Knock down half the aerated concrete wall? Not the whole one:)

[grungarn]

I'm going to take down a lightweight concrete wall and will let half of it remain.
If I take it down with a sledgehammer, it feels like there's a risk that the whole wall or large parts will come down.

Should I use a reciprocating saw and cut it in the middle, or should I attach two planks to the wall where I want to knock it down? Then it should work to fill in what has been chipped off with render and use the planks as a form.

 

[MathiasS]

Lightweight concrete - do you mean siporex? If so, it's excellent for sawing.