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Posted: Fri Jul 11, 2008 6:09 pm
by jbuckler
Need some help!
I am laying a new sandstone patio (3mx4m)which is over an existing rubble filled soakaway (1.5mx1.5mx1.2m deep).
I have limited thickness over the soakaway of 150mm.
For the patio the ground conditions are not too bad so using base of 70mm ballast:cement 10:1 mix with 40-55mm sharp sand:cement 6:1 mix bedding layer.
How do I span the soakaway? Was looking at 5mm thick metal sheeting but this is not cheap. Could I use reinforcing mesh and lay 100mm reinforced concrete cap?
Posted: Fri Jul 11, 2008 6:17 pm
by Slabba.
100mm reinforced concrete cap over soakaway! More than enough mate. make sure you compact the area of the soakaway until refusal, this should be enough in itself, done it many times and no problems but capping it the way your thinking, bomb proof.
100mm mot type1 hardcore compacted,lay the slabs on a wet mortar bed. remember to lay the indian sandstone the correct way up.!!!
goodluck. 
Posted: Wed Jul 16, 2008 9:52 am
by Tony McC
Rubble filled soakaway - I thought we'd done away with these useless constructions!
Anyway, with a width/length of 1500mm, I;d normally suggest a cover slab, but as they are minimum 150mm thick, that's not possible in this scenario. Consequently, I'd look at using a few lengths of HoloRib or similar and then bed the flags directly onto the concrete.
Posted: Wed Jul 16, 2008 8:26 pm
by lutonlagerlout
believe it or not tony ,luton council actually asked us to do a rubble filled one, on their own job!!
when i questioned it i was told that rubble is fine when the ground is chalk,and if they pay me i will whistle any tune they like 
LLL
Posted: Thu Jul 17, 2008 10:51 am
by Tony McC
Nothing, absolutely nothing, ever surprises me about local authorities. They're usually a strange blend of genuinely committed people having a keen sense of public service, with complete and utter eejits.
Why don't us normals use rubble-filled holes as soakaways any longer? Void space. Broken bricks and flagstones generate around 20-30% void space, whereas clean gravel can give 30-50% and storm cells offer 90-95%. More storage for a smaller hole = less digging and less spoil.