Domestic mould in bathroom

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mike the sparky

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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
 

telectrix

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if you have an outside wall, bash a hole and fit a vent.
 
D

Dave 85

I'd always use a timer fan, switched with the lights over a humidistat. Never had much faith in them.
 
S

StuSpiers

what kind of building are we talking about?

If it is a concrete pre-fab which has been 'modernised' by that I mean central heating & double glazing then mould will appear.

Ventilation may not help that situation - having lived in a house with those problems I would recommend a bulldozer.
 

Richard Burns

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You may find that the extract ventilation is not enough if the rooms are not adequately heated, you would also need to know the extract ventilation rate achieved by the fan, the wattage is not a good guide to the rate of air flow.
As you seem to have persistent problems then a professional assessment of the ventilation, usage, and air flow may be needed.
Is there a gap in the entry door sufficient to allow the air to flow through the room or is the room sealed when closed?
 

needasparks

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You could check they are NOT leaving the door open during or after showering and make sure any airvent holes are covered up or moist air will not be removed as air takes the easiest route. The only place air should enter is under the door at the most.
 

Strima

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Sounds like the plaster/walls could be damp as well, would be an idea to probe them with a damp meter if you can lay your hands on one.

Problem with mould is, once it gets a hold there's no real easy way of getting rid of it short of knock all the plaster off and running a dehumidifier for a few weeks which is not ideal.
 

Murdoch

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What they need is a big bottle of bleach, a pair of decent rubber gloves and a mask - and then give every surface a good going over.

Don't mess with anything other than good old bleach!
 

Marvo

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Assuming a damp issue check for the obvious such as rising damp in walls or leaking plumbing in walls or above ceiling etc

You say there is a fan installed. The first 3 questions would be;

I the fan capable of moving between 10 and 12 times the volume of the bathroom per hour?
Is there a vent in the bathroom door for replacement air (make-up air) to enter?
Where is the fan discharging the humid air?
 
OP
M

mike the sparky

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wokingham berkshire
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?
 

ruston

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What they need is a big bottle of bleach, a pair of decent rubber gloves and a mask - and then give every surface a good going over.Don't mess with anything other than good old bleach!
Good old Domestos will shift it , but you need to get the air changes sorted as has been said ; and put the timer on max lol. Seriously though heat and air flow has to be considered, if it's a typical let the house could soaking with damp as has been suggested.Call manrose and give them the dimensions of the rooms an the will tell you the air flow you need.again.

To late again b/band dropped out
 

Mark_Burgess

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..........
Change the manrose for an airflow, xpelair or ventaxia.
Then fit Positive Input Ventilation (not into the bathroom directly), along with the bleach session should stop it from re-occuring.
 

oldtimer

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Edinburgh
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
 

diditrain

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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

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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_

EF Member
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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

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

Guitarist

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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.
 

Marvo

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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

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

dean.diy

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Brighton
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 - - -
 
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BroadReach

Regular EF Member
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49
Location
Sussex by the Sea
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.
 
E

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!!!
 

sparks1973

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Leeds
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!!!
yep...straight runs (where possible) for ducts.....you can have a max of two 45* bends for 100MM ducting...i think thats what it is anyway
 
J

jackpeterhen

I had gone through the post. Many equipments are available for cleaning the mould in bathroom,actually It is one of the severe problem for many of them, but there is a best solution is there. Generally. water a little bleach down & spray it, like our bathroom needs more ventilation. Please produce some more attachments about the topic for view detail information.
 
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