Waste Pipe Size 32mm 40mm

[User]

Hiya, for some reason the waste pipe going from my bathroom to the outside soil pipe is 32mm instead of 40mm

The pipe from the bath is 40mm then is converted to 32mm

This seems totally wrong to me

Unfortunately it is almost impossible to change because a massive extension roof covers the outside pipe totally

I am moving the sink a few metres further away making it 4m away from where it is teed into the bath waste pipe

I will be using a an anti-vac trap on the basin due to the length

I know I should use 50mm usually but since there is 2m of 32mm pipe going to the soil pipe which I can't change should I just use 32mm all the way now

I am worried that if I use 4m of 50mm pipe then 32mm to the soil it may create problems

Please somebody help this is a predicament indeed

 

[seco services]

i take it the extension is pitched roof and the only access is from the tiles or the ceiling ?

 

[Richard C]

The pipe from the bath is 40mm then is converted to 32mm
This seems totally wrong to me

It is totally wrong & does not comply with Building Regulations.

Unfortunately it is almost impossible to change because a massive extension roof covers the outside pipe totally

Very few things are impossible There is usually a way around it although it may not be easy & you may not like it. As it is, it will never comply with Building Regulations & will be viewed as unauthorised building works if picked up under a potential house buyers survey. It also makes me wonder if the work was ever inspected & passed in the first place!

I am moving the sink a few metres further away making it 4m away from where it is teed into the bath waste pipe
I will be using a an anti-vac trap on the basin due to the length
I know I should use 50mm usually but since there is 2m of 32mm pipe going to the soil pipe which I can't change should I just use 32mm all the way now
I am worried that if I use 4m of 50mm pipe then 32mm to the soil it may create problems

You should never step down in waste size; it’s just asking for trouble & is why it’s not permitted under Building Regs. You need to find a way of installing the correct size waste run which is 40mm minimum & for tee’d connections should really be 50mm; you will almost certainly need anti vac traps or other means of ventilation to comply with the maximum permitted length of unvented branch waste runs & to prevent siphoning the traps.

Do you have a w/c in the same room?

 

[dextrous]

What is the distance that the pipe has to run through the extention roof?

 

[User]

Mr Services yes that's correct it is a pitched roof

Mr C yeah it probaly wasn't passed, there is a WC in the room inbetween the basin and bath if it had a right angled outlet I could have used one of those WC pipes with extra outlet for basin waste pipe but they only come in right angled connectors unfortunately

Mr dextrous the distance of outside pipe is about 2m

 

[Richard C]

So does the w/c outlet get in to the soild stack; does it go straight out through the wall?

A photo or sketch may be usefull.

 

[User]

Yeh Mr C it does it goes straight through the wall then turns horizontal a very short distance into the vertical soil pipe

 

[Richard C]

Can you not get a boss strap (top entry) onto the length of 110mm pipe before it dives out through the wall?
Or, presumably, you cant take the waste pipe out through the same wall & into the stack outside?

 

[User]

It's a very good idea Mr C but the length of 110 pipe is simply too small the hole would probaly be half covered by the rubber of the WC connector and would probaly crack the pipe at such a small distance

Again if that roof weren't in the way I could drill thorugh no prob

I was hoping that if I put anti-vac trap on the sink and anti-vac in-line on bath trap (can't find an anti-vac shallow bath trap) that would hopefully prevent most of the siphonage problems with using 32mm pipe everywhere

 

[Legion]

If it`s that difficult just upsize all your new pipework to 40mm apart from wash basin 32mm and reduce to 32mm to connect to existing waste. It`s not the end of the world and I`m sure no inspector is gonna come around and start ripping off your bath panel/extension roof to check the 8mm difference. It`s not ideal but your house isn`t going to fall down because of it. Let`s keep it real folks!

 

[dextrous]

If the run of 32mm pipe through the new roof void is straight, you could chop out the surrounding mortar from the outside and enlarge the point of entry inside. Then, removing the elbow or tee on the outside of the building, use the 32mm pipe to run as a guide for a new section of 50mm (put the 50mm concentric to the 32mm so it runs along the same route), and withdraw the 32mm. Thus you have replaced the 32mm with 50mm and your problem is solved.

