Washing machine standpipe trap under floorboards, is it possible?

[johnny2007]

Hi, I come across a kitchen design that doesn't give much room for manoeuvre and I have to run the new washing machine waste under the floorboards.
Rather than use a conventional standpipe and trap with compression fittings, can I build my own with solvent weld fittings so to have no chance (or should I say less chance) of a leak?

 

[Madrab]

Of course you could but a trap isn't just for the water seal, it is so it can also be cleaned if and when needed. That needs to be kept in mind.

 

[johnny2007]

I know, but being under the floor it will never be accessed directly.
If needed to be cleaned it would have to be rodded.

 

[JohnD]

Why don't you think you can have a trap above the floor?

 

[johnny2007]

Because there's a brick step in the wall behind the wm and space just for a standpipe in a corner, but not for the trap.
I don't want to start breaking walls as i'm sure it would uncover more trouble.
I thought that maybe I could do the standpipe and trap with 50mm weld pipes so to avoid any potential blockage and make rodding easier if needed.
What do you think?

 

[Nige F]

How about a Hep V O waterless "trap" in the upstand part just above the floor ?

 

[John D v2.0]

Mcalline do a running trap which would be better than solvent weld if you want to dismantle.
The trap should be accessible though and directly after the machine, so you might have to stretch that definition
https://www.screwfix.com/p/mcalpine-running-p-trap-white-40mm/47605

 

[johnny2007]

It won't fit unfortunately.

How about a Hep V O waterless "trap" in the upstand part just above the floor ?

Didn't think of that.
Thanks.
It will work a treat.
I'll go for this one:
https://www.toolstation.com/mcalpin..._HVJV5p02vmg-81gOmnzRjU--nUKkq9BoCshsQAvD_BwE

 

[Nige F]

Didn't think of that.
Thanks.
It will work a treat.
I'll go for this one:

You'll need a Mc Alpine 40mmT31U to adapt the threaded end so both ends go onto pipe. Product code 72306. Job's a good un PS when you do the pipework use swept bends - not those **** 90 degree things that can catch debris

 

[johnny2007]

You'll need a Mc Alpine 40mmT31U to adapt the threaded end so both ends go onto pipe. Product code 72306. Job's a good un PS when you do the pipework use swept bends - not those **** 90 degree things that can catch debris

Definitely.
Done quite a lot of plumbing labouring and stole lots of secrets.