jfb Posted February 13, 2020 Share Posted February 13, 2020 I have a toilet and shower in a small downstairs room with a 110mm swept bend finishing 35mm over the top of slab. On top of slab I have 50mm insulation and 25mm tiles. Can I use a 110mm 92.5 single branch 92.5Deg 2 Boss like this with the toilet pipe into 110mm and shower waste into boss at same level? What about using one like this with the shower waste entering below the toilet waste? Is that allowed by building regs or is there too much danger of toilet waste entering the shower waste? Link to comment Share on other sites More sharing options...
ProDave Posted February 13, 2020 Share Posted February 13, 2020 Surely both are way too high unless you are going to have the shower up on a platform? 1 Link to comment Share on other sites More sharing options...
Temp Posted February 13, 2020 Share Posted February 13, 2020 (edited) 2 hours ago, jfb said: I have a toilet and shower in a small downstairs room with a 110mm swept bend finishing 35mm over the top of slab. On top of slab I have 50mm insulation and 25mm tiles. Can I use a 110mm 92.5 single branch 92.5Deg 2 Boss like this The following assumes the sweep bend has a push fit socket on it. I looked at part SY405 (87.5 Degree Five Boss Branch - Push-fit Socket - Spigot) on Marley web site.. https://www.marleyplumbinganddrainage.com/products/soil-systems/pushfit-soil/ The 110mm branch is 175mm from the bottom of the branch connector. The male on the bottom goes about 60mm into the socket of the swept bend. So I think the 110mm branch would be at 175-60 = 115mm above the top of the sweep bend. So the 110mm branch would be 35 + 115 = 150mm above the slab or 150 - (50 + 25) = 75mm above FFL. The WC pan connector is about 180mm above FFL so I think it works for the WC. The branch might even be too low if the WC pan is very close to the stack - you might even need to raise the branch a bit. Best check my maths. Aside: 50mm insulation isn't much. Edited February 13, 2020 by Temp 1 Link to comment Share on other sites More sharing options...
Temp Posted February 13, 2020 Share Posted February 13, 2020 (edited) 2 hours ago, jfb said: with the shower waste entering below the toilet waste? Is that allowed by building regs or is there too much danger of toilet waste entering the shower waste? I think it's ok if they are at right angles. Not allowed to have them opposite (opposed) each other. Edited February 13, 2020 by Temp Link to comment Share on other sites More sharing options...
Temp Posted February 13, 2020 Share Posted February 13, 2020 2 hours ago, ProDave said: Surely both are way too high unless you are going to have the shower up on a platform? +1 I think the centre line of the lower boss would be about 40+35 = 75mm above the slab. That's at the FFL. The McAlpine ST90xxx-70 trap has the centre line of the outlet pipe 35mm below bottom of tray. There is a slightly lower one but I think it only has a 25mm water seal rather than 50mm. So you would need a platform at least 35mm high plus whatever fall is needed on the pipe run. Link to comment Share on other sites More sharing options...
jfb Posted February 13, 2020 Author Share Posted February 13, 2020 thanks temp - i'll have to have a closer look at the measurements when I get a chance. I had assumed I would need a small step up to the shower which is fine - I just want to keep it to the minimum. When slab and swept bend were put in a while ago the plan didn't include a shower. I appreciate that 50mm of insulation isn't much but it is an insulated limecrete slab already. And yes the swept bend has a female socket in the room so that helps. Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 14, 2020 Share Posted February 14, 2020 (edited) You can put a pipe boss on the stack before fitting the branch for the toilet why lift the shower if you don’t want to. Dont comprimise if you have come this far get it how you want it. Plan where you want your shower, chop a trench in the floor and get the pipe work in set it to the correct height to have the shower you want not the one you think you have to have. Edited February 14, 2020 by Russell griffiths Link to comment Share on other sites More sharing options...
jfb Posted February 14, 2020 Author Share Posted February 14, 2020 I don't think I have the height to get the shower to floor level. The bend ifits very closely to the existing pipe/inspection chamber just outside the building so no room to drop in a boss any further down. There is no stack to speak off just the bend into the inspection chamber. Link to comment Share on other sites More sharing options...
JFDIY Posted February 14, 2020 Share Posted February 14, 2020 I think Russell is suggesting you can put a strap boss on the current pipe/bend and solvent weld it in place to serve the shower. Position at a height to suit you and not compromise. Link to comment Share on other sites More sharing options...
Temp Posted February 15, 2020 Share Posted February 15, 2020 (edited) Can you put a strap boss on a swept bend? Thought all strap on boss are designed for straight pipe. There is also a minimum height for the lowest connection in the regs but that might not be an issue. Edited February 15, 2020 by Temp Link to comment Share on other sites More sharing options...
JFDIY Posted February 15, 2020 Share Posted February 15, 2020 The sides of a swept bend shouldn't vary much in flatness/profile compared to a straight pipe, the inside and outside would be obviously a different kettle of fish. Don't know if it'd be 100% to regs but it'll all be hidden anyway. Link to comment Share on other sites More sharing options...
jfb Posted February 15, 2020 Author Share Posted February 15, 2020 I assumed you can't put a boss on a swept bend and it is mucked in anyway so couldn't get a strap around it if I wanted to. Hence trying to work out the lowest place I can get the shower waste in above the bend. Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 15, 2020 Share Posted February 15, 2020 I was thinking more about one of these. Link to comment Share on other sites More sharing options...
Temp Posted February 15, 2020 Share Posted February 15, 2020 (edited) @jfb has a socket in the floor so has to be a male fitting above it. The second photo in the OP is about as low as physically possible because it has a boss that will end up only mm above the top of the socket. Edited February 15, 2020 by Temp Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 16, 2020 Share Posted February 16, 2020 15 hours ago, Temp said: @jfb has a socket in the floor so has to be a male fitting above it. The second photo in the OP is about as low as physically possible because it has a boss that will end up only mm above the top of the socket. Any fitting can be turned into a male fitting with the addition of a short length of pipe. Link to comment Share on other sites More sharing options...
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