Roz Posted August 19, 2019 Share Posted August 19, 2019 Hi Hub! Pics attached. Our SIP studio is obviously made of SIPs but the floor is made of timber cassettes with rockwool insulation in them, caberdeck on top and fireboard on the bottom. The whole thing is sitting on jackpad plinth foundations. Our waste pipes were installed early and there was a bit of guesswork about where the soil pipe would end up. It's currently coming up just to the left of where the toilet will sit. I've just cut a hole for our shower waste and I'm wondering how best to connect the two. I was thinking a flexible connector... down through the fireboard or out through the side joist (double thickness... 4 inches maybe). There's not much access underneath to connect the two but we can scrabble around and maybe shift a bit of earth (but not much) Anyone got any thoughts on how they would do this and what I need? Link to comment Share on other sites More sharing options...
Russell griffiths Posted August 19, 2019 Share Posted August 19, 2019 oh God, don’t use a flexi. Link to comment Share on other sites More sharing options...
PeterW Posted August 19, 2019 Share Posted August 19, 2019 Step away from the flexi.... turn the shower waste to point at the drain, pair of 45 bends to drop the level and straight into a strap boss ... Link to comment Share on other sites More sharing options...
Onoff Posted August 19, 2019 Share Posted August 19, 2019 9 minutes ago, PeterW said: Step away from the flexi.... turn the shower waste to point at the drain, pair of 45 bends to drop the level and straight into a strap boss ... With strap bosses: Are they always meant to solvent weld to a 110mm soil? How well will brown PVC soil pipe solvent weld with regular solvent weld? Brown always seems a bit more 'rubbery" than black or grey pipe. When I went from grey solvent weld to brown PVC I used pvc gap filling cement after roughing up all mating surfaces with sandpaper then cleaning with IPA. Link to comment Share on other sites More sharing options...
Tennentslager Posted August 20, 2019 Share Posted August 20, 2019 8 hours ago, PeterW said: Step away from the flexi.... turn the shower waste to point at the drain, pair of 45 bends to drop the level and straight into a strap boss ... If your short of space one of these might help. Fitted on recently and you only need room to drill into the waste pipe. The boss slips into the hole and it locks in place by placing a tool (supplied) in the hole and twisting it. This mechanically locks the boss to the drainage pipe. Do you have room to fit a couple of these on top of your waste pipe? Link to comment Share on other sites More sharing options...
PeterW Posted August 20, 2019 Share Posted August 20, 2019 9 hours ago, Onoff said: How well will brown PVC soil pipe solvent weld with regular solvent weld? Brown always seems a bit more 'rubbery" than black or grey pipe. Its fine and using a self lock boss like the one @Tennentslager listed then you have no issues. Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 (edited) 10 hours ago, Russell griffiths said: oh God, don’t use a flexi. 10 hours ago, PeterW said: Step away from the flexi.... turn the shower waste to point at the drain, pair of 45 bends to drop the level and straight into a strap boss ... Ok noted, but why no flexi if it's just for shower water? So I am pretty sure it's much easier for me to drop straight downwards through the fireboard, so I don't go through any joists. I had thought flexi so I didn't need to worry about the angle so much when dropping the tray onto the mortar bed I have to lay. The waste comes with this attachment (see pic). Do I point that downwards, cut a hole where it points, attach 40mm waste pipe to poke through whilst dropping the tray... then attach elbows on the other side? Feeling confused about how to make it work... ALSO as an aside, I am laying shower tray that needs a mortar bed, onto caberdeck. Should I tank it first? 1 hour ago, Tennentslager said: If your short of space one of these might help. Thanks will save this for later! Edited August 20, 2019 by Roz Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 1 hour ago, Tennentslager said: Do you have room to fit a couple of these on top of your waste pipe? Sorry didn't see this, would that be to bring the waste pipe towards where the toilet would be? Link to comment Share on other sites More sharing options...
PeterW Posted August 20, 2019 Share Posted August 20, 2019 19 minutes ago, Roz said: Ok noted, but why no flexi if it's just for shower water? They are ribbed inside and collect soap and scum, hair etc... Hot water makes them flexible and they sag, and then collect more crud ... and eventually they block and you can’t poke anytinf down them as they puncture easily ... other than that, they are great !! ? Looking at that waste you need to set the waste pipes correctly then unscrew the top, drop the tray over the top and do it up from above. Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 5 minutes ago, PeterW said: Looking at that waste you need to set the waste pipes correctly then unscrew the top, drop the tray over the top and do it up from above. Hmm but then I can't see how I would get the soil trap in the right position and correct height if I do it before laying the mortar etc as I don't know what height the mortar will end up in order to level? Also do I need a vent pipe for the soil pipe??? Link to comment Share on other sites More sharing options...
