Mist on windows in mornings and evenings... Causes loads of mold, cant stop it!!

ColinFishwick

I only get a very small amount on coldest of days but I run a dehumidifier and humidity in house varies from 35% to 60% at most ideally around 40%-50% is best

DRP

I'd get a couple of cheap meters off amazon to test %RH.

If it started 5 years ago suddenly, could be water ingress somewhere? Our house used to have a high humidity issue down to a damp subfloor - up to 80% or so in the worst areas. Fixed the issue (touch wood)and niw were at 40-55%RH fairly constantly.

pollypenny

We have the bedroom window open slightly. I addition, we have a couple of those cheap desiccants on each side of the sill.

OH puts out loads of heat!

TheCyclingProgrammer

Those dessicants won't do anything. Get a cheap hydrometer and take some measurements around the house. You need to know what levels you're dealing with first. Chances are a decent dehumidifier will be a good solution. They normally have clothes drying modes too so you can safely dry clothes indoors over winter.

Grenage

Stop drying clothes indoors, or get a dehumidifier; tumble dryers are a better choice imho.
Fit a bathroom extractor if you don't have one installed.

oystercatcher

My parents had a similar problem and long story cut short it was eventually discovered to be leaking pipes under concrete floors.

Major upheaval !

So as suggested start with damp meter.

alejamruc

Hi, we live in a victorian terrace with double glazing and used to have the same problem. Have now solved it entirely for about £400. Here's what we've learnt in our search for a solution:

It happens over night more than during the day because 1) our bodies give off a fair amount of moisture while we sleep, so more moisture in the air over night 2) the outside temperature is lower when it is dark, so colder external walls/windows, meaning moisture will condense on them more easily

More moisture + colder walls/window = condensation

The only solutions are to:
- Increase the temperature of those surfaces where condensation is forming
- Reduce the moisture you create
- Get the moisture out of your house once it is created

Getting the external surfaces of your house to a constantly higher temperature isn't easy. Especially if you have an older property (ours has solid brick walls) then heat leaches through constantly. Double glazing is much better than single, but heat still escapes. Heat your house reasonably so your walls/windows are not ice cold all day and night, but turning up the heating is never a complete fix in my experience, and it's a costly solution over time.

Reducing the moisture is more easily said that done. We live modern lives, with showers, cooking etc. Yes, drying washing outside is sensible, but in winter it isn't viable, and condensing tumble dryers are fairly expensive to both buy and run. Do the best you can, but realistically you're going to create a load of moisture through normal living.

Getting moisture out is therefore the best and most cost-effective in my opinion. However, we increasingly seal up our houses to keep in heat, but this in turn keeps in moisture. Opening windows more is the low-tech solution, but you'll lose a lot of heat. Extractor fans are a must, but they don't vent your whole house and their effects are more localised. Dehumidifiers will again help, but they are a pain to always have on, and again their effects are quite localised.

After lots of research (and frustration at trying everything else), we installed a positive pressure ventilation system (also called a positive input ventilation system). We opted for the Nuaire Drimaster Eco Heat model.

It was below zero the day after installation. Normally we would have water pooling on the window sill, but the windows didn't have a spot of mist on them. Also, our bathroom has two exposed walls so the walls would be dripping in water after a long bath. Now, we leave the door open during a bath, put the unit on 'boost' and there are no issues (the most we get is a light steam on the window, but we don't even get a steamed up mirror now). Black mould issues on external walls behind furniture are also completely gone. We also continue to dry washing inside with no problems (in fact, towels on the banister under the vent dry noticeably faster, as does a clothes horse of washing!)

We have put it through its paces in an old house in the depths of winter with people who like to have long hot baths, and I am genuinely astonished by the results. After a few months I am now making a point of getting on some forums to make these things more widely know, as black mould has always been such a battle in every property we've ever lived in and I know it is for so many people.

Damp companies charge around £800-1,000 to supply and install these units, but any vaguely competent DIYer can honestly do it themselves (so long as you have an existing plug socket or light-fitting near where you put the unit). For the Nuaire one we bought, I even found a step-by-step video installation guide on YouTube. We spent about £400 on the unit and I installed it within a couple of hours.

If you do get one, the hallways control unit is a good buy, as you can boost the fan speed for baths/showers etc. As air takes the path of least resistance, you can also get clever at channeling the flow where you want it, by closing doors and opening others (so, during/after a bath or shower we close all other doors expect the bathroom door + turn on the extractor - it then directs the flow there and clears out all of the moisture really quickly).

Just to make clear, I have absolutely no links to any manufacturers/damp companies etc.. I am however searching for threads on condensation/black mould to hopefully make more people aware of this as a solution to something that has pained us and so many friends/family for years.

Really hope this info helps sort your problem