110mm soil pipe locations in insulated raft foundation + Shower help

[HanleeHouse]

Hi all, I'm about to start work on drainage and insulated raft foundation in 2 weeks time. 

 

Please could you help with the drainage through the raft foundation? 

 

- Is all of the drainage that comes up through the raft 110mm? How far above FFL should they pop up? 

- Long radius bends with foot at each location? 

- There are 2 SVP's serving the FF. One serving a Master Bedroom Ensuite and the other Serving 2 en-suites. Do these need to extract through the roof or AAV in the loft? 
- Downstairs WC, does that need its own AAV? Does this need 2 outlets, one for sink and one for toilet? 

- Toilet in downstairs en-suite, can that connect to the same run as SVP?

- How would you deal with the shower tray in the downstairs en-suite? 

 

Any other general advice would be much appreciated too. Cheers!

 

 

- 

[Gone West]

@HanleeHouse I had an insulated raft foundation and all the 110mm soil pipes had long radius bends with feet and came up through the insulation and were around 0.5m above concrete level. That is except for the downstairs wet room shower waste where the 110mm pipe finished around 150mm below concrete level and was surrounded by a large block of polystyrene which finished above the concrete level. This enabled me to remove the polystyrene after the concrete had set and adjust the pipe length for the sunken shower waste. All the pipes had AAVs which were hidden behind false walls as the upstairs rooms had vaulted ceilings. We had our own STP and didn't have a vent on the house but on the STP.

 

 

 

Edited April 7 by Gone West

[JohnMo]

5 hours ago, HanleeHouse said:

How far above FFL should they pop up? 

Our pipes were below everything (at hardcore level, so about 450mm below FFL.

 

5 hours ago, HanleeHouse said:

How would you deal with the shower tray in the downstairs en-suite? 

We took 110mm pipe to the shower tray and then stopped screed / concrete with additional insulation, to act a mould. Once I was ready the insulation was removed, to leave a void to work with. The drainage fully completed for the shower tray, I back filled the space with concrete, then did flush fit shower tray.

[HanleeHouse]

49 minutes ago, JohnMo said:

Our pipes were below everything (at hardcore level, so about 450mm below FFL.

 

We took 110mm pipe to the shower tray and then stopped screed / concrete with additional insulation, to act a mould. Once I was ready the insulation was removed, to leave a void to work with. The drainage fully completed for the shower tray, I back filled the space with concrete, then did flush fit shower tray.

Thanks for that, I will look at doing the same.  

[Nickfromwales]

7 hours ago, HanleeHouse said:

Downstairs WC, does that need its own AAV? Does this need 2 outlets, one for sink and one for toilet? 

- Toilet in downstairs en-suite, can that connect to the same run as SVP?

If the invert (drop from vertical to horizontal) is less than 1300mm then no AAV required, push back if BCO insists!

 

SVP can take these without issue, providing the lot stays at 110mm (smaller pipe can be used if it's just a vent). Where solids are introduced there are rules to follow regarding the runs being pretty much straight to the inspection chambers, without any changes in direction. If you have to use a bend then rodding access should be provided where the soil stack appears above concrete / FFL. 

[HanleeHouse]

16 minutes ago, Nickfromwales said:

If the invert (drop from vertical to horizontal) is less than 1300mm then no AAV required, push back if BCO insists!

 

SVP can take these without issue, providing the lot stays at 110mm (smaller pipe can be used if it's just a vent). Where solids are introduced there are rules to follow regarding the runs being pretty much straight to the inspection chambers, without any changes in direction. If you have to use a bend then rodding access should be provided where the soil stack appears above concrete / FFL. 

Thanks @Nickfromwales Does the rest of the plan seem to make sense? Would you make any changes?

[Nickfromwales]

8 hours ago, HanleeHouse said:

There are 2 SVP's serving the FF. One serving a Master Bedroom Ensuite and the other Serving 2 en-suites. Do these need to extract through the roof or AAV in the loft? 

You can have the vent as a remote SVP stack, behind an outbuilding for eg, if you prefer to not penetrate the roof, but at the worst you only need 1x SVP and then the other can be an AAV.

 

8 hours ago, HanleeHouse said:

How would you deal with the shower tray in the downstairs en-suite? 

That depends on what it is going to be; tray / flush to floor tiled over wetroom former / other. Info please!!  Maybe show us pics of what takes your fancy and we can work from there 👍

[HanleeHouse]

12 hours ago, Nickfromwales said:

You can have the vent as a remote SVP stack, behind an outbuilding for eg, if you prefer to not penetrate the roof, but at the worst you only need 1x SVP and then the other can be an AAV.

 

That depends on what it is going to be; tray / flush to floor tiled over wetroom former / other. Info please!!  Maybe show us pics of what takes your fancy and we can work from there 👍

Cheers @Nickfromwales I've just measured out the en-suite and we're looking at having a 1400x800mm shower tray. I'm looking at something like this - Not looking to go flush, but just low profile. 

https://www.plumbworld.co.uk/hydrolux-low-profile-rectangular-shower-tray-1400-x-800mm-with-waste-19421-1270350

 

Thanks again

 

[HanleeHouse]

Hi All, 

 

I drew myself a plan and laid the drainage. Ready to finish levelling and just need to add the water & electric ducts. 

