Concret Patio next to house

[Digger2]

I'm new to this great website, but have tried to do a lot of reading up on my issue.

Our Victorian Semi has a cellar that was always completely dry. Over the years, when there was very heavy rain, we started to get a small inch wide trickle where the concrete floor met the walls.

Always in the same spot. It looks like there is either a deliberate gap between bricks at that spot, or the mortar has been washed away.



The amount of water has gradually increased and eventually has become a few feet wide leak. The floor is now always damp. Water also came in when we let a bath go. So we got the drains looked at and there were cracked and slipped underground clay drains. We got the problem pipes replaced and the sodden clay that was dug out replaced with MOT1 to back fill.



I now need to replace the patio area that I dug up prior to the pipe replacement. This consisted of a loose sub base of broken bricks, rubble etc and a concrete slab that was cracked in several places. On top of this were blue Staffordshire paving bricks. I have also found another suspect gully which I have excavated around it and there are many half and whole bricks with voids in between. Directing a hose in this area causes water to come straight through to the cellar.



I plan to remove all poor back fill and replace with proper pea gravel below the gully and MOT to bring up to ground level.



I then don't know whether to put concrete over the top and slope towards the gullies.

In my mind, if I leave a 12 inch border around the house wall of gravel over the MOT, water will soak through this and into the cellar again.



Any advice is welcome.

 

[a twig]

EDIT: Sorry - hit send too soon!

I assume in your plan you are re-pointing and filling voids etc?

If you have all the drains sorted then I’m not sure where the water source would come from to cause new leaks?

 

[Digger2]

Hi, thanks.

I feel like the voids that were present around and below the suspect gulley have allowed water to be directed straight through to the cellar, as directing water in that area caused water to appear in the cellar almost immediately. Would it not be the case that backfilling with MOT would still be a porous material and allow water in still? Or would the MOT slow the rate of water pass through? The other issue is that the soil is clay and my be slow to absorb water.

 

[a twig]

Sorry, I must be missing something here - isn’t it just a matter of repairing / replacing the gully and thus removing the source of the water that is currently coming in?

By the sounds of it - everything was fine until the pipes and gully failed, so unless your cellar sits beneath the water table in the ground - that should resolve the problem?

 

[Digger2]

The latest problem gully and pipe from it hasn't failed, it's more the concrete around it that failed/cracked allowing water through and then through the loosely packed rubble around and under it.

 

[a twig]

Sorry - end of a long day and I don’t think I’m explaining myself well - so if the gully and the rainwater goods are now fine and there aren’t any voids etc left:

1) where is the water going to come from that will find its way through the cracks and make its way through the cracks, through the rubble and through whatever walls you have into the cellar? Bear in mind a hose directed at a wall is a lot of volume at a much higher rate than rainfall.

2) if you are concerned just about direct rainfall / wall run off coming down on the bit of ground around the base of the wall then as long as your cellar walls are in good nick and the ground levels around the wall are level or slope away then gravel should be fine.

If I’m still missing something photos always help

 

[Digger2]

Ah OK, it's probably the volume of water from the hose that is the issue then as you say. I'll back fill properly and see how it goes.. Thanks for the advice

This is the gulley area in question with the broken bricks mostly removed..