Question about pipe work drainage

[HawkEye244]

This is simple to someone that knows I would have thought.

Basically I'm struggling to put these pipes together, they are going to be boxed in afterwards.

Problem is I don't know what to do here.

As the pictures show the stack terminates inside the room with an aav attached to it.

I've been told the aav needs to terminate above the highest drainage point which will be a sink going in on the right side of the rad in the picture.

I'm looking at building reg part H page 10 which says that to prevent cross flow contamination you need to offset the pipes into the stack, but I don't understand what it says. It talks about manifolds at one point and then 200mm another, and then 50mm min. I need to get this right first time.

Oh yeah in the corner a toilet is going to the right of the window (in the picture)

Please help someone, many thanks

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[HawkEye244]

I also have a question about solvent weld versus compression joints, is there a particular circumstance one would be more beneficial over the other or is it completely down to preference?

I plan to use compression joints because the pipes can be dismantled, but at the moment unsure

 

[longdogs]

Solvent weld = unlikely to leak

Compression = Possible leak but handy if you need to remove for any reason.

Compression for connecting plastic waste pipe to copper waste or if sizes vary

 

[longdogs]

If pipes are going under the floorboards? then definitely use solvent weld

 

[HawkEye244]

All pipes are running above the floor because I didn't want to have to drill out 40mm through joist work. As in the picture the shower tray is on a raised platform to allow for this.

The most important question is how to connect the toilet waste and shower/basin waste to the stack?

 

[Newboy]

Where is the waste for the pan going and where is the stack & AAV?

AAV needs to be 300mm higher than highest overspill level (lip of basin)

This is a waste water manifold

http://www.screwfix.com/p/waste-manifold-grey-sp588/22367

Crossflow prevention is covered on page 8 of this document

http://www.planningportal.gov.uk/uploads/br/BR_PDF_AD_H_2010.pdf


Seconded - don't use compression or pushfit under floor or concealed inside boxing

 

[HawkEye244]

Hi,

The second picture shows the waste pipe sticking up through the floor, it's a little difficult to see in the picture but it is there, some bits of timber are sitting against it.

The aav is seated inside the stack, but I can extend the height if necessary to allow for more length about the basin lip.

Perhaps I'm not being clear with the main question.

The question is how do I connect the toilet waste to the stack?

How do I connect the 40mm shower/basin waste to the stack?

I don't understand the regulations

I'm clear on the use of fittings and will use solvent weld as suggested.

The waste manifold looks useful but in this room there is one 40mm waste pipe and one 110mm toilet waste, so is that necessary?

 

[Newboy]

Sorry - didn't spot the soil pipe in your photo!

You need to cut the stack and fit something like this (not sure where your final pan location will be)

http://www.screwfix.com/p/92-5-87-5-branch-grey-sp190/12454
into
http://www.screwfix.com/p/pipe-coupler-double-socket-grey-sp105/14551

Then extend the stack up and fit the AAV to it as previous post.

You 40mm waste can then be connected using a spigot into one of the side connections on the T (assuming you have enough fall from the appliance)

Edit - Is this an existing stack and did it already have an AAV?

 

[HawkEye244]

Sorry - didn't spot the soil pipe in your photo!

You need to cut the stack and fit something like this (not sure where your final pan location will be)

http://www.screwfix.com/p/92-5-87-5-branch-grey-sp190/12454
into
http://www.screwfix.com/p/pipe-coupler-double-socket-grey-sp105/14551

Then extend the stack up and fit the AAV to it as previous post.

You 40mm waste can then be connected using a spigot into one of the side connections on the T (assuming you have enough fall from the appliance)

Edit - Is this an existing stack and did it already have an AAV?

Thanks for the confirmation, I fitted the stack all the way through the building (spans 3 floors) as conservation area status meant I couldn't fit a new stack to the outside of the house.

At the time I hadn't researched how the toilet waste actually connects to the stack, despite seeing these branch fittings being used everywhere haha. I was hoping I could drill a hole for the toilet waste and fit a collar boss to avoid cutting the main stack but it's no problem really and more peace of mind fitting a branch.

The toilet is going to the right of where the stack is, in that corner, so if I attach the toilet to the right side of the stack and then attach the shower/basin waste to the other am I meeting regulations?

Am I right in thinking that cross-flow is a problem only when two pipes are connected directly opposing each other? This branch connection you mention has bosses directly side by side the toilet waste but not directly opposite so must be ok??

