Question for the experts!

[lenny]

What fall should 100mm w/c waste pipe have per metre? Should the fall be increased to compensate for 3 - 90 degree bends? (The total length from the WC to the stack is about 3.5 metres)

Thanks

 

[johngee]

im no expert but i thought it was 18mm per metre, or min of 10mm per metre.

 

[wnjswozo]

1in4 fall

 

[REDSAW]

1in4 fall

PARDON,
4' run with a 1' drop?.

the question was for an expert, i'm no expert, but i think you will find that it is 15:1000 that is 15mm per meter, 3.5 x 5 = 52.5mm.
too steep and it starts to block as the pipe becomes non-self cleaning. i believe.

 

[WHPES]

Too shallow and it starts to block, too steep and it draws water out of the traps due to suction.

Part H of the Building Regulations states 18mm per m minimum which you should take as the mandatory requirement.

When erecting a soil stack the angles are predetermined by the sockets on the branches in the stack.

 

[NickH]

1 in 60 , or for me, the width of my thumb under my 4' level. If its too steep the "liquids" will run away and leave behind the "solids".

 

[TGor]

Sorry dunno what the regs say but 1:40 for a 100mm is a good guide ..thats about 1.5 deg. Junctions are usually at 92 deg .. 3 bends seems a lot in a 3.5m run but no need to compensate just make sure pipes are cut straight with no obstructions.

 

[REDSAW]

1 in 60 , or for me, the width of my thumb under my 4' level. If its too steep the "liquids" will run away and leave behind the "solids".

thats what i was saying, too easy to think that the quicker it gets rid of the waste the better, its not, its the opposite hense 'self cleaning'.

 

[learningplumin]

Hi, 3- 90 degree bends?
135, degree at least?

FORGOT, SORRY!
No expert, just love plummin, and learnin plumin.
Thanx.

 

[REDSAW]

Hi, 3- 90 degree bends?
135, degree at least?

FORGOT, SORRY!
No expert, just love plummin, and learnin plumin.
Thanx.

wtf u on?.

 

[learningplumin]

HI. redsaw, thought the 90, bend would be too steep?

Not sure, but if a 135- degree angle, is curved based, then less resistannce than 90-degree?
AS I say learnin!