On Dec 12, 1:05*pm, "David Hare-Scott" wrote:
rasik wrote:
Thanks David

We have a brick layer. *So we have a level and string line. *We will
be using engineering bricks.

He/she ought to know about foundations and weep holes too.

I believe I need to water proof the inner layer. *Which dpm should is
best to use? *bitumen?

The foundation has already been built and is adequate. *The foundation
width is 600mm wide. *Both walls will sit on the same foundation so
the passage to the earth is blocked. *Water will not be able to weep
right down to the earth. *Am I correct in assuming the weep holes
(300mm apart) is sufficient if the passage is blocked by the
foundation?

The water must be able to run out and you obviously don't want it to pool on
your patio. *Aside from the inconvenience it will have the potential to
stain. *So where will the water run to? *As the box is narrow you will
probably get away with only having weep holes on the outside but the water
still has to drain somewhere - ask the bricklayer.

D

Would bitumen be toxic to plant life? ISTR we used to be advised NOT
to plant potatoes in rings of tires because they could be/are toxic.
A little confused; anybody have the skinny on this?

HB