If there is an elbow within the roof void, then you may be able remove a couple of bricks to create an opening big enough to get your hand in and replace the section this way. Without seeing it, it's impossible to be certain.

 

[Richard C]

If it`s that difficult just upsize all your new pipework to 40mm apart from wash basin 32mm and reduce to 32mm to connect to existing waste. It`s not the end of the world and I`m sure no inspector is gonna come around and start ripping off your bath panel/extension roof to check the 8mm difference. It`s not ideal but your house isn`t going to fall down because of it. Let`s keep it real folks!

There’s always one isn’t there The important thing is to give correct & good advice; personally, I don’t give a **** if the OP doesn’t take it, that’s’ his prerogative as long as he knows the situation. Restricting a waste run won’t comply & is “cowboy” advice; even if he never gets found out it will eventually block & if the unvented runs are too long, will be plagued by smells.

 

[Legion]

Other solution is to drop main waste through floor into room below if there is some waste arrangement there and box it in or drop it down and out through wall, run most of it externally if possible.

 

[Legion]

The important thing is to give correct & good advice; personally, I don’t give a s**t if the OP doesn’t take it,

OI. OI, what you getting excited for, mind yer language.

Restricting a waste run won’t comply

How many don`t and how many customers give a monkeys about compliance?

& is “cowboy” advice;

It`s realistic advice, get your head out your ass live in a plumbers/real world and stop quoting Regs. We can all do it.

even if he never gets found out it will eventually block & if the unvented runs are too long, will be plagued by smells.

Not with anti vac traps, if it`s impossible to replace without the advice I have given it`s the only way. Why will it eventually block? where did you read that?

Theoretical advice is good advice, not always the best. if you went into every home telling the customer how this didn`t comply and that didn`t comply you would get laughed out of the house. Stop being so self righteous, so you can read a plumbing book, big deal.

 

[Richard C]

OI. OI, what you getting excited for, mind yer language.

I’m not getting excited; language, did I use bad language – ohh maybe it was COWBOY you didn’t like.

How many don`t and how many customers give a monkeys about compliance?

Er so the fact they don’t know what's right & isn't & havn't a clue they are being given cowboy advice makes it right then; ohh I can see where I've got it wrong now

It`s realistic advice, get your head out your ass live in a plumbers/real world and stop quoting Regs. We can all do it.

Mmm head up my arse ----- no, can’t see any sh ite in here; "Plumbers World" now let me see, where is that then, on the local industrial estate; oh no that’s "Plumbworld, do they give GOOD advice then.

Not with anti vac traps, if it`s impossible to replace without the advice I have given it`s the only way. Why will it eventually block? where did you read that?

Simple physics my friend; 40mm to 32mm = restriction; surely even a cowbow must be able to work that one out; but I forgot, you don’t give a rats ass!

Theoretical advice is good advice, not always the best. if you went into every home telling the customer how this didn`t comply and that didn`t comply you would get laughed out of the house.

The customer generally doesn’t have a clue & is relying on you the "tradesman" to do a decent job that complies with relevant regulations. That may involve one or two dodges but, in my book, does not involve a complete bodge. I don't like over regulation & some of it is really stupid but, like it or lump it, that’s what the customer has every right to expect. So if you told your customer “I can either do it properly which means you shouldnlt have any problems at all or I bodge it to save some time & a few quid (or because I don't know what I'm doing or am simply a lazy bstard) but you probably will have problems” what do you think he would say? I would rather hope it would be you that would get laughed out of the house but with some customers, you never know.

Stop being so self righteous, so you can read a plumbing book, big deal.

Not being self righteous at all just trying to give correct & good advice; as I said, I don’t give a ****, if the advice is followed or not but it is the correct advice which is born out by simple physics. Plumbing books, now lets see; ahh yes, I did read a few once I think when I was studying but I don’t actually have any now.