Moving bathroom - New en-suite - Wastes

[Joe4542]

Hi guys, hope someone (or all!) can help!

I've been asked by a mate to give him a hand moving his bathroomand making a small ensuite. I dont normally get involved with the waste side of things so we wanted to run the general ideas past you for vetting...

Below are a couple of pics to give you an idea of the situation.
First is the current view of outside Soil.
View media item 12001
This one shows the proposed layout from above (on left) and the view as it would be from outside (on right).
View media item 11999Hope the second is clear?
basically the soil pipe runs from the toilet out to join existing stack below current soil pipe from another wc, joined onto this via a boss section would be a 50mm/2" pipe which drains the bath and 2 back to back basins either side of a stud wall. Further down the soil branch will be a 40mm/1-1/2" pipe via a strap on boss, which drains the shower tray.

All the pipe runs will be within those given in Approved Doc H1 (drainage), which would suggest that we don't need any further branch ventilation (to avoid any trap siphonage), the main stack is vented thru the eaves above the roof level.

Does anyone think we will still need to vent the main soil branch outside (shown on diagram) with an AAV/durgo (dont want to go with normal open vent since would have to take pipe up roof (has loft conversion which we would have to go above).

Any and all comments/questions welcomed!!
cheers

 

[seco services]

i take it your moving the bathroom to another area of the house ?

 

[Joe4542]

yes he is, the current bathroom is on the right of the top photo, the soil pipe coming into the picture from right is the bathroom wc with smaller pipe below it being the other wastes.

He's built a stud wall in one of the bedrooms to divide it off
(for a ensuite) then knocked hole thru for new doorway from his main bedroom.

So basically - moved 1 room along, around the corner .

 

[seco services]

you know this is a bco issue ?

 

[Joe4542]

Thought it might be - when I told my friend, he said thats OK, since apparently he knows someone in council - either way he didn't seem to bothered.

I got the impression whether it was 'allowed' or not, he'd be going ahead with it anyway
...so may as well give him a hand

 

[Redhotferrari]

Cant see a reason why its 'not allowed' but you MUST get BCO first, charges depend on the actual cost of work involved.

Dont understand why people try and dodge this, its one form, a bit of money, couple of inspections, sign off, job done, everybody happy!

You could just do it, but will be almost impossible to sell the house in the future.

Good luck

 

[Richard C]

Cant see a reason why its 'not allowed' but you MUST get BCO first, charges depend on the actual cost of work involved.

Dont understand why people try and dodge this, its one form, a bit of money, couple of inspections, sign off, job done, everybody happy!

You could just do it, but will be almost impossible to sell the house in the future.

Good luck

Very sound advice. I don't understand this sort of mentality either; the relevant BR's cover more than just drainage/waste connections & the fee is hardly a significant factor as a proportion of the overall cost. Neither do I understand how “knowing someone in the council” will magically make it OK; perhaps it’s the gardener

 

[Joe4542]

Ok thanks for all the comments regarding BCO - i shall push this fact on with my friend.

Other than the above any comments as to proposed design/layout.
AAV likely required?
OK with bath an sinks joined - keep shower tray on separate waste?

Ta

 

[Richard C]

When forming a new room (the en-suite) containing a w/c, any stud partitions between it & another habitable room must be sound insulated to comply with current Building Regs.

Overall it’s less than ideal; separate direct stack connections for each service are always recommended & preferred. Failing that, keep all the connections on the top of the 110mm branch & separate if at all possible. Unless you use an ant siphon trap, the bath will continually draw the sink trap when emptied & it’s possibly the 2 sink traps will draw each other. Why are you running the wastes through the external wall, you give no dimensions but there are maximum, unvented lengths for waste runs under Part H; is there a joist problem? I assume you can get the required falls under the floorboards!

If possible I would try & connect into the 110mm branch with the shortest waste runs possible, even if it means extending the branch & fit the AAAV internally at the toilet end to provide the necessary ventilation; to be less obtrusive, is it not possible to vent out through the wall adjacent to the w/c? Fitting the AAAV externally will require the correct type, you cannot fit an ordinary AAAV externally. If it’s the only open vent, you must also leave the existing stack open to provide positive ventilation on the system. You will also need to provide access to all sections of the 110mm branch from one end or the other to the existing stack.

 

[Joe4542]

Hi richard, thanks for replying.

The stud wall is between what will be a bathroom, and a small ensuite for the main bedroom - think he is planning on insulating anyway.

Basic room layout
View media item 12046
Separate connections to stack would be difficult at best - not to mention ugly with all the pipes... most of the wastes could be brought out from their origins to tee into the new 4" soil branch - as per the diagram i'd posted at top, all the connections would go into the top of soil pipe using either boss sections or strap-ons. Suppose could run the bath separate from sinks thru same joist span - but then they would exit the wall very close to each other - suppose i could get a boss section with 2 entries on one side?

I thought the traps would be ok since following the tables in Doc H1, i'm keeping the lengths and falls of pipe runs within allowed limits which are supposed to then stop syphonage? Only iffy bit would be ~200mm drop as they come out of the wall into top of 4" branch (to allow for angle on branch) obviously a vertical drop is more than 1/11 max stated in tables - but since it was a short section maybe ok?

