Laying gravel - drainage concerns

[CW85]

Hello guys,

First I must apologise in that I am a total novice and have just come across the site. I am new to all of this, as such I may not be able to provide the best answers to any resulting queries you may have. The following may be quite lengthy, but I'm trying to give as much detail as i can in my laymans terms - I have attached a picture to try and help

The rear garden of our house slopes towards the house (the house is built on a mild downwards slope). The garden itself has always been grassed since we moved in a few years ago. During even moderate rain-fall, although the turf would not water log (there would be no puddling of water or anything that severe) it would end up retaining water close to the surface and any foot traffic would churn the garden up. It would often take a few days of clear weather to dry out fully.

The only area that remained solid under foot was a small area of gravelling by the back patio doors that the previous owner had put in. As such I recently decided I would gravel over the area we most from the back door to the garden shed.

I started skimming the surface vegetation and discovered the garden soil comprises about an inch of top soil and beneath that clay, which explains the issues with the soil churning up easily. When lifting the existing old gravel I found that it had simply been poured out to a depth of no more than 2 inches over weed membrane laid over clay soil.

I spoke with a friend who had done some gravelling in his garden and he recommended "putting a layer of aggregate down as a sub base and whacker plate it first" to make a more solid and better draining gravel area. Given that the old "gravel on membrane" seemed to have held up okay, this seemed like good advice to me in making the job a bit sturdier

As such, thus far I have dug out the relevant area down to about about six inches in total (still clay at this point). I have laid out a border between the lawn and proposed gravel area using old house bricks that has been cemented in place. I have then laid out geo-textile landscaping fabric and yesterday took delivery of about 3.5 tonnes of Type 1 Aggregate.

Yesterday I was able to barrow about a tonne of this out over the landscape fabric, covering the whole area. Thus far I haven't levelled it out or anything as I still have loads left to barrow in and was going to level it prior to compressing it with a whacker plate. As such, at present some parts have about 2-3 inches while others have minimal coverage and there area quite a few dips and delves in the surface.

It has rained moderately pretty much throughout the day and at first, things held up fine, however now I am starting to see puddles forming in the dips and delves in the surface of the Type 1 which has led to me wonder about drainage.

I had planned on having about three and a half inches of compacted Type 1 with one - one and a half inches of decorative gravel laid over the top and assumed the materials involved would absorb/percolate rainfall and at that depth would be sufficient to avoid any risk of flooding? Am I right - am i just seeing puddles due to the lack of a uniform level or should I stop what I am doing and consider digging some drains?

Thanks for your help, and please bear with me!

Picture:


http://i1179.photobucket.com/albums....p3y.jpg

[jell1234]

I am also only a novice in this area, but since nobody else has replied yet I thought I'd give my opinion. Please jump in and correct me if I'm talking nonsense, anyone!

From the reading that I have done on this web site, I'd have thought that compacted type 1 under your gravel is precisely what NOT to do if you're trying to improve drainage. The type 1 is designed to contain no voids so there is nowhere for the water to go, and the compacted type 1 acts as an impermeable barrier. (if installing permeable paving a different type of sub base is used that has a greater amount of voids - see pages here http://www.pavingexpert.com/permabl1.htm)

Whatever you do, I don't think you'll get far until you address the problem that you've got too much water falling on an area of clay soil, so presumably you need to consider some sort of extra drainage to get rid of it.

[lutonlagerlout]

I have built drives with gravel over type 1 wacked and although not free draining water does drain through it

however if you are on hard clay then really some kind of channel or land drain would be better going to a suitable soakaway

LLL

[CW85]

Thanks for the responses, bit of an update.

I haven't been able to lay out any more of the Type 1 due to shift work and pants weather. We've had a few days rain and what I've noticed is that the water is collecting on the surface of the Type 1 in areas where I have only laid it very thinly, or laid it unevenly. I've been out and levelled out these areas and that seems to have improved things no end. In addition the water collection that I am getting is nowhere near as bad as it was when the area was lawned over.

I take on board the point that putting in some drainage would help, however Im struggling to work out how i could do it. I have considered drains however the only pre-existing drains seem to be for foul water and are back towards the house (which i am not keen to direct the water towards) and are sunk into concrete which would make it difficult to tap into them (SEE HERE). I did consider a soakaway a while ago and dug a test hole on the other side of the garden but found that it just never really drained away.

My next thought was to adjust the way i level the gravel dressing to create a camber so as to try and encourage water away to the edges and away from foot traffic. The only issue i have with this is that although it would let me direct the water away from the house, it would end up flowing onto the driveway (the area behind the wooden fence on the picture in the first post) which I share with my neighbour.

As stated, the original plan was to have about 3.5 inches of Type 1 then top dress it with decorative gravel. Would it be beneficial to the percolation of the water if I left the existing inch or so of Type 1 down but increased the depth of the gravel layer instead in order to give the rainwater further to travel down?

Thanks for the help