digging out question around house

[shaunjbaird]

Hi. There's a gap around the house and customer wants it filling with pebbles. But before that to dig out what's in it. Some sand and rubble... That's fine.. dig out and fill.. but they're saying they think it should be a foot deep for good drainage. So.. garden slopes a bit to house. As the gap is right next to the house do I have to dig down below foundations? They have said it gets waterlogged there so asking for a piece of plastic to be placed against the house. . within the gap.. then backfilled with pebbles as sometimes it can leak into conservatory.. so if I dig down say 6 inches or a foot?? (Which is best?) Would this provide an adequate place for water to soak down... If so is the project likely to lead to other problems as a result. Sorry if the question isnt clear..I'm not sure how deep to dig or if the plastic laying in the gap flush to the conservatory wall but below the dpc would cause any problems.. I have added 2 pics to an album

 

[Burnerman]

I had a similar issue Shaun.....what I did was to dig out a trench maybe 12" from the house wall, and then use some thinnish flags vertically to provide a sort of water cofferdam - the upstand was 3" above the ground level. All was cemented in.
I excavated down to the house foundations and left the trench open, covering the top with wire mesh to stop the leaves but keep the ventilation there.
It certainly worked for me - the garden level had risen over the years, and a gradual slope was casting water towards the building.
John

 

[shaunjbaird]

Thanks John. Its all patterned concrete so I cant really excavate any new channels. The gap is literally the gap between the house and the patterned concrete. In an ideal world Id just dig out maybe 6 to 8 inches and fill with pebbels and job done, but they want some plastic putting in to be placed in flat against the house itself and then filled with pebbles.. with the aim being to stop water getting into the house.. but that water has to go somewhere.. so if its going straight down, it will be somewhere under the house but right next to the house hence my concerns about drainage and if it could cause issues perhaps with decay/crumbling of the foundations further down the line. I do know building inspector has been in and signed the extension off so Id like to think he would have said something such as ("builder must put in proper soak aways") - Im not the builder by the way, family relative who does gardening and been asked to dig out and fill with pebbles. IM trying to upload a video here

 

[shaunjbaird]

20160109_142823

• shaunjbaird
• 9 Jan 2016

20160109_142831

• shaunjbaird
• 9 Jan 2016

Overall around 16 metres to dig out about 5 inches wide.. but how deep should I go.. and any...

 

[shaunjbaird]

Ive just been looking elsewhere and found that actually my question/concerns are unfounded and generally its fine. So IM just going to go ahead and get it done

 

[Burnerman]

A similar situation to mine - albeit that's a newer house with a much smaller trench!
Ideally you don't want water to run from the path into the trench, and filling the trench with pebbles looks better but doesn't help with drainage in this case. Digging the trench out will help with drying the bricks down below.
If the DPC is where the brick colour changes, then the surrounding path is on the high side.
John

 

[r896neo]

You absolutely dont need to worry about water damaging the footings. The only issue with directing water near footings is creating some sort or flow that could gradually remove material and undermine them.

What your proposing will have no issue.. Lead flashing would be a much neater solution but would be a lot more expense and work.

 

[shaunjbaird]

You absolutely dont need to worry about water damaging the footings. The only issue with directing water near footings is creating some sort or flow that could gradually remove material and undermine them.

What your proposing will have no issue.. Lead flashing would be a much neater solution but would be a lot more expense and work.

Thanks. Any particular depth required. It does flood a bit so I'm guessing at least 8 inches

 

[r896neo]

The lead flashing will stop penetrating water and splashing but if the trench actually fills with water then it will simply flood up behind the flashing. In that case painted on liquid dpm would be best but may not be very attractive

 

[shaunjbaird]

Ok thanks