Longest available foul drain pipe section.

[epsilonGreedy]

 I am contemplating running a foul drain through the block & beam suspended floor void and then out through the foundation on the other side of the house plan view. The longest pipe section i can find is 6m. Do such pipes come in longer sections, I ask because I want to reduce the number of joints in such an inaccessible location?

[PeterW]

6m is the max but may be on special order as 3m is the norm these days. 6m is also a pig to get at the right fall as you can easily get 150mm flex in a length if you pick it up in the middle. 

[epsilonGreedy]

2 minutes ago, PeterW said:

6m is the max but may be on special order as 3m is the norm these days. 6m is also a pig to get at the right fall as you can easily get 150mm flex in a length if you pick it up in the middle. 

 

 

Ok, I would be looking for a 10m section in order to get a joint free horizontal run, maybe my time would be better invested researching quality components and jointing techniques.

 

I reckon this drain pipe will be mid air which implies some special support.

[PeterW]

10m doesn’t exist in 110mm uPVC 

 

It needs supporting either on brick or block piers or supported from under the floor so you need that detail sorted before the beams go on if you are having beam and block. 

 

Is it the best route to go under the floor - what is on the BRegs drainage plan..??

[epsilonGreedy]

33 minutes ago, PeterW said:

It needs supporting either on brick or block piers or supported from under the floor so you need that detail sorted before the beams go on if you are having beam and block. 

 

 

I prefer the notion of hanging this pipe off the floor beams because in my head if it is sitting on ground supports and there is a touch of heave/subsidence this could result in the jointing at the bottom of the stack coming under stress.

 

33 minutes ago, PeterW said:

Is it the best route to go under the floor - what is on the BRegs drainage plan..??

 

 

The guy doing the BC diagrams is not aware of the big picture foul drainage plan particularly the main sewage interconnect so the finer details will likely evolve beyond the BD diagram.

Edited June 25, 2018 by epsilonGreedy

[PeterW]

29 minutes ago, epsilonGreedy said:

The guy doing the BC diagrams is not aware of the big picture foul drainage plan particularly the main sewage interconnect so the finer details will likely evolve beyond the BD diagram.

 

That won’t pass regs then as you are required to have the drainage plan drawn as they need to pass it to the sewage provider. 

 

I would get that sorted - inverts are needed to make sure it’s right before you start ..!!

 

 

[epsilonGreedy]

11 minutes ago, PeterW said:

That won’t pass regs then as you are required to have the drainage plan drawn as they need to pass it to the sewage provider. 

 

 

Ok. I had previously got the impression that a building control inspector has the authority to interpret things as seen onsite and approve even if the build deviates from the published official BC diagrams. From what you say sewage drainage is different. 

 

15 minutes ago, PeterW said:

I would get that sorted - inverts are needed to make sure it’s right before you start ..!!

 

 

Today's mission is levels and drainage. It all works in my head based on my own pre plot purchase diy water level survey. Just need to firm things up with some real topographical figures.

 

If there is an extra 0.5m of gradient going spare then I could run the foul drain outside the foundation perimeter at the cost of 3 extra turns and rodding points.

 

The Passiv Slab fraternity seem relaxed about routing foul drains across the property's foundation plan but it would be good to hear those with suspended ground floors have done the same.

[Mr Punter]

I like the base of the stack radius bend supported on the foundation on mortar / concrete.  You can support the pipework by suspending from the beam and block, but I would want to see stainless banding for this https://www.toolstation.com/shop/Construction+Materials/d210/Builders+Metalwork/sd2797/Stainless+Steel+Banding/p48657.  6m max for pipework because plastic expands / contracts and 10m is impractical.

[PeterW]

33 minutes ago, epsilonGreedy said:

Ok. I had previously got the impression that a building control inspector has the authority to interpret things as seen onsite and approve even if the build deviates from the published official BC diagrams. From what you say sewage drainage is different. 

 

Is this private or council BCO..??

 

The problem you have is that if you get a different inspector then you can get real issues with interpretation of the regs - just ask @curlewhouse or read the blog. 

 

I am also a bit concerned that as this is your first build you are putting a lot of trust in this “wise owl” builder who is advising you. I would question :

- do you have a contract with him..?

- what is his remit ..? 

- does he carry PI insurance ..?

 

Builds rarely go smoothly and you are placing a lot of trust in people with whom you have no contractual relationship with if things go wrong.

 

For example if the drains are too high at the sewer connection, your only option is to dig out the underground pipework and start again. Worst case is you have to put a pump in as you can’t make $h!t flow up hill on its own. Who pays for that ..?? Wise owl said it was ok, but who checked ..? Who put them in ..? BCO may want 1:40 not 1:80, but without plans to pre-approve and get answered then you are in no mans land and in a world of (expensive) pain. 

