Bathroom plumbing

Hi all
We have gutted our cottage as we are in the process of joining two together. The new bathroom will be above the kitchen. We are planning to fit a loo, sink, shower and bath in the bathroom and a sink and dishwasher in the kitchen.
I'm planning to take the waste from the shower and sink together down a 40mm pipe and the bath down another 40mm pipe. At what point can they join the 110 waste from the loo before it goes underground?
what are the relevant building regs?
Does this look like a good plan?
sink shower loo bath | | | | | | | | | | (_______(_______40mm_____| | | | | | | | | | | | sink dishwasher | | | __)________) | | | | | |40 mm | |_____|_______ |_______________to underground waste
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Try and keep the bath and shower waste together, because the difference in height between the sink waste and shower tray waste will give problems of flow back. Yep. The sink may empty into the shower, then flow away down the pipe.
A think a better idea, is to make the outflow pipe a decent diameter (50mm) to take all three appliances and try to keep the running level toward the outside stack as steep as possible and with the shower tray at the highest point, and if it's behind a deep inline trap (110mm running trap), it will prevent the backflow from all the appliances.
The difference in waste outlet height between the appliances is your biggest problem, but is easily overcome by either keeping them all separate, or by putting the lowest to the floor at the highest point on the under floor outflow pipework.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I would suggest that you consult your local authority on the regulations. What you propose looks non- standard.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Nick Brooks wrote:

Looks basically ok to me. Check the charts on the Hepworth site as to what can be combined with what at what slope.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
BillR wrote:

All good stuff. There are some regs to do with distances between joints and minmimum and maximum falls on the pipework, but the basic layout is sound.
You will need a vent pipe or durgo type air admittance valve somewhere in the system.
Most halfway competent plumbers will know the rules, or ask a competent architect to clue you in - or indeed ask the building inspector.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

110mm below for a 100mm stack, 250mm for a 150mm stack. I think if you use two standard connectors you should be ok, but the soil junctions with holes for 40mm pipe look illegal.

on www.odpm.gov.uk IIRC.

You could squeeze the 40mm waste between the soil stack and the wall, to join into the bath waste.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Your design seem fine as you are carrying out a one pip system. Jest make sure you connect your 40mm bath waste to the lowest point in the branch.....then you can run your 110mm for pan and use the outlet above the 110mm on the branch to run your 32mm waste for basin. Doing this will help you from getting any back flow as there are no cross connection if you get my drift. You can if you so wish run any shower waste and simply connect to the 40mm bath waste. PLEASE MAKE SURE YOU PUT IN ANY RODDIN EYES. DO NOT RUN WASTE INTO BASIN USING 90 DEGREE BENDS USE APPROPRIATE T AND INSERT RODDIN EYE JUST TO COVER ANY FUTURE MAINTENANCE PROBLEMS. IF YOU REQUIRE ANY ASSISTANCE THEN E-MAIL ME ON snipped-for-privacy@AOL.COM
REGARDS Keith
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.