"David WE Roberts" wrote in message
...
Getting closer to wall building time now the weather has warmed up a bit;
if only it would stop raining!

I will obviously need to cut concrete blocks - I will be using the 'medium
density' blocks for external walls with no rendering.
[At least I think the normal ones are described as 'medium density' - it
does beg the question as to what 'dense' blocks are.]
snip

Any idea how much to allow for wastage?
I am not the best cutter of bricks etc.