Installing Underground Drainage

[milbo1990]

This follows a post I made a few months ago when I was at the planning stage...

I've now got my trenches dug out and all my parts are coming tomorrow. Plan is to pour in my pea shingle level and achieve the gradient I need (1:40) by packing under the drainpipe with packers to achieve the desired angle. Planning to do this because I think it'll be more accurate than trying to get the right gradient with the pea shingle.

Is this ok? Or can you think of a better method?

Also, is it alright to use fairy liquid in place of the expensive pipe lubricant?

Thanks in advance!

 

[Blagard]

Use the pea shingle, it is fairly ease to get the falls right with it by simply working the pipe into the bed so start with the pipe just a little higher then when you get the bedding right put in the surround and test it for water tightness before backfilling the rest of the trench.

I am not sure that fairy liquid is cheaper but in small quantities it probably is, because you use the fairy elsewhere and don't waste any, so carry on.

 

[noseall]

Do not put pea gravel anywhere near the pipes until they are laid.

Fit each pipe run then pack them up on bits of brick or wood or owt to get your falls.

Then pour the pea gravel in around the pipes, only half covering them until building control has had a squint.

You will not be able to 'work the pipes into' the pea gravel.

Use fairy, not a problem.

 

[Blagard]

Do not put pea gravel anywhere near the pipes until they are laid.

Fit each pipe run then pack them up on bits of brick or wood or owt to get your falls.

The only hassle I find with that (which is the way most small clay drains get laid) is that with PVC drains they move around too much when you pour your bed in and work the gravel under the pipe to get rid of the small voids that happen if you just tip it in. You can work the pipe into a bed but the bed needs to be only slightly higher to start with, pretty much at invert levels. Otherwise I agree it is near impossible to work it down, my bad for not making that clearer.

I didn't check with the OP on the material being used and dangerously assumed he would be using PVC as it is a DIY forum.

From the drainage videos I have seen, clay being rigid with flexible joints always looks good with no noticeable displacement. PVC on the other hand looks like a rollercoaster, although it was laid the same way. On low falls getting sections with a backfall is visible by the "puddles" seen.
I thought I would mention this as this comes from a site where every drain had to be CCTV'ed as part of the specification. So since seeing that I would not do it the same way as clay

 

[noseall]

The trench must be clear and you especially do not want to be push-fitting pipes together with the potential for small bits of gravel to get in the way.

 

[limerockconstruction]

Use fairy, not a problem.

I don't remember the science behind it, but I was told that fairy liquid wasn't too good for rubber over time, and silicone spray isn't prohibitively expensive, especially when you buy it in amongst an extension budget.

 

[noseall]

If fairy liquid had the potential to effect rubber seals then god help all the drainage in the uk.

There are far more aggressive products that get put down drains.

Whilst the silicone spray is brilliant, it does have the rather unwanted effect of prolonged lubrication. What this means is that the pipe joints remain very slippery long after installation.

This can mean that the joints are easily pulled apart if the pipes are interfered with, whereas fairy dries up after a while. Can work to your advantage, agreed. But it can be a pain also. I find myself forever checking that the pipes are all slotted 'home'.

 

[Ian H]

I would get your falls by laying the pipe in the trench then put 4 bags of gravel under each 3mtr length. You will be able to sit your level on the pipe and adjust it before you gravel the lot.

Don't pack it up on bricks or wood unless you are going to remove them as the gravel goes in.

 

[CHarr]

Most manufacturers say very clearly that you should NOT use household detergent to lubricate push-fit drainage pipes. Builders do it all the time. Draw your own conclusion.

 

[noseall]

Don't pack it up on bricks or wood unless you are going to remove them as the gravel goes in.

Why? What is the problem with leaving packers in?

I would get your falls by laying the pipe in the trench then put 4 bags of gravel under each 3mtr length. You will be able to sit your level on the pipe and adjust it before you gravel the lot.

How do you propose getting gravel under pipes without the pipes being packed up.

 

[themiddleagedun]

It's the best way...

 

[Ian H]

The pea gravel (pipe bedding) is all you need, I believe the official term is 'free flowing to BS???' But in my experience putting anything large/solid under or on top of a drain is not good.

You get it under the pipe by simply stabbing/chopping it in with your spade.

 

[noseall]

But in my experience....

Which is?

Packing pipes is a tried and tested method.

The packers only need be of modest size usually a half batt.

You get it under the pipe by simply stabbing/chopping it in with your spade.

I don't think you have a clue, either that or you are a cowboy.

 

[Ian H]

Ha ha!!! I have being doing drains since 2004, that's experience enough thanks.

I have seen plenty of displaced joints caused by people using packers under plastic and clay pipes.

If packers were proven the would be made and sold my Osma etc.... How you have labeled me a cowboy and said I don't have a clue has given me a good chuckle so thanks for that.

What do you do with the gravel under your pipes, do you just pour it in then backfill?

 

[noseall]

The packers become obsolete once the pipe is surrounded in pea gravel, as 97% of the pipe surface is grabbed by the gravel.

What you say it total bo lax and completely irrelevant.

Ha ha!!! I have being doing drains since 2004, that's experience enough thanks.

And learned very little in the process.