Bathroom extractor ducting up & down

[Nde]

Hi,

I've been scouring the web and can't find any solid answer to whether this is a good idea or not (probably means it isn't!), we'd like to install a toilet under the stairs (semi detached, under the stairs) and looking at how to get ducting to the outside.

The red pipe straight under the suspended floor straight out, the only problem is the drive at some point has been increased (grey block far right) although there is a small air gap we could use or do we go up and out (green pipe) or will water ˌvapour condense and get stuck in the bottom of the ducting with no run off?

Thanks

 

[Deleted member 174758]

Yes, moisture can indeed accumulate at the lowest point. Against that, though, you shouldn't get that much moisture because a toilet isn't like a shower room. So why not go through the wall at the bottom (pink line), put an elbow on the outside and connect it to a "snorkel" vent.

At a guess air flow in drier months should be enough to evaporate what little moisture could ever accumulate in the bottom elbow. If you are really concerned about it you could always put in a small gravel soak away beneath the elbow and drill a couple of weep holes in the elbow. Providing the drive is adequately drained away from the house and you have a soak away that should deal with any water. Personally, if your house is centrally heated, I very much doubt you'll need the weep holes

If you are wondering where to get a snorkel vent, they are used as anti-flood protection and are sold by a lot of builders merchants. The ones I have used were made by made by Donite Plastics and sold through Snorkelvent (I live in a flood-prone district where these get installed over air bricks quite a lot), but there are a few other brands on the market. To connect your ductwork to these you may need to do a bit of modification or maybe terminate your ductwork in an airbrick insert

 

[Nde]

Thanks for the info, didn't know those external snorkel vents existed! The house is centrally heated so like you say probably being over precautious for a small toilet extractor fan

 

[foxhole]

Thanks for the info, didn't know those external snorkel vents existed! The house is centrally heated so like you say probably being over precautious for a small toilet extractor fan

You title contradicts your question, is it a toilet or bathroom , toilet does not produce any moisture in vent.