The Brew Cabin

Posted: **Sat Mar 21, 2015 8:49 am**

I want to lay a path around the perimeter of my garden plus a patio. I've measured up and am looking at around 140 sq metres of surface area. Most of the ground is very uneven top soil and, even though I know it is going to be expensive, I want to do it once and properly.

I've ordered Tony's book but based on what I have read on the website and discussed with people, I'm thinking of the following order of layers:

1. Hire microlite excavator and dig down around 500mm from final top level
2. Lay 100mm of sub-base (any recommendations of what to use? Also, what quantity - I'll need 14 to 15 cubic metres but it seems to be sold by weight so I'm finding it hard to see what I need)
3. Membrane (any recommendations?)
4. Concrete. I intend to get this delivered ready-mixed and was thinking of a depth of 300 to 400 mm, so somewhere between 40 and 60 cubic metres overall. I understand it is provided in different mixes. Which should I go for?
5. Mesh. Most neighbours have really bad cracks and movement in their paths/patios. But one guy used builders from Italy and his paving/path still looks perfect after over 30 years. He said his builders did what he had always seen done in Italy and put a steel mesh in the middle of the concrete to stop movement. Is this a smart thing to do?
6. Lay paving on top of dried concrete base using sand/cement
7. Expansion joints: the longest stretch of path will be 32m, with others of 19m, 15m and 14m. I assume I'll need to use expansion joints. Is 6 metres about the right distance?

I'd be very grateful for any advice on the approach. Many thanks

Posted: **Sat Mar 21, 2015 7:19 pm**

A 500mm dig on a patio Using reinforced concrete sub base will last well over 30 years but it sounds like over kill to me.
The most you'll need to dig off is 200mm.
Standard patio setup would consist of a layer of geotextile membrane, 100mm of compacted type 1 aggregate, 25 - 50mm of mortar then the thickness of the paving that you are laying.
your friends paths and or patios that have subsided probably have no sub base, have been laid on sharp sand, spots or whatever.
Your patio your choice but the money that you save on your sub base would be better spent on the materials going down on top.

Edited By GB_Groundworks on 1464305436

Posted: **Sat Mar 21, 2015 7:44 pm**

Massive overkill . Go for the spec as sy says and you won't go wrong robbo.

Posted: **Wed Jul 22, 2015 3:32 pm**

Hi all,
Work is finally in progress. Anyone know where in the West London area does a geo-textile membrane? Needed for about 30 sq. metres.
Builder is telling me I need wire mesh fror where I might drive car. Any recommendations on gauge and where to get it?
Would Selco or Wickes have this stuff?

Thanks, Rob

Posted: **Wed Jul 22, 2015 3:36 pm**

Got any pictures Robbo. Sounds like an interesting project, would be good to see your progress.

Which area of West London are you?

Steve

Posted: **Wed Jul 22, 2015 5:36 pm**

I missed this post originally (dads 70th burfdee)
sounds like huge overkill in the OP

if you are going to drive a car on flags be aware that tyres can cause marks

if you use proper mesh builders merchants will sell it

I would use A393 but it has to be encased in concrete or it will rust

the geotextile is sold pretty much everywhere but unlikely to get the proper stuff in DIY sheds

we use
http://www.sde-civils.co.uk/civils

for ours but not sure if you can buy such a small amount

if you were a bit more local I would sell you 30m2 for Â£35 but you arent so I cant

you need non woven for stabilisation

cheers LLL

Posted: **Thu Jul 23, 2015 12:09 pm**

Thanks all for the advice. Will get some pictures posted when I understand how to get them on here.

This is all I can find for geo-textile membrane: https://www.selcobw.com/gf-609-geotextile

Builder obviously is telling me I don't need it as I'm slowing him down on that section.

I'm going for laying in the following order:

- Membrane
- 20 mm Type 1
-10 mm concrete into which I'll put the mesh (thanks Luton for the A393 recommendation)
- Mortar - approx 15mm for setting the 24mm thick paving

Rob

Posted: **Thu Jul 23, 2015 6:29 pm**

i guess you mean 200mm of type 1 ,100mm of concrete and 15mm mortar?
LLL

Posted: **Thu Jul 23, 2015 8:19 pm**

Sounds like you have spent a lot of time planning this. I would strongly advise against using a concrete base if you are planning to install natural stone paving. You could open yourself up to a lot of problems. Anyway it sounds like you are already well underway. A 15mm mortar bed is very tight, especially on an unforgiving sub base material like concrete. What is your paving material?

Posted: **Thu Jul 23, 2015 9:24 pm**

Yes LLL. I still think in cm but your measurements are right.
LSP - they are natural stone (25mm) - Kandra Grey from CG Edwards in Hertfordshire. Your comments worry me but it's way too late. I have a concrete truck coming on Tuesday. Is there any mix that you'd recommend. Builders have told me 25N/mm...if that means anything to you.
Geo textile membrane went for a "burton". I was out buying concrete blocks for a wall foundation and they decided to compact the Type 1 without putting membrane down. Very annoying but relationships are already strained and I'm in fear they'll walk leaving me stranded if I insist.

R

Posted: **Fri Jul 24, 2015 8:52 am**

Sorry not trying to worry you but just want to point out a few issues before its too late.

1. I am staunchly against using a concrete base to lay natural stone paving on. In MY experience stone paving laid on a concrete base is prone to leaching. I am not saying its guaranteed but its a good possibility. The following picture is of sawn kandla grey laid on a concrete base:

2. You said the concrete is coming Tuesday. Is it not too late to cancel and use MOT type 1 instead?

3. Calibrate Kandla grey will have a thickness tolerance of +/- 5mm. Its also highly likely that the concrete base wont be spot on. This will mean that in places your bed could be 10mm or even 5mm!!!. Its going to cause lots of problems.

4. On a bed of 15mm the mortar is going to have be wet to get any decent adhesion or strength. There is going to be moisture and wet mortar getting squeezed through the joints causing picture framing. Could be a real mess

5. IF it is too late and you are stuck with the concrete at the very least I would be allowing for a 50mm bed of mortar, at least that would give you some margin for error

Sorry to put all this on you but I would review what you are doing and consider a re-think even at this late stage

If you need to chat about it drop me a PM with your number and I will call you

Steve

Posted: **Mon May 23, 2016 12:58 pm**

Well almost a year has passed...and the job is not finished

I had a difference of opinion with the builders about their ability to draw a straight line and we parted company at the end of last July.
What I now have is the base I wanted everywhere I wanted it - 200mm Type 1 and 100mm 30N semi-dry concrete.
So, I now have to find someone who can lay mortar and the slabs on to the base. The sections I want to do first total around 80 to 90 sq. metres. Minimal cutting of the Kandla Grey slabs is needed as I've designed the base size to take account of slab size.
Does anyone have an idea of what kind of price I'd be looking at and if there are any recommendations in the West/North-West London area?

Many thanks

Posted: **Thu May 26, 2016 7:12 pm**

I can recommend loads in that area but would like to see the state of play before I do
Are you able to post a few piccies
Steve

Posted: **Thu May 26, 2016 10:03 pm**

we are busy till next year now but as said last year massive reservations about laying over concrete
I doubt you will find anyone to do it this summer
if you do I would expect to pay around Â£30-35 Per metre labour only
LLL

Posted: **Fri May 27, 2016 12:36 am**

it won't be but if the concrete was finished correctly and sealed/cured id very much doubt you'd get any leaching.

cookie likes to lay on a cbm base with an sbr bond bridge

The Brew Cabin

Garden path : novice post