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.).

I can see some obvious ways:

(1) Front and back wall level. Hang the lower end of the joist flush
with the wall plate and rest the base of the high end of the joist on
the wall plate. This will require the low end cutting at an angle to sit
properly in the joist hanger and the high end notching to sit onto the
wall plate. Sloping ceiling.

(2) Front wall one block higher than rear. Hang both ends from joist
hangers. Both ends will need cutting at an angle to fit the joist
hangers. Sloping ceiling.

(3) Front and back wall level. Hand the main joist parallel from front
and back wall. Fit a profiled piece of timber above the joist. Simple
hanging, no angles cut, less lateral force on the walls (not that there
should be much anyway). Flat ceiling. Downside (if any) seems to be the
odd shaped roof void which will give a lot of air space above the
insulation at the higher end.

What dos the team think?

TIA

Dave R
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.

Bob