Should I use a soakaway

[wood2e1]

Hi,

We are building a garden office, but our garden is on a slop. Basically the garden is 18foot wide and about 300 foot long, being higher at the end of the garden and lower closer to the house.

The Garden Office will be 16foot by 12foot.

So the back of the shed has a higher ground level than the front, obviously the concrete base is level

What I had in mind, was to dig out the ground behind the Garden Office, to bring it just below the level of the concrete base.

Then have a (french/acro) drain running the width of the office, and connected it to a soakaway.

The area we dig out with be covered with Pea shingle as well, to help with drainage.

Anyway the idea being that the drainage will take surface and rainwater away from the shed/concrete base and slow down the amount of water release.

So really I need to know if this is a good idea? And if it is what size soakaway should i go for? 1m3?

 

[foxhole]

Ok, a cubic metre should be more than enough for a small outbuilding.

 

[wood2e1]

Hi

Many thanks for that.

I was not thinking of connecting it to the guttering of the office, but just to slow down the rain water that hits the garden, and move water from the back of the shed as it falls into the ACO Raindrain Channel Drain - so cutting down the chances of rain water or any water getting into the shed..

It may be over kill, but the garden is on an upwards slope and so I am going to have to cut about 5 metres by 4meters of soil out, down about 150mm !! Just to level out the garden behind the shed and so it is as low as the concrete base, if not lower, depending on how the back holds out

Also I am putting down pea shingle in this levelled area so water hitting it will go straight down rather than across hiting the shed wall and getting in!

As I said I may be over thinking the need. I just don't want water in my office!!

 

[endecotp]

As I said I may be over thinking the need.

It does sound rather extreme lengths to go to to me - not that I am an expert....

Do you currently see streams of water running down the garden past where the building will be? Is the ground particularly impermeable? (Clay?)

 

[wood2e1]

Hi

We don't see alot of water running across the ground there, but further down closer to the house we can see rivers of water running down the patio area and down the side gate onto the road.

And yes there is a fair amount of clay, but not where the shed is or behind it. Or not at the depth we are digging down to.

The main reason for this 'solution' is to stop water going in the shed once built, we will be taking down the level of the earth behind the shed, so that will mean the that the earth is either the same level or below the concrete slab. And we will have a drain running the width of the shed.

So with the soakway it is somewhere for the water to be taken from the shed and possibly slow the water running down to the house. We have also removed grass in front of office and replaced with pea shingle.

The reason for the caution is many years ago a 'building/patio' expert told me that having the patio the same level as the 'damp course' on the house, with a 'French Drain' there will be no problem.. low and behold the wall under the sink is constantly wet!!

So I am taking a belt and braces approach.