mould in bathroom

[mike the sparky]

Hi guys, I have a mould problem in two houses belonging to a landlord. Both have had a referb of sorts and both have installed a manrose 25w in-line centrifugal fan which I think may not be powerful enough. The rooms are approximately 2.5m lxdxh and have no windows or natural ventilation. One of the fans has been on a humidistat control for about 4 months and as I am aware has not turned off yet. The tenants have been advised to deep clean and remove all items that can harbour mould spores. Any advice much appreciated

 

[oldtimer]

Yep is the fan big enough and how long is the duct if its 1.5m or longer then you need centrifugal over axial also the fans take air out of the room is there a vent for fresh air to come in or a vent in the door is some old houses you could get Top Cats wallet in the space under the door.

One last point and please dont tell me I am racist I do repairs in rental properties and some of the tenants from the Indian sub continent have a LOT of bother with damp as the seem to do a lot of steam cooking throughout the day plus they will not and I mean not open a window or switch a fan on as it is toooooo cold in this country and tooooo expensive for electricity I have tried to explain that it is a culture problem and that they need to let the property breathe but to no avial

 

[Richard]

Cutting down the showering time helps tremendously. My teenage daughter is on a 3 minute timer now

I can just imagine the response if I suggested that in my house..!

 

[diditrain]

Guy i used to work with, said he had this problem in his bathroom until he fitted a heater in there. Turns it on for a few minutes after showering to dry the moist air up

 

[Richard Burns]

The extraction rate is 110m3/hr, as I am aware the bathrooms have been well cleaned with bleach and the doors are left open after showering. The main problem is two teenage daughters! Will a more powerful extractor do any good? How about a 4in dia vent in the door?

110m3/hr meets the minimum spec but if there is a lot of moisture generation then this may not be enough, however as said in other posts if the problem is continuous then look for other causes as well.
you only need a fairly small vent in the door for air flow, but it may also be worth looking at the likely air flow through the room if the door and fan are close together it may not clear the room.

 

[JB_]

Guy i used to work with, said he had this problem in his bathroom until he fitted a heater in there. Turns it on for a few minutes after showering to dry the moist air up

Yep, best way to keep the moist air moving is to keep the room warm.

Need to check for obvious water leaks first but heating the room will def help.

I've installed underfloor heating in several mould infested places, works a treat every time. Gives you a bitta work too

 

[sparks1973]

maybe its just a case of grubby tennants.....you never know...they may have mould on em n all....

 

[Guitarist]

Guy i used to work with, said he had this problem in his bathroom until he fitted a heater in there. Turns it on for a few minutes after showering to dry the moist air up

I don't think this can be understated, as has already been said. Many properties I have been to have had problems with damp and mould due to inadequate heating.

 

[tesla09]

envirovent filterless fan are great
permantly on with humididty tracking

 

[Marvo]

The extraction rate is 110m3/hr, as I am aware the bathrooms have been well cleaned with bleach and the doors are left open after showering. The main problem is two teenage daughters! Will a more powerful extractor do any good? How about a 4in dia vent in the door?

I would be careful where the extraction rate figure comes from. Usually the manufacturers figure on the box is for the fan in free-air, I've seen fans without ducting that are 25% short of the stated air movement figures as soon as you clip the cover on. If there's a decent length of duct installed I would actually take a velocity measurement at the fan or the discharge louvre and work out the volume from that. I'm still thinking it's probably a combination of undersized fan, and maybe poor provision for make-up air.

I would also actually run the shower and see how much it mists, we had a mildew problem in one of our ensuite bathrooms that was caused by a badly designed shower head causing fine mist that left the whole room drenched.

 

[sparks1973]

how about an airbrick putting in at low level....then a centrefugal inline fan......a decent one mind....

 

[dean.diy]

Evening Mike the Sparky. I have some rentals on my books, agreed with all previous threads.
Private tenants are always struggling and cannot have the heat on/up.
Windows are never opened. You've got to do your best on extraction.

- - - Updated - - -

 

[mike the sparky]

Thanks for all your help. I will investigate further and advise the landlord.

 

[BroadReach]

I would be careful where the extraction rate figure comes from. Usually the manufacturers figure on the box is for the fan in free-air, I've seen fans without ducting that are 25% short of the stated air movement figures as soon as you clip the cover on. If there's a decent length of duct installed I would actually take a velocity measurement at the fan or the discharge louvre and work out the volume from that. I'm still thinking it's probably a combination of undersized fan, and maybe poor provision for make-up air.

What he said.

It is the actual extract that you are achieving that is the key not the fan rating. 10 air changes/hour minimum I would recommend. This fan , if acieving the stated extract rate is still only achieving 7 ac/hr. After ductwork losses and struggling for makeup air probably a lot less.

Also air movement should be considered. In this case all that is practical is to look at fan extract position in relation to the make up air from (I assume) the bottom of the door.

 

[Engineer54]

Yep is the fan big enough and how long is the duct if its 1.5m or longer then you need centrifugal over axial also the fans take air out of the room is there a vent for fresh air to come in or a vent in the door is some old houses you could get Top Cats wallet in the space under the door.

One last point and please dont tell me I am racist I do repairs in rental properties and some of the tenants from the Indian sub continent have a LOT of bother with damp as the seem to do a lot of steam cooking throughout the day plus they will not and I mean not open a window or switch a fan on as it is toooooo cold in this country and tooooo expensive for electricity I have tried to explain that it is a culture problem and that they need to let the property breathe but to no avial

As oldtimer has mentioned one of the main problems with ducted extracts, is the length of duct the fan is expected push the humid air through. Add a couple or more bends, especially any tight'ish bends and your problems are magnified no end!!!

 

[tesla09]

try insulating all ductwork stops moisture from cooling