Underground drainage advice please.

[mutley racers]

Hi all. I have not done any drainage as of yet but will be next week.

I am taking out a macerator and instead installing a soil stack and underground drainage to an existing man hole.

Q1) can I use a short radius (rest) bend at the foot of a stack? When looking online it does say that this is what they are for. But there are also long radius bends which you can use.

Q2) How far below ground does the drainage pipe have to be?

Q3) Can I use sand to lay the pipe on and then cover it with sand or should it be pea shingle? Maybe pea shingle will go a lot further.

Q4) I am hoping to pop through the side of the manhole close to 2/3s the way up and drop down and chase shoe into the benching. Does anyone know what mix this benching is? I know there is a name for this installation but I cannot think of it.

Cheers all

 

[SimonG]

I normally just ask building control what they want to see.

 

[mutley racers]

I was thinking of putting in an internal backdrop connection but from reading online it is frowned upon. Don't fancy digging down down down though

 

[SimonG]

Last one they just had me core through side of manhole, push pipe through and terminate with a 90° bend pointing down.

 

[Burger]

Have you tried downloading building regulations document H?

 

[mutley racers]

Have you tried downloading building regulations document H?

No, not yet. Will try now thanks.

 

[mutley racers]

Last one they just had me core through side of manhole, push pipe through and terminate with a 90° bend pointing down.

Oh really, now that would be nice but doubt that will be the case here. Will call them up today

 

[Ben-gee]

Are you looking to get it done to pass building control or are you looking for trouble free future? (ie is it your own place).
If the former, do whatever they let you get away with.
If the latter, dig down and do it properly. The “least work” robust way is to dig right down at manhole so as to enter horizontally at sewer pipe level. A couple of feet away from this you can then employ the ‘back drop’ method with no worries - better if you use a nice slow bend at the base of back drop and you also need to add rodding access to this (basically at top of back drop use a branch rather than bend, with rod point on vertical section).
I did this at home 7 years ago and no problem since (why did I write that down.....)

 

[mutley racers]

Are you looking to get it done to pass building control or are you looking for trouble free future? (ie is it your own place).
If the former, do whatever they let you get away with.
If the latter, dig down and do it properly. The “least work” robust way is to dig right down at manhole so as to enter horizontally at sewer pipe level. A couple of feet away from this you can then employ the ‘back drop’ method with no worries - better if you use a nice slow bend at the base of back drop and you also need to add rodding access to this (basically at top of back drop use a branch rather than bend, with rod point on vertical section).
I did this at home 7 years ago and no problem since (why did I write that down...)

Hi, thanks for the reply. It is at a client's so belt and braces and with regs

 

[Ben-gee]

Get your spade out then!

 

[mutley racers]

Called them and they say I can do internal backdrop as long as there is still room for access. Not sure what space it is you need but it is a standard manhole drain so I would have thought big enuf

 

[Ben-gee]

Don’t forget they are satisfied if there is access to jet it, expensive, better if there is access to rod it.

 

[NickH]

How much space you need depends on the depth of the manhole. Over a certain depth you have to have enough space for a "man" to get down the hole so in theory an internal backdrop might encroach on that.
How deep is the manhole ?
A normal rest bend isn't a short radius bend, two different things. Use a rest bend as they are easier to rod.

 

[mutley racers]

Thanks for the advice so far guys.

So reading up on drainage, it is most likely I can do an internal backdrop as the man hole is about 600 x 900 and about 1.6 metres deep.

Upon reading, it says I need a flexible connection 150mm away from where the pipe enters the manhole. Does anyone know where I can find one of these?

Also, what are the fittings called that you cut into the benching? Or can I just cut a spigot elbow in half to create this open channel?

Cheers

 

[mutley racers]

Another question guys. I will be running a new toilet soil pipe out of a pitched roof to the stack. Do I use a pitched roof slate but reverse it so the pitch is pointing down and then I shall get the slope to the toilet? Or do I use a flat roof one

 

[Burger]

Another question guys. I will be running a new toilet soil pipe out of a pitched roof to the stack. Do I use a pitched roof slate but reverse it so the pitch is pointing down and then I shall get the slope to the toilet? Or do I use a flat roof one

How high is this toilet? Any photo or diagram of proposal?

