There is a new estate just around the corner from me and I keep seeing mountains of styrofoam boxes and then they disappear !!!!
They are using them in the slab for the house to use less concrete !!
Today I actually lucked into a site that was just about to lay the concrete so i could see what they are doing and talked to one of the guys about it.
In the past they would dig trenches and concrete would go down into that and form "footings" but now they use the styrofoam, you can see it effectively creates a trench by having gaps inbetween the boxes.
hard to see here but in those gaps is also reinforcing, then on top is the reinforcing held up by those plastic cup thingys.
interesting idea and one i will be doing to save on concrete as when you think about it its really only the outside edge that is taking any weight, it won't matter anyway as the reo will maintain the strenght across the concrete.
you could just lay footings and brick onto that but you would end up with dirt underneath, i'm thinking if i lay a 100mm slab but have in the center 50mm of stryo WITH GAPS (where there is no weight except the wood storage) then i may save 30-50% of my concrete need.
