Hi all,

I am planning to convert a single-skinned, block-built outbuilding into
a workshop. I have read many other posts about this type of project,
and know roughly what I need to do, but I have a few specific
questions:

1) The building has a rough concrete floor, which I plan to raise
slightly (about 5cm), and level off. I need about 0.5 m^3 of concrete.
How do I convert this volume into the required bags of concrete, sand
and ballast? Are there tables anywhere that I can use?

2) I notice that cement is sold in 25kg bags, but sand and ballast are
typically sold in `bags', or `jumbo bags' (big canvas things), with no
indication of their weight/volume. If I am ordering material to mix
concrete in a specific ratio (e.g., 1:3:6) do I use `bags', or do I
have to convert a sand `bag' into the appropriate weight to match the
cement weight, and order by that quantity instead? Is a `jumbo bag' a
specific number of `bags'?

3) I am going to dry-line the walls. I have seen two different
approaches to putting in the membrane: some people state that it should
be placed next to the wall, underneath the battens, and others state
that it should go between the battens and the facing material. Which is
correct, or should different methods be used for different purposes?

4) Facing material seems to be sold in widths of 600mm, or 1200mm. If I
use 3x2 battens, fastened at 600mm centres, then the gap between the
battens is about 520mm. I'm curious as to why insulation material isn't
sold in these widths, at least for common batten sizes?

5) Insulation: should I use mineral wool, or polystyrene? I haven't
been able to find any meaningful comparisons, so what factors determine
which is the better option?

thanks,

dan.