 

[mutley racers]

It is in the loft. I am replacing the Macerator there. No photos as they are all on my old phone. I priced up this job a Yr ago

 

[Burger]

It is in the loft. I am replacing the Macerator there. No photos as they are all on my old phone. I priced up this job a Yr ago

Are you taking the macerator out? If so, is there no provision for taking svp through the wall?

 

[mutley racers]

Yep, I am taking the macerator out. The soil pipe is going to have to go out through the roof slates as it is in the loft.

 

[mutley racers]

Ok, managed to dig them out.

 

[Burger]

Ok, managed to dig them out.

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Oh ok, it’s more sense from that. So you propose a soil pipe somewhere? Might be easier to run pipes out of eaves?

 

[mutley racers]

Ok I a make a it’s more sense from that. So you propose a soil pipe somewhere? Might be easier to run pipes out of eaves?

Do you mean out through the soffit board then? Still need to install the vent through the roof though. Unless a house in that row has a vent on it so I could get away with a durgo.

Would it be OK to run the bath and basin waste into the toilet branch or will the BCO want to see it going into the main stack?

I want to run the soil pipe next to the down pipe.

 

[Burger]

Do you mean out through the soffit board then? Still need to install the vent through the roof though. Unless a house in that row has a vent on it so I could get away with a durgo.

Would it be OK to run the bath and basin waste into the toilet branch or will the BCO want to see it going into the main stack?

I want to run the soil pipe next to the down pipe.

Yes through soffit, providing it’s not asbestos. Why would your bent need to go through roof? Could take it 1m higher than gutters on an offset? Do you mean bath and basin in the same stack as wc? If so, i don’t see an issue.

 

[mutley racers]

Yes through soffit, providing it’s not asbestos. Why would your bent need to go through roof? Could take it 1m higher than gutters on an offset? Do you mean bath and basin in the same stack as wc? If so, i don’t see an issue.

Hi, I do mean into the same branch as WC? Which then goes into the stack through the soft rather than 3 pipes coming out of the soffit and into the stack.

Also, any ideas on what the flexible connection should be before the pipe enters the manhole?

Thanks for all the help by the way.

 

[Burger]

I would go with the length of soil connecting to wc pan, then a bossed connector to take bath and basin all on same horizontal yes, then only one pipe outside. Not sure what flexible connection you’re on about? However if it’s what I think it is then a soil bend, piece of pipe and another soil bend at the bottom.

Short bossed connection Short Boss Pipe 110mm Black

You’re welcome for the help, it’s what we’re here for.

 

[NickH]

With regards to the manhole and what fittings etc. to use, in my experience it will save you a lot of aggro if you can get the building inspector out and go through it with him first. In theory they all work to the same rule book but in practise they all have their own ideas and some can be much harder to please than others.
Get the guy (or girl) out and get them to agree exactly what they'll be happy with, then you know your not going to have any issues with it.

 

[mutley racers]

With regards to the manhole and what fittings etc. to use, in my experience it will save you a lot of aggro if you can get the building inspector out and go through it with him first. In theory they all work to the same rule book but in practise they all have their own ideas and some can be much harder to please than others.
Get the guy (or girl) out and get them to agree exactly what they'll be happy with, then you know your not going to have any issues with it.

Hi Mate and thanks for the reply.

The thing is, I believe every time they come out they charge you don't they?

 

[mutley racers]

Can someone explain to me what this refers to as a suitable material?

 

[mutley racers]

Can I sift the soil through a 10mm sieve and that will be fine?

The manuals for these pipes say the trench needs to be pipe diameter plus 300mm. In some places it is impossible to achieve this due to foundations and other pipes etc.

 

[NickH]

The building Reg fees are based on the type and/or cost of the works your doing. It covers any necessary inspections and advice.

 

[mutley racers]

So all the worry over nothing really. The building inspector came to inspect and really was not fussed at looking at the pipe before it was buried. He didn't I had to put in a 45 underground which he did not like. Made me change it for a 90 which I thought was strange.

I had a labourer turn up on the 1st day to dig the trench, he couldn't come in to backfil due to sore hands and back. I called another one who said he was just around the corner on the bus and he never and showed up and then a 3rd one who was on his way never made it. You just cannot get the staff!

Strange thing, I have never had a leak on a solvent weld fitting and I had 2 tiny weeps on two fittings. Strange.

 

[mutley racers]

Thanks for all the help guys

 

[ntipp]

When digging your trenches make sure that they adhere to building regulations, which means that the top of the pipes must be at least 300m deeper than ground level.