Stumps or slab?

The builder is Scottish and learnt his trade back home. Doesn't believe in slabs. Doesn't cost any more than a slab. It's so much more practical this way, I've relocated the ensuite toilet twice - wouldn't have been possible with slab.

 

You may need to nominate finished floor levels (FFL) and retaining during Town Planning ( you do in Perth) so I would assume that you may need to decide now if stumps would produce different levels and retaining than slabs.

 

Thanks Scott and @Westminster, it does look like it is advisable to decide this pre-DA/town planning submission, my architect has said "because the floor level needs to be set at town planning stage which is determined by the construction method. For instance if it’s a raised timber floor, the floor level is higher so that you are not cutting into the ground unnecessarily, equally if it’s a slab you want the floor level just above ground so that you have minimum earthworks."

My understanding therefore is that it is preferable to decide now as the finished floor level (FFL) needs to be decided for the elevations. There will be costs if we change this after DA to achieve the same FFL or alternatively amend the permit (not ideal).

As you can see below, if we went slab it would be pretty thick at the ends of the units.

 

You would only do downturned edges of the slab (ie thick slab) if the was only a small drop. For a larger drop like that you could put in a retaining wall before the garages start and fill with sand and lay the normal thickness slab on top.

I still think if you are allowed to do some retaining in the front setback that you could reduce the height of retaining needed

 

That makes sense, so the FFL would be lower then as there would be some retaining walls and both front and back units would sit lower in the ground? This starts to sound a more expensive option then with more site works and more engineering of the slabs.

It is hard to say at this stage which is a better option. For now we are going with Architect advice of stumps unless there is certainty that slab would be better, hopefully we can find a good builder that can build on them!

 

what was the difference in cost per m2 for stumps compared to slab ?

 

We did a 3 pack on a sloping block using slabs. Proper slabs, not waffle pods.

I prefer a slab in terms of how it feels to walk on downstairs.