"Bob Minchin" wrote in message
...
David WE Roberts wrote:
Looking at the roof design (I have looked back through previous useful
threads).

I am considering 6" (150mm) * 3" (75mm) at 600mm spacing.
The span is about 3.5m front to back and about 7.8m side to side.
The proposed roofing is metal sheet.
I am assuming the joists will span the short (front to back) span.

The issue now is how to engineer the slope (I have read that 1/2" per
foot is adequate so a difference of 6" front to back should be O.K.).
snip
I'd use method 3 with half the pitch 1 in 48 should be plenty especially
with steel which should have less tendency for ponding.
ISTR regs for flat roofs suggesting 1 in 80 - I tend to use 1 in 40/50 and
have no problems.
The pieces of taper timber are called firring strips/battens specified by
the length and the timber they are cut from

e.g. N number firring strips ex 3.6m x 50mm x 100mm will give you about 1
:40 fall
N number firring strips ex 3.6m x 50mm x 75mm will give you about 1 :50
fall.

The short sides of your block work will need to be angled to match. Cut
the blocks at an angle and finish off with a course of bricks. These will
be hidden behind the roof fascia.

I intend to put a wooden wall plate all round the top of the wall.
Any reason why I can't use a flat wall with firring strips on the top of the
wall plate to geve a slope and a seal?
It looks a lot easier than trying to cut a very shallow angle in dense
concrete blocks.