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Tiled floor causing mould and mildew on walls?


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Good afternoon, 

This is my first time posting a question here so please forgive any mistakes?


We bought our house about a year ago (UK) and the whole downstairs is tiled with ceramic floor tiles(poorly laid cracking around doorways). 


The walls are always extremely cold to touch and so is the floor, we have just moved the storage boxes from under the stairs to find the exterior wall covered in mould all along the skirting and on and in the storage boxes. 


We are wondering what is causing the mould? Is it a symptom of the heating being on and causing condensation on the cold walls and floor? 


We are going to replace the flooring with laminate next year, any things to look for and do to prevent the mould returning? 


Thanks for looking 

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I doubt mould on the walls is being caused by the choice of flooring.


I take it, this is an old house?  Care to describe it?  and what EPC rating did it get from the selling agent?


Sadly a huge amount of the UK housing stock is very poorly built and in particular very poorly insulated.  The only solutions are to improve the insulation, or to just pump lots of heat into them and keep them very well ventilated.

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My house was notorious for mould but changing the way we live and installing a positive input ventilation system At the top of the stairs as well as extractors in bathroom and kitchen with long overrun times had cured the problem, I use minimal During the summer and only purely necessary heating in the winter because there is no insulation and it would cost to much........ 

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7 hours ago, Mr Punter said:

The cause of the mildew and mould is warmer moist air condensing on the cold surfaces quicker than it evaporates.


You may find a dehumidifier could help.


We once had a house that had a room over a porch. The bit of floor over the porch was less well insulated and colder. We had so much condensation on the floor it formed puddles overnight. Pointing a desk fan at the floor was enough to warm the floor a bit and increase evaporation to the point where they stopped forming.

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I think a dehumidifier is going to be your best option here, dessicant ones from Meaco also give out heat as a waste product, which is useful in winter, and you can leave them on 24/7 as they will come on and off as needed based on the RH setting. Be warned though, they aren't cheap to run, but you will likely draw many litres of water out of the air, and fabric of the building which will help greatly.


This will of course only mask the problem, you then need to come to a consensus as to what the problem actually is (poor insulation, rising damp, penetrating damp) and work on a more permanent fix.

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Various solutions would work, for sure .. to deal with the symptom or various possible causes. 


Get yourself a couple of Min/Max Humidistat/Thermometers at £10 each - I use these:



That will tell you how low and high both are going. Humidity should be 50-60%. If that is consistently high, then you are having to heat up all the extra moisture in the air as well.


We can't zero in on cause without more info - insulation, draughtiness, type of glazing etc.


Dehumidifier would help extract moisture from the air. As would a PIV fan y improving ventilation - I recommend Nuaire ones which would be bought and self-fitted from about £300 (example). I have these in all houses I renovate, and have seen them stop moisture which appears on window sills next to single glazing throughout a house within days. There may still be other underlying causes to fix to make the house work better.


If you want to whack it on the head quickly, then I would say consider those two ideas.



Edited by Ferdinand
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