Now 2 more questions come to mind.
> Oldsalt what did you mean about "up 50mm"? 
> (Should read)then at least 200 to 300 mm above the pipe, anything above that should be a free draining material *up to 50 mm.* 
> And if we want to lay some nice big paver's over this drain (ie over the gravel ) how would we go about that?  Just extend the gravel out so the surface water runs under the paver's. 
> 3rd question lol, the house is 20 something years old so those bricks have been wet for a lomg time. Does that change the process at all? Would they need to dry out before we paint the waterproofing on them?

  They can be damp provided a water based waterproofing system is used. Sikaflex make on that is tar based.  
Good luck and fair winds.

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## Marc

I remember a case where we built a concrete block wall on a boundary line and our wall was about one meter below the neighbours level. I asked the excavator to dig some 1.5 feet further to allow for building a drain but he was not game and we had no access to the neighbouring property. So we built against the dirt. When the rain came the wall was a big patch of wet. 
I finally found a contact for the next door owner and got permission to enter with a mini excavator. We dug all the way down to the footings and after rinsing the wall from dirt, we painted the wall with a clear almost watery substance that was liquid silicone. the blocks sucked the stuff up big time. Later we lined the wall with a thick agricultural plastic over the dirt line and all the way to the bottom of the ditch and up a bit. Then came a big piece of geotextile covering both sides of the trench and extra to cover the top. Ag pipe all the way along the wall and out the end, and filled the trench with recycled concrete 10-20 mm mixed, covered the top with the extra bit and then 2 inch of sand and some bricks to pave over it. 
This was about 20 years ago and the wet patch never came back. I have not seen that liquid silicone paint for a long time though.

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