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Small Shower Room Ventilation.

I was talking to a developer this morning. His son is a sparks. The two have installed a new 4 inch ceiling fan in a small upstairs shower room that has no windows. The building roof has been renewed recently and new breathable "felt" installed under the tiles. I had previously mentioned that the roofers could install a new roof vent for the fan ducting, but nothing has been done about this.


The developer says that the son advises terminating the air duct in the loft onto a bucket to catch moisture, which I said was not acceptable.


Bearing in mind that the new roofing "felt" (membrane) is breathable, is there any reason these days not to terminate the air duct directly into the loft space with no external grille?


Z.
  • Unless the roof is an all plastic installation that does not mind getting wet, this is  a stupid idea !!.


    Assuming that the loft is cooler than the house in winter, and with insulation on the flat it will be  a lot cooler, insulation on the slope, just significantly cooler, water will condense on all cooller surfaces as damp air is added and meets objects below the dew point.


    It may work for long enough to cash the cheque for the money saved and run away, but the long term price is mould, damp and then rot.


    Please don't leave it, duct to the outside, either a vent tile or to the eaves and out but do not leave it open.


    A breathable membrane does not support the dispersal of large volumes of water vapour - it is not much better ventilated than the old tar paper of old once it had a few holes in it, and a lot less well ventilated than a traditional unlined roof. Suggest they try striking a smoke match and see how far it goes - there won't even be a breeze up there on a calm day..


    Mike.
  • Agree, a shower extract fan needs ducting to the outside, probably via the roof.

    An alternative might be available via another room and a grating in the wall.
  • mapj1:

    ... this is a stupid idea !!.


    Mike, please stop beating about the bush and let us know what you really think. (I agree.)


  • The situation is out of my hands now. I have no control over the installation. I suggested using an existing 4 inch fan hole already present in the shower room wall for the extraction of the damp air, but I was ignored.


    This is the developer that has no fresh air ventilation for log burners in two separate rooms, and a kitchen Aga. The house has been recently updated with all new double glazing so is very well sealed and airtight. And the house is to be rented out as a holiday let.


    Z.
  • Having core drill a 4” hole through the wall and having installed the fan the bathroom fitter asked why I don’t use a “box” like the other electricians.

    https://www.toolstation.com/tumble-dryer-condensing-kit/p65417
  • "This is the developer that has no fresh air ventilation for log burners in two separate rooms, and a kitchen Aga. The house has been recently updated with all new double glazing so is very well sealed and airtight. And the house is to be rented out as a holiday let."


    I hope it has an efficient means of CO detection.
  • Chris Pearson:
    mapj1:

    ... this is a stupid idea !!.


    Mike, please stop beating about the bush and let us know what you really think. (I agree.)




    Apologies if you find my style overly laid back and unclear, but please be assured that if I do hurt people's feelings it is not with intent.

    I have been known to be a bit fierce in design reviews where the background reading has clearly not been done however. ?

    this however is most unwise. and trouble awaits them in a few years time. I'm surprised building control signed off on it. Perhaps they did not see it.

    Mike.


  • Does anyone on this forum undertake this type of testing?

    Air Permeability Testing is a requirement under UK building regs (buildenergy.co.uk)


    Z.
  • davidwalker2:
    "This is the developer that has no fresh air ventilation for log burners in two separate rooms, and a kitchen Aga. The house has been recently updated with all new double glazing so is very well sealed and airtight. And the house is to be rented out as a holiday let."


    I hope it has an efficient means of CO detection.


    Yes, each room that has a fuel burning appliance has a new CO alarm fitted. But I am of the  opinion that prevention is better than detection.


    Z.


  • Sparkingchip:

    Having core drill a 4” hole through the wall and having installed the fan the bathroom fitter asked why I don’t use a “box” like the other electricians.

    https://www.toolstation.com/tumble-dryer-condensing-kit/p65417


    It makes you wonder just what alien life forms might start growing in the box after a time.