PeterW Posted August 20, 2019 Share Posted August 20, 2019 As long as there is a vent somewhere else on the system then no, but an anti-syphon trap on the sink is always a good move. The cement - or cement based tile adhesive - is only 5-8mm thick so the flex in the joints should accommodate that. Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 6 minutes ago, PeterW said: As long as there is a vent somewhere else on the system then no, but an anti-syphon trap on the sink is always a good move. There'll be a vent at the main house, but the two soil pipes don't connect until they basically reach the septic tank? Link to comment Share on other sites More sharing options...
PeterW Posted August 20, 2019 Share Posted August 20, 2019 Think about adding a low level vent near the tank instead - think @JSHarris stuck his in a flower bed ..! Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 15 minutes ago, PeterW said: Think about adding a low level vent near the tank instead - think @JSHarris stuck his in a flower bed ..! Thanks Peter. Do air admittance valves replace vents? What are your thoughts on whether I should tank the caberdeck before laying the mortar? Thanks Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 (edited) OK I'm getting mighty confused. If I use e.g one of these to connect the toilet to the soil pipe, and the sink waste to the same... And then underneath the floor (floating on jackpads) I connect the shower waste to the soil pipe using one of these... is there a specific distance these have to be away from each other? Should I, instead of using one of the above, cut away some of the soil pipe and replace with one of these so I can then have a vent pipe coming out? But the vent pipe would come out below the toilet pan connection(the pan would connect into the top and the vent to the side..), obviously end above it... but would that be OK? And instead of a full vent pipe could I just use an external air admittance valve instead on the top? Edited August 20, 2019 by Roz Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 Also, can vent pipes have bends, as in, that needed to get out from underneath the floor. Link to comment Share on other sites More sharing options...
PeterW Posted August 20, 2019 Share Posted August 20, 2019 Why are you venting it ..?? A plan may help here as I’m lost as to where everything goes ... Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 24 minutes ago, PeterW said: Why are you venting it ..?? A plan may help here as I’m lost as to where everything goes ... I just don't understand when I have to ? Hopefully the attached helps - showing the first floor of the house, and the workshop / studio is just one floor.. Was planning to vent the soil pipe at the top of the house but hadnt thought about it for the studio. Drain layout.pdf Link to comment Share on other sites More sharing options...
PeterW Posted August 20, 2019 Share Posted August 20, 2019 Ok if it was me I would put a stub vent behind the studio and then not worry about the house, just use anti syphon traps on the sinks. How much room is there under the floor to work ..? Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 (edited) 9 minutes ago, PeterW said: Ok if it was me I would put a stub vent behind the studio and then not worry about the house, just use anti syphon traps on the sinks. How much room is there under the floor to work ..? Do stub vents come out the same as normal vents I.e. where on the waste stack does it need to go? There's about 15cm under the floor but can probably scoop a bit of earth back out around the soil pipe? Edited August 20, 2019 by Roz Link to comment Share on other sites More sharing options...
PeterW Posted August 20, 2019 Share Posted August 20, 2019 Stub vent only has to be higher than the water level in the highest trap, so about 1200mm assuming there is no window in that back wall..? Take the tee you linked and drill out one of the bosses and insert a 40mm rubber insert. Then run the shower into that. WC goes into the top of the stack - not keen on those elbows with a waste Access but if it’s not a regularly used bathroom then it’s ok. The other 110mm branch goes out the back wall, 90 degree elbow and up the wall, ending with a mushroom cap. 1 Link to comment Share on other sites More sharing options...
Roz Posted August 20, 2019 Author Share Posted August 20, 2019 35 minutes ago, PeterW said: Stub vent only has to be higher than the water level in the highest trap, so about 1200mm assuming there is no window in that back wall..? Take the tee you linked and drill out one of the bosses and insert a 40mm rubber insert. Then run the shower into that. WC goes into the top of the stack - not keen on those elbows with a waste Access but if it’s not a regularly used bathroom then it’s ok. The other 110mm branch goes out the back wall, 90 degree elbow and up the wall, ending with a mushroom cap. OK great thanks so much. So it's OK for the vent attachment to be 'below' the toilet pipe inlet? I'll do that. No window on that back wall no, so thats fine. Link to comment Share on other sites More sharing options...
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