Bath trap/waste options

[Grabags]

Hi Everyone,

I am putting a bath into a bathroom with limited ceiling height so am trying to get the bath as low as possible. Currently the bath waste will be at the height of the plywood floor which means a bigger hole and less structural support. Ideally I would like it to be below the floor, reducing the hole size in the plywood to just the pipe diameter, and allowing the waste pipe to run under the floor too.

The question is- can I add in a small (say 6"/150mm) vertical drop between the bath plug/waste and the trap?

Another issue I will have is once under the floor, to get around a joist without drilling any holes I will need to drop a further 6"/150mm over approx 3'/900mm, after which it will join a regular drop (approx 1/80) waste pipe.

Are these steep drops OK for short distances or is this an obvious mistake?

Thanks in advance your your help!

 

[Harvest Fields]

Any pictures of what you have already?

 

[Grabags]

The bath is to replace a shower which I've already taken out but here's what is left. The shower was connected under the joist via a flexi pipe shown. I intend to replace the flexi with solid pipe but need to run this for a length until it is below the joist. Forgive my artwork but I've tried to draw a representation of what I had in mind as a solution (the perspective just to show drop etc- the bath actually runs perpendicular to the 3''x9'' joists). Ive also attached some pictures of the new bath and feet arrangements to show how the trap wil be at floor height unless I can find a solution. Thanks for taking a look!

 

[ShaunCorbs]

why not use one of these?

*

www.wavin.com

 

[Grabags]

Interesting. Would that run vertically down then? (I’ve only got about 45mm between the floor and bath so if it’s thicker than that it won’t fit horizontally)

 

[ShaunCorbs]

yes vertical approx 50mm dia

 

[Grabags]

Sounds perfect! If attached directly to the waste it’ll probably help solve my other problem (dropping below the joist) too!

Cheers Shaun

 

[ShaunCorbs]

trap

adapter

will fit straight onto the bath outlet dont buy them from my links go to your local plumbing merchants be a bit cheaper

 

[Grabags]

Ok cheers (silly question but just to make sure- I take it the trap goes first and the adapter is to get the run back to horizontal?)

 

[ShaunCorbs]

Depends how your doing it

Vertical it should screw straight onto the bath waste

Horizontal you need the adapter which screws onto the trap and then goes onto the bath waste

Hope it makes sense

 

[Grabags]

Ok gotcha- thanks again Shaun.

 

[toucan]

45mm between floor and bath ? How are you going to install the Hep ? and what about future access. Best to raise bath a bit to allow access and live with head height, fit trap in a hole in floor easier to install.

 

[Grabags]

45mm between floor and bath ? How are you going to install the Hep ? and what about future access. Best to raise bath a bit to allow access and live with head height, fit trap in a hole in floor easier to install.

Hi Toucan,

Yes good points- future access is an issue of concern and install was going to be slightly tricky (although currently with floor up adjacent it could be done).

What do you mean fit trap in a hole in the floor? That’s where it was going to go (straight down vertically). Do you mean to run the trap horizontally above the floor, then after the trap run vertically down into the floor?

 

[toucan]

Hi Toucan,

Yes good points- future access is an issue of concern and install was going to be slightly tricky (although currently with floor up adjacent it could be done).

What do you mean fit trap in a hole in the floor? That’s where it was going to go (straight down vertically). Do you mean to run the trap horizontally above the floor, then after the trap run vertically down into the floor?

I meant normal p trap but you could run the hep horizontally, P trap costs
much less than Hep trap and knuckle adaptor. Bigger floor opening required but shouldn't be an issue assuming ply well supported in vicinity

 

[Grabags]

I meant normal p trap but you could run the hep horizontally, P trap costs
much less than Hep trap and knuckle adaptor. Bigger floor opening required but shouldn't be an issue assuming ply well supported in vicinity

I suppose I could install noggins either side of the hole, but one concern I had with a regular P trap was that I’d need to install a near vertical drop just after it to get under a 9’’ floor joist and connect to the existing waste run. I also bit the bullet and bought a Hep yesterday (yes quite pricey and that was without the knuckle adaptor!).

I’ve been from pillar to post with the space restrictions so any solution is seeming like a compromise.

 

[Grabags]

I probably should have mentioned- the bath is a double sided one so the drain is in the middle, but in line with the centre foot, hence trying to limit holes in line with it.