play / tolerance in 110mm waste fittings - tweak gradient possible?

[Joamon]

Hello

I am moving my upstairs bathroom and intend on having the 110mm waste pipe running parallel with the joists to the existing soil stack (where I will insert a new branch).

The length of new run is just under 5m (so quite long). This is within BR here.
The available angles from the branches seem to be limited, and 92.5 (87.5) seems to be the closest option for this application (or maybe a 90).

A 92.5 degree branch suggest the pipe should be laid at 2.5 degrees off the horizontal (1:25). (Option A)
I would like to try and lay the pipe to about 1 degree (approx 1:60) from the 92.5 branch. (Option B)

Would there be sufficient play in the branch and or coupler to achieve this for either the solvent weld or push fit variants?
Or perhaps I would be better using a 90 degree branch with such a slack gradient.

Reason for laying the pipe slacker is that I would like to reduce the amount of ‘boxing-in’ (shown green) in the kitchen (the joists are only 7” thick).
Gut feeling is that there will be a little play in the push fits but solvent may be tricky.

Thanks in advance

 

[denso13]

Would there be sufficient play in the branch and or coupler to achieve this

Yes, don't think you'll have a problem with that. At that length the pipe will sag down anyway, just fix it to the required slope.

 

[Joamon]

Thanks denso13 for quick response. Would you suggest pushfit or solvent? or both okay? thanks

 

[denso13]

Both ok, but push fit would give you more play, and is fine at 110mm. Wouldn't use push fit for smaller pipes.

 

[Joamon]

Sound advice, right, best get some pipe in then! Thanks again denso13

 

[Madrab]

As long as it stays within the min fall requirements - 18mm/m fall then it would be fine. Though if I gauge it correctly 1:60 is slightly below that?

Worth noting though that 18mm is the min per the regs and not necessarily the best when it comes to a pipe run being free draining and self cleaning, especially with the lower flush toilet capacities etc these days.

 

[Joamon]

Thanks Madrab, yes you're right 1in 60 is slightly below, and agreed that working to the limit may not always be best idea. Will reflect.