Why don't most drainage suppliers show the invert level loss on their product drawings?

[Alan Ambrose]

I would think that's important info, particularly if you're 'fall challenged'?

 

For the 2nd product below, I'm guessing it's ~75mm as this is 225mm twinwall into 300mm twinwall and the tops of the pipes look roughly in line, but whatever ... ?

 

 

[ToughButterCup]

I'm really no expert but if you are thinking about the odd few mm over the width of an IC, then set the inspection chamber slightly lower at lower one end.  Two or three millimeters is not going to make any difference

[Dave Jones]

what are you considering fall challenged ?

[Russell griffiths]

It is annoying, but set your main run through as the lowest run and side branches will step up from that. 
 

I know that doesn’t help if your trying to design something and need measurements now. 

[saveasteading]

You are right. There is no excuse for this lack of info. 

It would matter a lot if it is tight connecting two fixed end levels.

Also, for a long run, the total depth can add up to become unnecessarily deep.

Can you put the main runs in a line and still get branches to connect properly at the higher level?

Go to your merchant armed with a spirit level and tape.

[ETC]

……or use Wavin ICs……all channels at the same level…….

[Alan Ambrose]

>>> @Dave Jones what are you considering fall challenged ?

 

About 45m as the crow flies (these can fly straight-ish but not dead straight) with strictly speaking only 35cm of fall from GL to IL of culvert ... including the drops in gullies, inspection (x2 maybe x3) and a join into 300mm twinwall. This is for rainwater & SuDS set-up.

 

@ETC - thanks for the tip on Wavin

 

 

[Dave Jones]

7mm of fall per m, would be an issue for foul as 13mm per M is limit for 110 pipe, i believe you can go shallower if you use larger diameter pipe though. 

 

For grey that has no solids you could lay it flat and not have an issue.

[Alan Ambrose]

For anyone with a similar problem - I've taken to importing manufacturers drawings that don't have invert levels or falls into CAD, scaling the image to the largest dimensions shown on their drawing and then reading off any measurement I need.

[saveasteading]

On 26/06/2024 at 14:12, Dave Jones said:

 

 

For grey that has no solids you could lay it flat and not have an issue.

 

@Alan AmbroseDon't do that.

 

Instead see all the information in document H of the building regulations. 

Free to download .