Windows to solve condensation problem?

[stork]

We have a condensation problem which is becoming a mould problem.

The problem is worst around the bedroom and bathroom windows, where the glass can be very wet in the mornings. The window reveals also have condensation which develops into mould.

We are upgrading our bathroom extractor fan, which is feeble, but I suspect that this will not be the whole solution. We rarely dry washing indoors, and then generally in a utility room with the door closed and its own extractor fan. We run the cooker hood extractor when cooking, so we are doing what we can to avoid generating excessive moisture.

We are considering replacing the windows in the 4 affected rooms. They are currently uPVC frames, double glazed, 15-20 years old.

I believe that with more efficient (low-E) sealed units, we're less likely to get so much condensation on the glass, and that new frames might also be better insulated.

However, I'm not sure about the following:

-is it worth replacing frames, or just replacing sealed units?
-if replacing frames, should we get the plaster/sills stripped off and then insulate in the cavity (e.g. cavity closers) to try to avoid condensation in the window reveals?
-if the blockwork is 'returned' to the brickwork, how do we open up the cavity?
-will trickle vents help (better ventilation) or make things worse (colder glass)?

 

[JohnD]

if there is water vapour in the room, it will stay there until it either escapes, or finds a cold surface to condense on.

So start with ventilation, and be sure to get trickle vents in your windows.

As an experiment, open the windows every morning when you throw back the bedding, and leave them open until after breakfast. It is likely that this will both dry out that night's condensation, and leave the room drier for the following night.

 

[freddiemercurystwin]

Consider Positive Ventilation eg http://www.nuaire.co.uk/our-products/Residential/products?pt=1685 This is becoming very popular these days, in fact I have condensation myself (wife just will not open windows) and chap at work had same issue and has just fitted two (he has a big house) and is reporting good things so far but I shall wait a little before I invest. Certainly a helluva lot cheaper than new windows which will not help anyway.

 

[AronSearle]

We are considering replacing the windows in the 4 affected rooms. They are currently uPVC frames, double glazed, 15-20 years old.

I believe that with more efficient (low-E) sealed units, we're less likely to get so much condensation on the glass, and that new frames might also be better insulated.

It would be worth getting a surface temperature thermometer (you can get cheap IR thermometer of fleabay for about a tenner).

Then you can determine how cold the fame, window surround and glass is (though with the glass you have to be carefull where exactly the IR thermometer is taking a reading). Then you can determine whether it is worthwhile replacing the frames or just the glass.

Certainly worth seeing if you can rip of the reveals and stick some foam around the window. If the brick is returned, I don't know what you can do about that (I don't do brick). If the window surround is excessivly cold, and you can;t resolve this, then no point getting new windows as you won't solve the issue of condnesation at this point without leaving trickle vents open permanantly (which then negates the point of flash windows).

If any of the internal surfaces hit single figure temperatures, which can happen around poor or poorly fitted windows, then it will be very difficult to avoid condensation even with good levels of ventillation.

 

[JohnD]

leaving trickle vents open permanantly (which then negates the point of flash windows)

No it doesn't.

A trickle vent is not a vast amount of uncontrolled airflow.

If the tiny ventilators are constantly open providing a small amount of ventilation, they will keep the internal humidity down. A lot of the time there will be no significant heat loss (e.g. as I write the sun is shining and I have the bedroom windows open)

 

[AronSearle]

(e.g. as I write the sun is shining and I have the bedroom windows open)

Yea, so what?

I can sit in my office with single glazing and the window open, and it is warm when the sun shines.

Now try leaving your trickle vents open all night on a cold night, of course you lose heat, especially when it is windy.

 

[freddiemercurystwin]

You don’t lose a significant amount of heat through a trickle vent even when fully open all night long. They provide some background ventilation that is all.

It is accepted even by BC that Partl L and Part F clash in this way but there is no other cheap solution, if you want to minimise condensation you need to ventilate. It’s pretty simple.

 

[freddiemercurystwin]

@stork, do you have trickle vents in the windows?

 

[footprints]

As said the problem is moisture given off by sweating and exhaling moisture,
there are some extreme amounts quoted but around 400ml in your breath seems to be a reasonable figure you have to consider that some of what you exhale you will breathe in again, so it's almost impossible to be precise.

Just look at your breath on a cold day or the windows on your car when parked up and waiting in the car.

We always have a window open at night and leave it for about an hour after getting up that stops any condensation problem in the bedroom.