 

 

When I get to the stage of laying the DPM over the EPS, what's the best practice for laying the DPM around the penetrations? Tape? Liquid DPM? Should I be using foam filler around any gaps too? Is there any recommended EPS friendly foam filler? 

 

Appreciate your help guys. Learning on the go! 

 

Cheers 

[JohnMo]

14 minutes ago, HanleeHouse said:

EPS friendly foam filler

Just about any expanding foam filler is ok with EPS. Dampen the edges of the EPS just prior to the expanding foam. It helps with expansion and curing.

[Oz07]

@Gone West @JohnMo How were you guys connecting the eps to the soil pipe to form a tray for the shower? What kept the eps at the right level and stopped the concrete floating it up? I did a similar thing with board of ply or mdf years ago just to give me a 20mm recess in the slab and it was a bit of a pain. Presumably you were still letting concrete flow under the eps former and not shuttering off the whole shower area?

 

In most recent build I just positioned pipe perfectly for shower tray and had low profile tray on top of slab with straight waste and like a pan connector type rubber around it to connect to 110mm soil.

[JohnMo]

7 minutes ago, Oz07 said:

What kept the eps at the right level and stopped the concrete floating it up?

I PIR in our foundation, but I used long screws about 150mm long. Just pushed through and when it came to break it out just smashed it all out.

 

9 minutes ago, Oz07 said:

Presumably you were still letting concrete flow under the eps former and not shuttering off the whole shower area?

Our concrete above the floor insulation was 100mm so used a 100mm PIR former.

 

Once I had sorted the drains etc, just back filled with concrete by hand.

[Oz07]

I see thanks. I was just forming a 20mm dip in the slab for a wet room style shower and it was more pain than I anticipated

[Gone West]

12 hours ago, Oz07 said:

How were you guys connecting the eps to the soil pipe to form a tray for the shower?

In my case the EPS wasn't connected to the soil pipe and it was a fully tiled floor wet room, without a shower tray. The block of EPS was on top of the vertical end of the soil pipe in order to stop the concrete from being too close to the soil pipe to allow me to work on the soil pipe to get the correct level for the shower drain.

[Nickfromwales]

Just cut a dozen or more (x) depth PIR chairs to sit on the DPM or rebar and then place a piece of 100mm PIR or EPS on top of them the size of the area plus maybe 50mm extra in each direction. If over rebar, fit concrete mars bars directly under where your PIR chairs will go to stop the deflection when you add ballast. 

 

Wrap a bin liner around the soil pipe, then foam around that as much as you need to. That needs to be done so as to prevent concrete getting to or into the pipe, so do that well! A coupler and blanking plug is the best option, but you’ll need to get the pipe cut quite low for that. Easily doable with a multi-tool and some patience.

 

Place a load of concrete blocks or sand bags / other ballast on top of the 100mm sheet and get on with the pour; this will give a ‘perfect’ result. 

 

Hack it all out 24hrs after the pour when the concrete is still ‘green’ and that’ll allow you to easily undertake any further chasing out necessary to fit the tray / former / waste & pipework etc.

 

There are loads of ways to over-engineer this btw, and the last load of these I’ve done have been ludicrously complex and time-consuming…..(not). Just get a load of sharp sand and shovel it in to blind off the area and shovel / Henry hoover it all back out the next day or so. Takes appx 10 mins to shovel in, 20 mins to remove, perfect results every damn time. . Bench the sand like making a sandcastle and go 75mm bigger x&y, have it around 50mm higher than TOC, and tell the concrete guys to go easy there so as to not disturb it. I ask them to stop short as it doesn’t matter, and later I back fill with cementitious leveller or a builders screed with fibres, depending on rebar or not.

 

16 hours ago, Oz07 said:

I see thanks. I was just forming a 20mm dip in the slab for a wet room style shower and it was more pain than I anticipated

 

“KISS”, folks. Works a charm. Tools required = 1x sand and 1x shovel. 👌. 

[saveasteading]

1 hour ago, Nickfromwales said:

coupler and blanking plug is the best option

Or a metre or so vertical pipe with bag over it  It's It's very visible so less likely to be  bumped

 

1 hour ago, Nickfromwales said:

Henry hoover it all back out the next day

That's why I read this stuff. I'd never seen or  thought of that.

A wet and dry, bagless machine is cheap too.

[Nickfromwales]

34 minutes ago, saveasteading said:

Or a metre or so vertical pipe with bag over it  It's It's very visible so less likely to be  bumped

 

That's why I read this stuff. I'd never seen or  thought of that.

A wet and dry, bagless machine is cheap too.

Either option but if the coupler is on then another damage mitigation policy imo.

 

The sand shutter option is ridiculously cheap, quick, effective and simple. Couple of pays with the back of the shovel to compact as you go, and the concrete just bounces back away from it.

 

Henry has been a soldier over the years, no task has beaten him yet. Same one for 20 years, just has had 40 new hoses and 6 new main units lol. 

[Oz07]

My effort 10+ years ago with the wet room style vertical trap gaffer taped. Had a board of MDF set 20mm lower from memory 

Edited April 23 by Oz07