 

You’ve got a dig date and a concrete pour booked but not a fully signed off set of BRegs plans ..? What if the plans throw up something that cannot be built (it happens, just ask @Hecateh about her balcony...) so you need to change it. It cost a little time and £100-200 to get changes made on paper, digging our drains and sorting cast foundations could cost you thousands. 

[Mr Punter]

I would only run drainage under the slab where it was not possible to do otherwise.  If you can achieve a min 1:80 fall by running outside, do this.  You can change direction with an IC.  The biggest financial risks in housebuilding are foundations and drainage.

Edited June 25, 2018 by Mr Punter

[epsilonGreedy]

14 minutes ago, PeterW said:

Is this private or council BCO..??

 

 

Private.

 

15 minutes ago, PeterW said:

Builds rarely go smoothly and you are placing a lot of trust in people with whom you have no contractual relationship with if things go wrong.

 

For example if the drains are too high at the sewer connection, your only option is to dig out the underground pipework and start again. Worst case is you have to put a pump in as you can’t make $h!t flow up hill on its own. Who pays for that ..?? Wise owl said it was ok, but who checked ..? Who put them in ..? BCO may want 1:40 not 1:80, but without plans to pre-approve and get answered then you are in no mans land and in a world of (expensive) pain.

 

 

There is no sewer connection yet, just scheduled works to dig the road and create a new mains sewer spur onto the development for two plots.

 

It is 27 meters from my foundation (foul drain location) to the sewer connection point to be established. Ground level at the sewer connect is the same as my DPC so in effect the ground level at the new sewerage inter connection is 0.5m above the bottom of my most distant soil stack.

 

36.5m x 0.02 = 0.73m fall at 1:50.

 

Then add 0.5m for the starting depth of my soil stack and my foul drain arrives at the sewerage interconnect 1.23m deep. I have 150mm to spare so that could be 1.08m. At 80 to 1 the depth needed reduces to 0.8m.

 

There is an alternative simpler route for a natural gradient driven mains sewer connection that will cost another £2000. Either way I get a working foul drain at my foundations for between £3500 and £5000 which is not bad.

 

All this complexity will be resolved before I get my footings to dpc.

 

 

[PeterW]

15 minutes ago, epsilonGreedy said:

Either way I get a working foul drain at my foundations for between £3500 and £5000 which is not bad.

 

Is that including the sewer connection..??

[Temp]

You could always pressure test your joint before burying it or even install a second backup run in parallel in same trench.

 

You can get 110mm OD HDPE in 50m coils ...

 

http://www.abwplastics.co.uk/excel-pe100-water-pipe-blue-110mm-od---coils---sdr17-20151-p.asp

 

Not sure about shorter lengths. May not lay flat easily.

 

[epsilonGreedy]

5 minutes ago, Temp said:

You could always pressure test your joint before burying it or even install a second backup run in parallel in same trench.

 

You can get 110mm OD HDPE in 50m coils ...

 

http://www.abwplastics.co.uk/excel-pe100-water-pipe-blue-110mm-od---coils---sdr17-20151-p.asp

 

Not sure about shorter lengths. May not lay flat easily.

 

 

Can a foul drain use such flexible HDPE pipe?

[PeterW]

Just now, epsilonGreedy said:

 

Can a foul drain use such flexible HDPE pipe?

 

Not in blue, but can in black however that would be roughly double the price of standard UPVC and would need terminating correctly.

 

It would also be a pig to unroll and get flat - probably have to concrete it in.

[Mr Punter]

5 minutes ago, Temp said:

You can get 110mm OD HDPE in 50m coils ...

 

This is very difficult to work with without specialist equipment.  We did 50m in 90mm O/D for a pumped application.  Even on a hot day it took some serious wrestling before it could be placed in the trench.  Also you have the issue of connecting the ends which will make it far more trouble than it is worth.

[epsilonGreedy]

49 minutes ago, PeterW said:

Is that including the sewer connection..??

 

 

Yes, some economies of scale here because a few plots share the connection.

Edited June 25, 2018 by epsilonGreedy

[Russell griffiths]

Don’t even consider that mdpe

it is the most unbelievable awkward stuff to use

3m lengths with joins is the norm, don’t try and reinvent the wheel. 

The pic is a bracket you can use. 

I personally wouldn’t as no matter how close you place them over time you WILL get settlement and a small bow in the pipe

i would want a full bed under the pipe for full support, either pea gravel or a lean mix of concrete 

 

i have four toilets going in and two of them are internal so no other way but to have pipes under the floor, I do not consider it a problem 

[Hecateh]

3 hours ago, PeterW said:

 

You’ve got a dig date and a concrete pour booked but not a fully signed off set of BRegs plans ..? What if the plans throw up something that cannot be built (it happens, just ask @Hecateh about her balcony...) so you need to change it. It cost a little time and £100-200 to get changes made on paper, digging our drains and sorting cast foundations could cost you thousands. 

 

Building control plans were signed off with the balcony in place and no detail how it was to be achieved.