Water ingress through bathroom extractor

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    Water ingress through bathroom extractor

    Our letting agent informs me that the extractor in our tenanted flat has stopped working. It was inspected today and we've been told that it has blown because water has found its way into the unit. I can believe this as when we bought the flat earlier this year I replaced the extractor as it was not working and heavily corroded inside; I mistakenly thought this was because of an historic leak.

    The fan vents vertically through a rigid plastic pipe and out onto the roof, where it is covered by a cowl. The reason given for water finding its way in is that the cowl is one designed for a soil pipe and not for an extractor set-up such as ours. Having looked on the net I'm unable to see any distinction between the two. Can anyone with a bit more knowledge than me tell me whether the diagnosis is plausible? Obviously you won't be able to say for sure without seeing it yourself!


    If it's vertical, then rainwater falls down verticaly ( basicly ) so you need a "Hat" on top of the vertical outside pipe.

    If it's a soil pipe end, it may have slots in it to allow rain to come in, which does not mater in a soil pipe, cos it goes down to the sewers.

    A cone shaped hat thingymabob is what you need, so the pipe sticking up, looks like an arrow.



      Thanks Ram - sounds logical.


        The wired looking type 1 is for soil pipe use and is known in the trade as a bird cage,theres a couple of options for the one you require for a vent like a mushroom cowl.


          Thanks Icehammer. This was what confused me as I can see the cowl from the road and it is indeed one of the 'mushroom' types. As such, it should be OK? Another possibility, having done a search on the net, is that moisture is condensing in the pipe and running back down into the fan. However, the fan was a brand new Vortice fan, which I always thought was a good make, and according to the spec has the requisite power for the job. I guess I'll need to get someone in to have a look at the roof and make sure there is no water getting in where the pipe exits the roof. As the flat comes with Premier guarantees it will be interesting to see if any of this is covered...


            Originally posted by Royal_Borough View Post
            is indeed one of the 'mushroom' types.
            May be moisture is condensing in the pipe and running back down into the fan. ...
            Or pipes letting in water
            If the vent pipes are letting in water, sealing may cure the fault.

            Another problem may be as you suggested, the pipe is too long, moisture collects in after fan has blown moisture laden air up there, or even hot air up there, which will cause condensation to form, and slowly drips onto the fan, or condenses onto the fan.

            If the fan is not used often, then condensation or leaks will not be removed fully.
            If after all avenues have been exhausted, then it may be a question of putting the fan on, if only to blow out condensation, which is difficult on a vertical pipe, and also takes time to slowly remove condensation ( it does not disapear instantly the fan is switched on, but over say 15 / 20 minutes with your setup.

            Or, if there is no other way out of the problem, replace the fan every time it expires.


              Thanks Ram. On reflection I'd be surprised if it's condensation because the pipe from extractor to open air is very short as the bathroom is built into the eaves. It seems that condensation is mainly a problem with longer lengths of pipe and where it passes through a cold loft voidr. As this problem has manifested now, while the outside temperatures have been very mild, then I suspect it's something else.

              If it were my own house then I could spend some time investigating but it's a rental and I live many 00s of miles away. As such I shall have to ask someone to take a look and hopefully come up with a solution...


                If this vent is from a bathroom which does not have a large amount of 'family' use I might be tempted to vent into the loft void and be done.

                I have done this in a few places myself and nothing terrible has ever happened - I usually buy cheapish fans from Toolstation and they last well.

                Freedom at the point of zero............


                  Hi Interlaken. I can see the sense in this as light use would not cause enough damp to trouble a large loft space. Unfortunately this will not work for me as there isn't a loft void at all. The top floor of our apartment (it's a duplex) is right under the roof - so there's some plasterboard, the requisite insulation, and then the roof. Interestingly I've managed to speak to the guy who was renting the flat next door, which is identical in spec and layout. He had exactly the same problem and informed the landlord. The maintenance company they sent round said that it was part of the design for water to trickle back into the unit! Huh?? I'm not sure if they realised that the tenant was actually a surveyor and so he probably knew that this was garbage. Anyway, his final word to me was that he left it permanently off as it kept tripping his electrics. So, painful and expensive as it may be, I think the whole system needs a re-think. If my current tenants stop using it for the same reason then I suspect the ongoing moisture will store problems for me further down the line...


                    I had the exact same problem myself with a tenanted property; here's how I solved mine (which is not to say there aren't multiple possible causes for it).

                    This fan had a near-vertical 4" duct going up from the roof space above the bathroom ceiling and passing through the tiled roof via a special tile fitted with a rubber gasket something like this:


                    I discovered that this gasket could 'flip' up or down while the duct was being fitted (the duct would be slid up and down while getting the position right).

                    In this case, the gasket had got flipped 'down', meaning that instead of a downward sloping surface for water to run off, there was a recessed doughnut-shaped area around the duct for rainwater to collect, and any imperfection in the seal allowed water through, where it ran down the outside of the duct and into the fan.

                    I liberally greased the deal with silicone grease, and ensured it went back in the 'up' position; have had no more trouble since.

                    Definitely something to mention to the maintenance guy as a possibility to check, anyway.


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