Garden Wall Project - help required

[spiidey]

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[spiidey]

We're trying to plan the heights of the two walls now we've excavated and measured by laser.

See diagram below.

We're planning on slabbing the 4300mm wide and 3300mm wide sections.

Question: For the bottom section (the 3300mm wide section), can we have a fall on this section of e.g. 1:40 or 1:80 towards the house?

If we can have a fall towards the house, do we need something between the slabs and the house e.g. chips/gravel?

If we can't have a fall towards the house, how should this 3300mm section sit against the horizontal - should it be absolutely flat, or should the fall actually be away from the house?

 

[r896neo]

Where is the water draining to? a drain? running off down the side of the house? As this will obviously dictate where it falls to.

You should never fall paving towards a building unless there is no option.

If its totally flat you'll have a shallow pond??

 

[spiidey]

Where is the water draining to? a drain? running off down the side of the house? As this will obviously dictate where it falls to.

You should never fall paving towards a building unless there is no option.

If its totally flat you'll have a shallow pond??

We have one drain connected to our main house drain - its at one side of the garden - see plan below of our current garden (prior to the landscaping works we're undertaking).

Really looking for advice on what is the best option for us to do with regards drainage so would welcome any advice.

Should we fall the paving away from the building i.e. towards the front of the 400mm retaining wall in the diagram in my previous post?

 

[r896neo]

As i said you should fall it away from the building unless you have no option.

Its very hard to say what you should do without seeing the site.

Do you have a combined foul and stormwater system or are they seperate?

 

[spiidey]

As i said you should fall it away from the building unless you have no option.

Its very hard to say what you should do without seeing the site.

Do you have a combined foul and stormwater system or are they seperate?

How would we check that?

If we fall it away from the house, can we fall it fully towards the front of the first retaining wall?

 

[r896neo]

Lift the manhole nearest the street (maybe on the driveway) and pour a bucket of water down a rainwater gulley that serves only a gutter downspout and see if it comes out through that manhole.

then flush a toilet and see if that comes through the same pipe.

 

[spiidey]

Lift the manhole nearest the street (maybe on the driveway) and pour a bucket of water down a rainwater gulley that serves only a gutter downspout and see if it comes out through that manhole.

then flush a toilet and see if that comes through the same pipe.

Thanks, will do that and confirm.

 

[spiidey]

A few queries:-

1. We need to hire a power saw to cut a curve in the slabs in Image 1 below (slab depth approx 40mm). Do any of the power saws on the attached link from Basically Tool Hire do the job (I'm not sure which is the correct type of power saw to use):- http://www.basically-toolhire.co.uk/hire-equipment/sawing-and-cutting/ . If not, what type of power saw do I need for the job?

2. In terms of drainage, we've still not bottomed this out. Does the proposal in Image 2 below work (green highlighted sections)?

i.e. for the area of the garden that will be at the existing "ground level", we would have a channel running the full length of the garden (14m) that would be circa 200mm wide, 150mm deep and would contain 20mm gravel or large pebbles. The flags on either side of this would then fall towards the gravel/pebbled area, i.e. the slabs beside the house would fall away from the house and towards the gravel/pebbled area, and the slabs next to the 400mm high wall would fall away from the wall and towards the gravel/pebbled area.

3. We need to use concrete under our step section, to help keep the whole step section rigid. We need about 0.6 cubic metres. Is the "Ballast Concrete Mix" from Thistle Timber in the attached link (page 2, under "Aggregates and Sands Bulk Bag") the correct "ready mix" product for us? Or do we need something else? http://www.thistlebuildingsupplies.co.uk/pdfs/price_guide/Price List A5 April 2014 Web.pdf



Image 1

Image 2

 

[r896neo]

You want a 12'' stihl saw as it has a clutch so is safer.

Yes ballast is the right thing.

The area you are draining, including the middle level, is far to big to just hope it will filter away in a tiny strip of gravel.

 

[spiidey]

You want a 12'' stihl saw as it has a clutch so is safer.

Yes ballast is the right thing.

The area you are draining, including the middle level, is far to big to just hope it will filter away in a tiny strip of gravel.

Thanks. So when the area we're landscaping has drained ok in the past, has this been due to the area being almost fully grassed? i.e. now we need something additional if we want to hardstand it all with flags?

We've got the following drain (see pic below), I've just lifted the manhole cover, that is in front of the house in the middle of the site. Can this be used for drainage (or how do we tell whether it can)?

Going to check the stormwater/foul water situation now - we've not been able to do so as we've had skips since last week for site clearance.

 

[spiidey]

We have in fact 4 drains on site:-

3 are marked as "Osma Drain Access" and have a solid, covering that is screwed onto the fitting (i.e. stormwater cannot access these drains without the cover being lifted), and
1 that has a mesh cover and is essentially open to the elements i.e. stormwater can flow into this.

I've marked the location of each of these on site - does this help with our project or are these red herrings / just simply rodding eyes?

Osma Drain Access Drain 1

Osma Drain Access Drain 2

Osma Drain Access Drain 3

Mesh covered drain

Could we install this type of product running right beside the house, running the full length? http://www.waterirrigation.co.uk/ac...eYnY5Fvc3zRVjixFj34NCS8KhOo1b3QwK4aAskV8P8HAQ

Or can we simply install a greater width/depth strip of gravel/rubble in the location from my earlier picture? We could install a perforated pipe at the bottom of this, but I am not clear at all on where this pipe should go/end/run the water to!!!!

 

[r896neo]

ideally you would have a linear drain at the foot of the retaining wall and fall away from the house to it.

lots of good info on paving expert.com regarding drainage so have a read and then come back with any specific queries

 

[spiidey]

ideally you would have a linear drain at the foot of the retaining wall and fall away from the house to it.

lots of good info on paving expert.com regarding drainage so have a read and then come back with any specific queries

Thanks for this. Have now had a good read of the paving expert drainage section.

We were proposing having a linear drain running the full length of the garden (from left to right as shown on the plan in the first picture, with the left being the highest and the right the lowest) on a fall of 1:100, and being connected to the surface water drainage pipes as shown in the second picture.

The drain itself would be a collector/interceptor drain as shown about half way down the page on the attached link, with cobbles/decorative stone on top.

http://www.pavingexpert.com/drain03.htm

Between the house and the drain, there would be paving slabs, falling away from the house and towards the drain. Between the drain and the wall would be a cobbled/decorative stone area, other than where the steps are which would be slabbed.

Does this work?

 

[r896neo]

yep that sounds good.

you could just use a linear aco type channel rather than the interceptor arrangement.