Is it because your house has cracks in it? Is it because your neighbour had their house underpinned? Is it because you don’t have time and you need your house fixed NOW? Is it because some random salesperson said you do?
It’s time to have your house assessed properly before you weigh up the options for underpinnings and house repairs.
That black plastic membrane under a concrete slab is there for a reason. Join our #StructuralWhyFile to find out why you need a vapour barrier under a concrete slab in Australia.
Why do concrete slabs need black plastic under them? Well, there are some great reasons. Let’s find out why.
Join me for an inspection of a waffle slab before it is poured.
Check out our inspection of this waffle slab before it is poured. Give it a thumbs up if you’d like to know the 10 most important things to look for when inspecting a waffle slab.
What are the Components of a Waffle Slab?
I had an enquiry the other day.
“What materials are used to build a waffle foundation?”
The materials used to build are waffle foundation are:
Black plastic. This is the damp proof membrane that stops moisture rising out of the ground and into a house.
Waffle pods. These are polystyrene blocks used to hold the concrete in place until it cures. The deeper the pods the stiffer the waffle slab.
Steel reinforcement bars. Steel reinfrocement bars run in the bottom of the ribs and are the ‘bottom reinforcement’.
Steel slab mesh. Steel wires welded into a fabric are placed on top of the waffle pods. These are the top reinforcement of the slab.
Temporary formwork. Timber or aluminium formwork makes the sides of the waffle pod slab until the concrete is strong enough to stand up lby itself.
Water around a waffle pod slab house being built on a reactive clay site is a problem and it’s not an easy fix.
That’s why the Australian standard for footings and slabs AS2870 says that the surface drainage of a construction site shall be controlled from the start of site preparation until the end of construction.
Why? Because it is easier to get good drainage around a waffle pod slab house while it is being built than after the house is finished.
Check out our detailed video on why waffle slabs are so affected by site drainage and what to do about it.