Also the branch connection says it has options of 32mm or 40mm, will either hole be able to be used for the 40mm as I only have one to choose from as the other will be facing completely the wrong way and against a wall?

Lastly it says on the description that silicone lubricant is fine for the joint. I'm assuming this stuff will be ok? http://www.wickes.co.uk/Wickes-Silicone-Lubricant-250ml/p/432013

 

[Newboy]

I'm not sure I understand your final position for the WC - 40mm waste at right angles is fine, but your description suggests the branch parallel to the wall behind the stack?

The branch will allow 32 & 40 mm into either side, you need to hole saw(just smaller than the moulded 'port') the branch in whichever side you wish and then fit the appropriate spigot (solvent weld the spigot and then solvent weld the waste pipe into it.

silicone lubricant is fine for the 110mm pipe (keep the bits you're going to solvent weld free of silicone). You need to taper/chamfer the cut end of the stack and make sure that it's de-burred otherwise you run the risk of damaging the seals (or pushing them out)

 

[HawkEye244]

I'm not sure I understand your final position for the WC - 40mm waste at right angles is fine, but your description suggests the branch parallel to the wall behind the stack?

The branch will allow 32 & 40 mm into either side, you need to hole saw(just smaller than the moulded 'port') the branch in whichever side you wish and then fit the appropriate spigot (solvent weld the spigot and then solvent weld the waste pipe into it.

silicone lubricant is fine for the 110mm pipe (keep the bits you're going to solvent weld free of silicone). You need to taper/chamfer the cut end of the stack and make sure that it's de-burred otherwise you run the risk of damaging the seals (or pushing them out)

Thanks very much.

What I meant to mean was the wastes at 45 degrees will mean the 40mm pipe stick out the front of the stack.. I guess this will mean I will need to extend the depth of the box to cover it up, I wanted to avoid this really but I guess it's the only option.

Just having a look at the different solvent weld brands now, does it make a difference if you use different brands or does all the pipework need to be the same brand?

 

[Newboy]

No need to stay with same brand - just pick a decent one!
Make sure that you use the correct solvent for the type of pipe you're using and keep joints clean/prep properly.

Before you use the solvent put the joints together dry and mark for angles and depths. That way when you put it all together you know that it fits properly.

Still a bit bemused about the final locations of pan & angles for branch etc

 

[HawkEye244]

No need to stay with same brand - just pick a decent one!
Make sure that you use the correct solvent for the type of pipe you're using and keep joints clean/prep properly.

Before you use the solvent put the joints together dry and mark for angles and depths. That way when you put it all together you know that it fits properly.

Still a bit bemused about the final locations of pan & angles for branch etc

What do you mean about the final location of pan and angle for branch?

I'm all ears if you can think of a better way to do this ?

 

[Newboy]

I'm trying to understand where the pan is going in relation to the stack (a quick sketch would help)

If you're planning to put the pan to the right of the stack (in your first photo) then the branch will need be turned parallel to the wall which means that your 40mm waste will need to make 5 turns to get to the stack.

The fall may well be an issue. It may be possible to run the 40mm waste below the bath and drop below floor directly in line with the stack which will reduce the number of bends, the need for boxing & may give the required fall.

Any help?

 

[HawkEye244]

I'm trying to understand where the pan is going in relation to the stack (a quick sketch would help)

If you're planning to put the pan to the right of the stack (in your first photo) then the branch will need be turned parallel to the wall which means that your 40mm waste will need to make 5 turns to get to the stack.

The fall may well be an issue. It may be possible to run the 40mm waste below the bath and drop below floor directly in line with the stack which will reduce the number of bends, the need for boxing & may give the required fall.

Any help?

Yes I see what you mean.

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What about the above pictures where the pan is 45 degrees to the wall?

This will need careful planning with the boxing in but it's the only way I can have the stack and the pan connect comfortably I think?

Here's a picture, if I have the toilet at 45 degrees to the wall will it look odd? Obviously will do my best to box in all the pipe work

With this scenario the shower will need to be raised about 400mm above floor level to get a comfortable fall, and to avoid notching out any joists. I'm happy with this as would need only one step up to the shower. What do you think?

Also just to say isn't it 4 bends for the 40mm to the stack? If there is enough fall will this be a problem? I just want to avoid drill through joist work and will be difficult now