Horizontal soil pipe run

[TheTaffia]

Dear fellow DIYers

I am hoping to move a bathroom from the front of my house to the middle, but I don=92t really want to have to put a new soil stack in unless necessary. My question is: How far is too far in terms of a horizontal run for a soil pipe? I am proposing to have an (almost) horizontal run for about 3 metres. I=92m not too bothered about how it will look as it will run along the ceiling of an integral garage. I know that they have to have a certain fall distance per metre, I=92m just not sure what it is. I have searched the group but it seems like older posts have gone? I would appreciate any advice on the matter and no, I am not going to install a macerator - they are the devils work!

The house is semi-detached and luckily the side where the new bathroom is to go is the farthest outer wall, so it would not be the end of the world if I had to dig up outside etc.

Thanks in advance.

[RubberBiker]

Both the maximum length of a branch pipe and the minimum gradient are specified, *along with numerous other details of sanitation design*, in the building regs part H.

Min gradient is 18mm per metre

Max length is 6m for a single WC.

[Bob Minchin]

I suggest that you confirm this but 110mm soil pipe fittings installed properly give a 2.5 degree fall so I would assume this is not a bad start. I have used this angle on what must be almost 3m from a WC to the stack. It works tolerably well (since 1985!!) but the flush is poor sometimes.

I think the technical term used for this sort of consideration is referred to needing to achieve "self cleaning velocity". Basically if it is too steep the water runs past and leaves the turds behind and too shallow and the water builds up behind static turds. Whatever you end up with makes sure you have suitable access for rodding.

Bob

[John Rumm]

Between 18 and 90 mm per metre.

See table 2:

older posts have gone? I would appreciate any advice on the matter and Try google advanced search...

[TheTaffia]

Thanks for the advice all.

[gunsmith]

The fall angle needs to be a compromise to achieve self cleaning velocity for floaters and sinkers.

[Jules]

The true DIYer would have flexible elbows in the system and a motorised winch - press a button in the bathroom to set the appropriate angle for whatever's about to be flushed...