The pipes were all going underfloor to ext wall since the toilet is only one which would have access to the 4" soil as that is in one span, the other wastes would have to have bl**dy great nothches cut in joists accross room - didn't like that idea...
Std 8/9" joists so can get falls req'd - even on 4".

Don't think connecting wastes to soil internally would be possible - but could poss put AAV internal by toilet, thought if neccesary AAV could be fitted outside (know it'd need to be external one).

The main stack will still have its open vent left alone.

Also thought, he wants another WC put back to back with current one on bottom/left of above pic. Should be able to run new one thru wall into a tee, into current soil branch? Regs H1 say you can put up to 8 toilets on one run?

 

[Richard C]

The stud wall is between what will be a bathroom, and a small ensuite for the main bedroom - think he is planning on insulating anyway.

Bathrooms are not classed as habitable rooms so your OK there; also you don’t have to insulate any walls in the bedroom the en-suite serves; it’s perfectly OK to hear your partners farts but not those from next door!

Separate connections to stack would be difficult at best - not to mention ugly with all the pipes... most of the wastes could be brought out from their origins to tee into the new 4" soil branch - as per the diagram i'd posted at top, all the connections would go into the top of soil pipe using either boss sections or strap-ons. Suppose could run the bath separate from sinks thru same joist span - but then they would exit the wall very close to each other - suppose i could get a boss section with 2 entries on one side?

I thought the traps would be ok since following the tables in Doc H1, i'm keeping the lengths and falls of pipe runs within allowed limits which are supposed to then stop syphonage?

The lengths given are for unvented SEPARATE branches into a vertical stack, when you start combining waste runs, you can get problems. It’s all to do with how the water travels down the pipe taking the air with it until you get to a point where negative pressure will suck the water either out of the trap it’s just come from or, in the case of, say a sink teed into a larger shower run, the shower can pull the sink traps & the volume of water from a w/c running down an unvented soil branch could possible suck the water from all the traps behind it; if your really that interested in the theory, Google can produce some nice bedtime reading It’s not a difficult problem to overcome though with a strategically placed AAAV, it’s a question of getting the best run to start off with.

Only iffy bit would be ~200mm drop as they come out of the wall into top of 4" branch (to allow for angle on branch) obviously a vertical drop is more than 1/11 max stated in tables - but since it was a short section maybe ok?

Cant’ see a problem with that if your wasting into a vented branch.

The pipes were all going underfloor to ext wall since the toilet is only one which would have access to the 4" soil as that is in one span, the other wastes would have to have bl**dy great nothches cut in joists accross room - didn't like that idea...
Std 8/9" joists so can get falls req'd - even on 4".

Just checking so as I suspected.

Don't think connecting wastes to soil internally would be possible - but could poss put AAV internal by toilet, thought if neccesary AAV could be fitted outside (know it'd need to be external one).

The best solution would be a new soil stack & foul drain connection on the outside of the wall next to the new loo; obviously a lot more work & I can see why that may not be 1st choice. Failing that (& looking at it from here) I would probably still shove the 110mm branch out through the wall next to the new loo & fit either an external open vent if you can or an AAAV on the outside wall; that will vent the whole soil branch & you won’t have any problems with siphoning either the w/c or other waste connections, the only thing you have to take care of then is the bath siphoning the 2 sinks & if you can get a direct connection from the bath to the soil branch, no problem.

Have a look at this design guide; it’s really useful & not only covers BR requirements but gives some very useful solutions;

http://www.hunterplastics.co.uk/download/27/Complete brochure.pdf

 

[Joe4542]

Ok thanks for taking the time to respond richard.

Looks like I'll be telling him we need to pass the soil back out thru the wall behind WC, then vent it up the wall some. Only prob is, was hoping to keep pipe in the floor, but gonna have to bring it above floor to go out wall, else would need to chop out half the joist resting against wall... no good

Thinking about it - he was talking about putting window in this wall by toilet (is in 6' space between houses), there are no windows in next doors wall either. I know if I wanted to open vent it, it would need to go above the said window by 900mm cos within 3m, but would I still be ok to stop there even tho there is a loft room above - No further openings within 3m?
If not I could just go for an External AAV and be done with it!

As for the wastes - think I'll suggest we just err on the safe side and do 3 runs, 1 for bath, 1 for shower, and 1 for basins (fitted with anti-syphon traps).

What would you say is better for the three connections into the top of the 4" soil? 3 - Strap bosses, 3 - short boss sections, 3 - normal boss sections OR pick an mix

Cheers again!
Joe

 

[Richard C]

Thinking about it - he was talking about putting window in this wall by toilet (is in 6' space between houses), there are no windows in next doors wall either. I know if I wanted to open vent it, it would need to go above the said window by 900mm cos within 3m, but would I still be ok to stop there even tho there is a loft room above - No further openings within 3m?

As long as you comply with the 900mm above within 3m openings rule it’s OK.

If not I could just go for an External AAV and be done with it!

You could do but I would go for an open vent if possible.

What would you say is better for the three connections into the top of the 4" soil? 3 - Strap bosses, 3 - short boss sections, 3 - normal boss sections OR pick an mix

Up to you really, whatever is most convenient & looks the best.