Condensation on walls

[foxhole]

Ventilation isn't the only answer, as otherwise, there would be no dew on spiderwebs outside ....

Trickle vents might reduce the problem though.

Please explain, dew condenses on the spider web because it's cold then evapourates during the day as it warms or get more air across it.

 

[JP_]

why does it get more air during the day? It is less windy at night?

water evaporates all the time - a puddle, or dew on a web, will evaporate so long as it is not freezing. More condensation will form so long as the temperature is below the dew point. Ventilation helps speed up evaporation, but does not stop more condensation forming. Heat is needed for that.

Both condensation and evaporation happen together at the same time, but the environment determines which one wins.

I'm not saying the ventilation does not help, it does. But that is not the only solution. Without warmth, condensation will still form quicker than evaporation can remove it, which is why dew forms outside even on breezy nights.

 

[JP_]

More heat allows more moisture to be held in the air, .

Exactly - moisture remains in the air, not condensing on cold surfaces.

Explain this:

I've had the pleasure of drinking ice cold beer on beaches in Brazil, where there's a strong wind blowing off the Atlantic. Condensation always forms, because, in spite of the huge amount of ventilation, the glass is cold so condensation occurs at a faster rate than evaporation. When the glass warms up, and the beer becomes undrinkable, condensation disappears.

OK, if you have loads of ventilation in a room at night you will significantly reduce condensation as you will be pushing that water vapour away from the wet surface faster, but, your room will be freezing.

Wack up the temperature and reduce cold surfaces with insulation, and hey presto, you don't need to ventilate at all.

I guess the only question really is, do you want to live in a windy cave or a cosy room?

 

[foxhole]

Exactly - moisture remains in the air, not condensing on cold surfaces.

Explain this:
View attachment 154386

I've had the pleasure of drinking ice cold beer on beaches in Brazil, where there's a strong wind blowing off the Atlantic. Condensation always forms, because, in spite of the huge amount of ventilation, the glass is cold so condensation occurs at a faster rate than evaporation. When the glass warms up, and the beer becomes undrinkable, condensation disappears.

OK, if you have loads of ventilation in a room at night you will significantly reduce condensation as you will be pushing that water vapour away from the wet surface faster, but, your room will be freezing.

Wack up the temperature and reduce cold surfaces with insulation, and hey presto, you don't need to ventilate at all.

I guess the only question really is, do you want to live in a windy cave or a cosy room?

You got it backwards, you cannot warm your walls to beyond dew point unless you spend a fortune on heating, the hot air does not retain the moisture it condensers on any cool surface, your glass is an example, high humidity and cold surface = condensation.
OP does not have option of insulation.

 

[foxhole]

Wack up the temperature and reduce cold surfaces with insulation, and hey presto, you don't need to ventilate at all.

Building regs would disagree, all homes have to have ventilation.

 

[JP_]

that's what I said, when I said "Keep it warm all the time, and no condensation (but massive energy bills)"

 

[foxhole]

that's what I said, when I said "Keep it warm all the time, and no condensation (but massive energy bills)"

Interesting theory, keep home sealed tight, no ventilation , no kitchen fan, no bathroom fan, dry your washing indoors and all will be fine if its hot enough.

 

[JP_]

Obviously ventilate the bathroom and kitchen - I thought the suggestions was more ventilation in all rooms.
Anyway ... even with loads of ventilation, you will still draw moist air into the house which if cold, will condense...

Old houses have drafts. Old houses get damp and mouldy. We could go on all day.

 

[EFLImpudence]

I am with Durhamplumber on this one.

Ventilation - that is removing the moist air as soon as it is produced - is the only answer APART FROM making less moisture in the first place.

If you have lots of people, animals, plants, washing drying, lots of cooking with boiling water you will make lots of moisture.


Empty unoccupied houses do not have condensation problems.

 

[foxhole]

Obviously ventilate the bathroom and kitchen - I thought the suggestions was more ventilation in all rooms.
Anyway ... even with loads of ventilation, you will still draw moist air into the house which if cold, will condense...

Old houses have drafts. Old houses get damp and mouldy. We could go on all day.

You can lead a horse to water etc etc.

 

[empip]

This guy reviews a de-humidifier - some 3 yrs ago.

He used to make quite a decent video for an amateur.

Never overdo dehumidification, over time it will dry out timber etc. Possibly a good solution if managed sensibly.
-0-

 

[JP_]

I have one a similar size, works a treat. Not needed so much now that I've insulated most of the walls.