Building Regs Table Incomplete?

[mike42]

I'm sure it can't be the case that there is a mistake in the building regs and far more likely I've not understood this aspect but why are the last four rows of table 2 below missing an Appliance description?

I was trying to find out how big a waste pipe needs to be to take both a basin and (fairly high flow rate) shower.

 

[Dan Robinson]

50mm

 

[Hot&Cold]

I was trying to find out how big a waste pipe needs to be to take both a basin and (fairly high flow rate) shower.

what is the equivalent length of the combined basin-shower waste pipe run?

edit,what is the fall from shower to soil pipe or other drain ?

 

[John D v2.0]

I'm not a pro but a shower won't fill a 40mm pipe even without the correct fall. Basin is the higher risk to pull the shower trap, if you have any vertical sections go with Dan's suggestion.

 

[Dan Robinson]

shower won't fill a 40mm pipe even without the correct fall

You'd be surprised

 

[John D v2.0]

You'd be surprised

 

[mike42]

Nobody know why that table in the regs seems missing a few rows?

So looking like 50mm 8-(. Haven't got the exact route yet but fall will be within the values set in the table for the first 3-4M or so except for a final vertical run of around 2.5M .

Seems strange why 50mm fittings are a lot rarer/more expensive than 40mm (e.g. at screwfix there are 73 at 32mm, 74 at 40mm and only a handful of fittings at 50).

 

[Yorkshirebloke]

Sorry to hijack,
If I was joining to a 100mm, with a separate strap boss for the sink and a separate one for the shower, could they be in 32 and 40 respectively, or would it be better to run one into the other then 50mm to the 110mm soil pipe?

 

[John D v2.0]

That's because most people just go for 40mm. Don't over think it. The lines aren't missing, it's just ditto. 32mm wastes are complicated to design.

 

[John D v2.0]

Sorry to hijack,
If I was joining to a 100mm, with a separate strap boss for the sink and a separate one for the shower, could they be in 32 and 40 respectively, or would it be better to run one into the other then 50mm to the 110mm soil pipe?

If you have space just run in separately. Depends on what's convenient.

 

[Yorkshirebloke]

Offf perfect! Separate into the soil pipe is very much easier. For the cost of an extra strap boss it makes it really easy.

 

[Hot&Cold]

Nobody know why that table in the regs seems missing a few rows?

intentionally left blank

Dont forget any BS is the absolute minimum quality allowed,some people think its ok to install to the absolute minimum standards.
some people avoid all minimum standards,aka bernard coil adhock install

 

[Dan Robinson]

The standards are also riddled with errors and some woefully out of date. As O&C says, treat them as a minimum.

 

[John D v2.0]

To clarify to the op, the approved documents are just an example of how you might meet the building regulations.
The actual regulations just say something vague along the lines ofof y should take the waste away safely without blocking or causing a health hazard.
What you're trying to avoid here is pulling the trap or draining from one branch into the other.