Drain smells coming into house (with diagram)

SCarey84

Had this problem for ages and need help. I live in a 3 story house with 2 separate 4" drain stacks. 1 drain stack goes right up into the attic and turns in line with the roof. Another drain stack goes up to the first floor, then goes up to attic via small white pipe for venting. These 2 pipes are joined together in the attic. I have a diagram drawn up i will post now if i can figure it out.
Smells are escaping into the house, so somethings not right.
Help would be greatly appreciated.
Thanks.

SCarey84

Sorry. Quite hard to explain. Diagram probably easier to understand.
https://ibb.co/j0EGZJ

landcrzr

1" might be a bit small for venting. Toilets on that stack might be drawing water down bath/shower trap, letting foul air out.
Also remember water will evaporate from traps, they should be used/filled at least weekly.

SCarey84

Maybe it's bigger than 1". I'm not too sure. Is it right though that the 2 vents are connected in the attic? and not vented out the roof. It's so strange, smells seems to appear in stairs up to 2nd floor room, not in bathroom. Head melted!!

K.Flyer

So basically what you are saying is that you have two venting stacks that run internally, both enter into the attic at opposite sides and are joined together forming an inverted V with the roof apex.
If this is the case, whoever did that had no clue what they were at.
Both stacks need to be vented out to open air. From your drawing the roof tile vents are in place, but not utilised. Until this part of the problem has been rectified first you are wasting your time trying to resolve any bad odour issues as this is going to be contributing to it, and may actually resolve it.

Del2005

Are you regularly using all the bathrooms, toilets/basin/bath etc, in the house? If you aren't then the water may be evaporating from the traps and letting the gases in.

Dtp1979

K.Flyer wrote: »

So basically what you are saying is that you have two venting stacks that run internally, both enter into the attic at opposite sides and are joined together forming an inverted V with the roof apex.
If this is the case, whoever did that had no clue what they were at.
Both stacks need to be vented out to open air. From your drawing the roof tile vents are in place, but not utilised. Until this part of the problem has been rectified first you are wasting your time trying to resolve any bad odour issues as this is going to be contributing to it, and may actually resolve it.

+1 ok this. Also make sure all traps have water in them. But as said above, that’s the main issue

SCarey84

Thanks for help all. I'll get some 50mm pipe and a couple of bends and do a job on it in the attic. I'll let you know how I get on.
Cheers.

May Contain Small Parts

SCarey84 wrote: »

Thanks for help all. I'll get some 50mm pipe and a couple of bends and do a job on it in the attic. I'll let you know how I get on.
Cheers.

your other option is to add air admittance valves to the vent stacks without having to poke through the roof.

Dtp1979

May Contain Small Parts wrote: »

your other option is to add air admittance valves to the vent stacks without having to poke through the roof.

No.
The only let air in. An open vent works both ways

K.Flyer

May Contain Small Parts wrote: »

your other option is to add air admittance valves to the vent stacks without having to poke through the roof.

In the drawing it shows two unused roof tile vents, should be easy to hook onto them.

SCarey84

Right. Got a bit of time and salvaged some materials to do some pipe work in the attic. Certainly not what I envisioned, it's horrible looking, but it is all very well siliconed and sealed together. See pictures attached. Ignore the old white flex pipe. Not in use any more. FYI I don't claim to be even an amateur plumber. Haha. Sure I used a mixture of fusetite, duct tape, insulating tape, fixing band and random bits of pipe and bends. Seems fairly airtight though.
Wait and see now if the smell comes back. It's happening in random plumes. So if all is clear over the next week I'd say it worked.
Thanks again for help.

SCarey84

https://ibb.co/bEGEWK
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https://ibb.co/ndtuWK
https://ibb.co/d2kKyz
https://ibb.co/fXJiQe
https://ibb.co/dYYiQe
https://ibb.co/ep3Hke
https://ibb.co/nJTYQe
https://ibb.co/mR0PWK

K.Flyer

Bit hard to make out exactly what you have done, but it looks as though the vent pipes represent a roller coaster going up and down.
The pipes or flexible tubes should always follow and upward only gradient so that it leaves nowhere in the pipe run for condensation to build up, possibly blocking the vent.