Which waste pipe route is best?

[mpajones]

Hi guys,

I'm fitting a bathroom for - wait for it - the mother in law over this Christmas, and need help on deciding the best route to pick for the basin waste. Neither option seems massively appealing and would therefore appreciate some advice.

The two options (with pics attached) are as follows:

Option 1. Run the waste down, under the floor between the joists (which run across the narrow width of the room), bore a hole in the exterior wall and route the pipe along the outside of the wall and into a hopper (that I would also add to) the guttering downpipe.

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• mpajones
• 22 Dec 2009
• 1

Option 2. Run the waste pipe through the stud wall behind the basin and along the entire length of the wall (though holes in the the studs I guess), round the back of the toilet (there will be a boxed section here, so this bit is fine) and into the soil pipe.

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• mpajones
• 22 Dec 2009
• 1

My questions are:

a) Are there any regs issues with either option that you know of?
b) Which would be easier to implement?
c) If I run the waste through the studs, is it just a question of boring 35-ish mm holes and feeding the waste pipe through, or do I need to reinforce this wall at all?

Thanks for your help
Matt

 

[dextrous]

Think option 1 is better. For those distances to would be wiser to use at least 40mm pipe anyway. When the pipe comes throughtthe wall fit a Tee with a rodding point as a matter of course.

 

[Hugh Jaleak]

Also depends on where the rainwater goes, you shouldnt really be discharging a basin into a surface drain... Whilst hoppers have their place, it is also technically illegal to fit one in this situation, (well, Building regs say so!).

 

[electronicsuk]

I think solution 2 will be a non-starter, the studs will be nowhere near thick enough to bore a hole through for a waste pipe without losing a lot of structural integrity.

Your first idea sounds more sensible, but again care will be needed in selecting where to drill the joists, and as has already been mentioned, discharging foul water into what may be a rainwater drain isn't too smart either.

Perhaps you would be best just to box the pipe in and run to the soil stack. If you must have a completely flat wall, you could always build another stud wall in front of the existing one to give you somewhere you run pipework, wiring, etc.

 

[jobloggs]

Possible to switch position of basin and towel rail? It might be easier to run the flow and return across under the floor than either of your stated options.

 

[dextrous]

Also depends on where the rainwater goes, you shouldnt really be discharging a basin into a surface drain... Whilst hoppers have their place, it is also technically illegal to fit one in this situation, (well, Building regs say so!).

Missed that one However, all need not be lost - while you've got the core drill, you may be able to pull the waste back into the soil stack

 

[neds]

For 32m pipe those sort of distances you are asking for trouble. Fit an anti-Vac trap as a matter of course, better still as suggested go 40mm that will allow you a longer run, just over 3 meters.

Also you can't just stick a hopper onto a rainwater downpipe even if the downpipe is going into a gulley its questionable...

 

[mpajones]

Thanks guys, this is sound advice.

So it seems as though boring holes through the stud wall is probably a non-starter, and the other option is against the regs.

I quite like the idea of running the waste out of the exterior wall (option 1) and then potentially nipping it back into the the soil stack by coming back in through the wall. Creative!

Alternatively I think the most pragmatic approach will be to raise the shower tray a little, box it in along the floor on the back wall, then under the shower tray, and join in with the shower waste that's going into the soil stack.

Appreciate the fast responses...

 

[Nige F]

what room is below - with the soil pipe boxed in -

 

[mpajones]

The kitchen is below the bathroom, with the soil pipe boxed into the corner as it is in the bathroom.

Here is another stab based on the discussion so far. Move the basin onto the far wall (rather that the one with the door), add a box along the wall of height approx 130mm, and route the basin waste under the shower stand to meet with the shower waste and feed into the soil stack inside the room.

My thinking is that the box would be approx 130mm high (to be flush with, or at least no higer than the top of the shower tray), use 40mm pipe (due to the length), and feed into the soil stack either at or just below floor level in the corner.

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• mpajones
• 23 Dec 2009
• 1

I think drop-wise, this will just about achieve 18mm/m, and of course the basin would have the initial 600mm or so vertical drop to give the waste a shunt.

Tieing into the shower waste, I'm guessing an Anti-vac trap would be essential to prevent basin waste siphoning up into the shower tray (?).

Seems like quite a messy (and possibly problem-prone) solution, but I just don't know what else might be possible...

 

[Nige F]

OK -Kitchen So can you drop through the floor..above the wall units near the soil boxing ...and stab in there with strap boss