Are waffle slabs any good or are they a disaster waiting to happen? Should I invest more money in my build to get a stiffened raft slab?
Hot topic, this one... There's obviously been plenty of worry about these lately with builders like Metricon having to pay up over slab heave issues and the many problems that causes - particularly an issue in the outer fringes of western Melbourne where a lot of people are reporting problems with new houses built on reactive soil sites.
We put this to our resident housing inspection guru Jerry Tyrrell and his advice is that if they're "correctly designed, inspected and certified these should be fine".
Jerry's advice is that you should seek the advice of an independent engineer experienced with these slabs, and make sure you're clear about the soil classification and site conditions on your site.
This is pretty much what we've heard on this topic too - waffle raft slabs can be used without problems, but it's important that they're only installed on appropriate kinds of soils, and that they're built correctly. Definitely worth getting an engineer in to advise if you're not sure - nobody wants the kinds of problems that come with a faulty slab.
The BUILD team
With thanks to:
Architect, Building and Timber Pest Consultant | Tyrrells Property Inspections