Quite interesting is we found in the morning we came down to the lounge to find on pulling the curtains back the windows suffered badly but opening the curtains and leaving the lounge and other doors open stops that too.

Don't waste money on changing upvc windows, the only time it's worth it is single glazed or the old aluminum ones.

 

[AronSearle]

if you want to minimise condensation you need to ventilate. It’s pretty simple.

Ventillation is one solution, or part of a solution.

It is not the only solution which is all anyone here seems to parrot.

Without knowing surface temperatures and humidity, it is all guesswork.

You don’t lose a significant amount of heat through a trickle vent even when fully open all night long. They provide some background ventilation that is all.

Depending on the window it can account for 30% of heat loss.

 

[freddiemercurystwin]

if you want to minimise condensation you need to ventilate. It’s pretty simple.

Ventillation is one solution, or part of a solution.

It is not the only solution which is all anyone here seems to parrot.

Without knowing surface temperatures and humidity, it is all guesswork.

You don’t lose a significant amount of heat through a trickle vent even when fully open all night long. They provide some background ventilation that is all.

Depending on the window it can account for 30% of heat loss.

Who said it was the only solution?

You can say it’s all guess work but my solution will be significantly easier, cheaper and far less disruptive than yours which is theoretical anyway, once the OP measures the surface temp of his windows how will that help him?

Fitting new windows will not solve it either, it will only make the problem worse if there is still inadequate ventilation, only providing even warmer surfaces for moist air to condense on.

Where does your 30% figure come from?

You are kidding yourself if you think a solution exists that does not in one way or another involve using more energy to ultimately remove the moisture from the air in some way.

 

[AronSearle]

You can say it’s all guess work but my solution will be significantly easier, cheaper and far less disruptive than yours which is theoretical anyway, once the OP measures the surface temp of his windows how will that help him?

It will help him decide if it is worth replacing the glazing only or also the frames, or if it is worth replacing any of them.

only providing even warmer surfaces for moist air to condense on.

Where does your 30% figure come from?

A paper I can't remember the origin of, possibly a BRE/Historic England research project.

 

[JohnD]

improving ventilation will always be be significantly easier, cheaper and far less disruptive

 

[ronniecabers]

Copied from another thread I posted in , which in turn was taken from a conservation website

Condensation 10 - "If you fit double glazing it will cure condensation"

Nothing could be further from the truth. Often before double glazing is fitted the single glazed windows 'steamed up' or ran with water on cold mornings. After fitting new double glazed windows hey presto the condensation no longer forms on the windows - in other words it is no longer visible but has it gone away?

Well from the windows yes - but previously the single glazed windows ran with water and in so doing they acted as a dehumidifier removing water vapour from the atmosphere within the property. It is also very probable that the old single glazed windows did not fit as well and they provided a certain amount of 'involuntary ventilation'. By fitting draft free sealed unit double glazed windows the dehumidification effect of the single glazed windows is removed and the 'involuntary ventilation' prevented.

If the life style of the occupants remains unchanged then a proportion of the water vapour that previously formed on the windows or escaped in draughts will very likely form elsewhere. It is not unusual for mould growth to form in corners on walls as a result of condensation after double glazing has been installed.

So does double glazing cure condensation? No it does not - it just shifts it elsewhere.

and a bit more info.....

Condensation 11 - "They say ventilation will cure condensation"

Water vapour exerts a pressure and areas of high vapour pressure (such as inside our homes) will always seek to equilibrate vapour pressure by moving to areas of lower vapour pressure (outside) and ventilation provides an 'easy' escape for this to happen. However not only does water vapour escape but also heat. The warm moist air is replaced by dryer cooler air which is good but some have suggested this reduces wall surface temperatures leaving them more susceptible to condensation. The cool replacement air also has to be heated to maintain comfort levels within the property and this costs money.
There is no doubt that controlled ventilation will contribute towards the reduction of a condensation problem and create a healthier environment but it probably will not be the complete cure. Other control measures are likely to be necessary and a complete cure lies with the life style activities of the occupants.

Hope this helps

 

[AronSearle]

improving ventilation will always be be significantly easier, cheaper and far less disruptive

Sigh.

Yes it is easy and cheap, but not necessarily good.

If surfaces are excessively cold, then you may need excessive levels of ventilation.

Fine if you are happy to live in cold draughty conditions or want to wastes loads of heating energy.

Some people want to move away from practices fit for 1960s standards.