Waterproofing a building below ground level?

[perky416]

What do you mean by step?

The wall will be full height on the outer skin, and only 2 blocks high on the inner skin.

I was going to build both skins straight onto the flat top of the foundation exactly as per my picture. Is this correct or the wrong thing to do?

 

[freddiemercurystwin]

It's correct if you don't mind it being there. If for instance you were going to line the inside with insulation and plasterboard it'd get in the way but as you're not then it doesn't seem to be a problem.

 

[perky416]

Ohhh im with you. Yeah it will be in the way lol. Im going to plaster inside. To bring the outer course level with the inner i was going to use 100mm battens and build a stud wall, effectively on top of the inner course. Screw the plasterboard to the battens and use adhesive at the bottom of the board where the block is.
Im likely going to clad the exterior rather than render it. I can plaster, but have never rendered, i didnt want to risk it looking rubbish and given i was quoted 1k to plaster a 10sqm ceiling recently, im guessing to have the whole build rendered (around 50sqm) will cost a fortune in comparison to cladding.

 

[bolst3r]

how did you get on with your building? I'm needing to excavate for an outhouse for similar reasons too, and i'm weighing up the pros and cons of each solution. My building was going to be a timber structure on a concrete slab, I was thinking of a slightly different method as I have enough surround area to create a trough all around it (50cm = front and sides, 20cm back)

So something like this... any thoughts?

 

[freddiemercurystwin]

The above only works if you've dug a test pit over the winter and seen what the water table does. Even then it's not foolproof.

 

[bolst3r]

back to the drawing board on my build then. As it was going to be a timber construction on a concrete slab it seem more problematic?