Question for those with Building know-how

Hi all

I've built a raised area in the back garden. I've gone for a wall about a foot heigh, and filled with soil. It comes into contact with the back wall of the house.

It is lower than the damp course.

The wall that I built comes out from the back wall of the house, but within that, I've left about 8 inches between the soil and the house wall, with planks of wood holding the soil back, and rubble in the gap. So soil doesn't come into contact with the house wall, but rubble does. I.e. the rubble is an 8 inch wide barrier between soil and house wall, and in any case the whole thing is (just) below the damp course.

So I have two questions:

1. Will my rubble barrier plus staying below the damp course prevent my project from rotting the mortar of the house wall?

2. How can I hide the rubble barrier to make it look ok, without defeating the purpose of it by filling it with soil?

 

Hi Dave,

The only thing I would worry about is splashback, but that shouldn't be a problem unless you have a leaky gutter.

You can cover the rubble with 20mm gravel to make a kind of french drain, that would look nicer.

 

Thanks Ziggy.

I don't think splashback will be a problem. The overhang of the roof (the eave?) is quite wide, and then there's the guttering, so in all about 16 inches I reckon. That means that in a torrential downpour with blocked gutters, the water should still land on the soil, and then there's the 8 inch wide rubble barrier to cross.

20mm gravel sounds good. I thought about gravel but didn't know if that would provide a means for moisture to carry from the soil to the brickwork.

Would you use smooth pebble type gravel, or the sharp edged stuff? For appearance I'd prefer the smooth kind, if that would still allow appropriate drainage.

 

I think I would have just put a layer of DPM against the house wall.

If your 100mm lower than DPC I dont think you would need to worry, less than that and its not a good idea.

But personally I'd just put the membrane there.

 

Smooth would work, you'll have to dig it out and give it a wash some years later as soil will build up in it.

Saw a nice one round a church I was working on where they had laid flat natural cotswold limestone slabs on top, looked like stepping stones.

That stopped the soil build up from happening so quick.

 

Pete, the level of the soil is only about 50mm below the damp course, but the rubble 'spacer' keeps the soil off the wall. I've also placed planks of wood between the soil and the rubble, to slow down the rate that the soil will naturally wash down when it rains. I know the wood will eventually rot, but I'm hoping that by then the soil will have compacted enough to not move much.

My mate suggested I put some thick plastic down first, and I was going to, but to be honest once I got into the flow of work, I simply forgot. Now if I pull the rubble up, I suspect the soil barrier will collapse and I'll have to dig it all out and do it again. My back's already aching after moving all that earth by hand, so I'm going to chance it

Ziggy, how about if I get some nice round stones about fist size to mellon size, and put those on, then smaller ones to sort of spill over? I think it would make it look a bit like the beach, you know at the high tide line where the rocks accumulate. It would fit in really well with my seaside garden theme which is my ultimate goal.

The one you describe that you saw round the church sounds nice. Got any pics?

 

Hi Dave,

50mm sounds a bit close to the edit but with good eaves I wouldn't be worried.

Like the beach effect, as long as the stones are draining then they are doing the job.

Not got any pics of Inglesham church, it was before digi cams, but here are a few pics on google images.

inglesham church - Google Search