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Posted: Mon Mar 03, 2008 3:07 pm
by Bob_A
I’d like to create a blocked paved area in the middle of a lawned area.
During the summer months I want to place an above ground swimming pool like this one on it.
http://www.splasherpools.com/proddetail.asp?prod=56949
It’s has a diameter of 15’ and height of 42" and holds 17570 Litres of water.
Is type1 ok for the sub base and sharp sand for the bedding layer. How thick should these layers be and lastly do I need a geo fabric. If so at what layer would it go.
Thanks in advance
Bob
Posted: Mon Mar 03, 2008 11:56 pm
by matt h
subbase and lean mix was recommended earlier cos of weight 1itr water equals 1kg approx in weight
Posted: Tue Mar 04, 2008 8:07 am
by Bob_A
In my thread created when I was going to use flags someone said place them on 100mm of leanmix, no mention of using a sub base.
Does that mean I can lay the blocks in the same way?
Thought I'd need a sub base?
Posted: Tue Mar 04, 2008 9:08 am
by matt h
read main site!
Posted: Tue Mar 04, 2008 10:40 am
by Rich H
18 tonnes is a lot of weight, even over 15'. The foundation method and depth will be largely determined by the substrate.
You should use a sub-base of DTP Type 1 regardless of what you put above, preferably on a fabric if you suspect minor movement in the future from below (e.g. on clay or with a lot of tree roots). At least 100mm, I'd suggest.
For the bedding course, there are lots of ways you could do this but I'd favour a rigid rather than flexible approach as the weight will be concentrated in one place. You might think about concrete with weld mesh.
Posted: Tue Mar 04, 2008 10:49 am
by Bob_A
matt h wrote:read main site!
Please be aware I'm a newbie.
I've got Tony's book and I've spent lots of time reading and enjoying the main site (which is great!) but one thing I lack is experience in making judgements.
I can understand the mechanics of creating a patio where only light foot traffic is expected and I understanding the need to create a structure that needs to withstanding the movements of heavy vehicles.
I'm just not sure about 17.5 tonnes of evenly distributed static water.
EDIT
Thanks Rich for your reply, most appreciated.
Didn't notice it as I was busy typing the above!
No tree roots but some clay present so will use a fabric.
Any other suggestions gratefully received. 
Posted: Wed Mar 05, 2008 6:15 pm
by Tony McC
I think you have to be guided by the condition of the sub-grade. If you have firm clay, then a 150mm sub-base of DTp1 might be adequate, but if there is any doubt, it may be a better idea to use a 150mm layer of permeable (no fines) concrete, cover this with a construction geo-textile (NOT a weed barrier), and then your block paving as per normal.
If you use a 'normal' concrete, then you MUST make provision for the laying course to be drained, especially as it is likely to receive a regular dousing from the summer pool. If the laying course becomes saturated, it will move and take the blocks with it. Take a look at the Laying Blocks over a Base page.
Posted: Thu Mar 06, 2008 7:57 am
by Bob_A
Thanks Tony. I'm going to seek advice about my soil before going any further.