Ventilation (aka drafts) as a cure for condensation

[tobydog]

Unfortunately our listed 1640's part-timber framed thatched cottage was, like many others, a victim of a well meaning builder in the 80's. He still lives in the village (I know here he lives!!) and to a certain degree I do forgive him because the significant work he did do with all that cement and concrete was of a high quality!! Unfortunately it has left us with concrete floors, cement render, and gypsum boarding to all of the ceilings and some walls.

Despite the kitchen now being a new separate room only joined to the main house by a link (hallway), and a new fan in the bathroom that would give a Dyson a run for its money, we still get horrendous condensation during autumn, winter and spring. People talk about improving ventilation as a means of helping alleviate this, however, for us that just means opening a window. In the winter this is pretty much impossible because we have the larger side openings as opposed to the smaller windows at the top which you could leave cracked open. Our windows fit very tightly and, despite a chimney and a drafty front door, the windows are usually covered in heavy condensation every day during these months.

I am sure the concrete, cement and gypsum play a big part but these are not going to get changed anytime soon. Our oil bills are high enough already without leaving windows open 24/7 so does anyone have a magic cure? I've thought about getting a loft mounted air pump that brings fresh air in from the outside and, apparently, blows old air out through the gaps but these have mixed reviews and, I guess, blow nice warm air out as well.

I want to start doing work now on improving the insulation and drafts but logic suggests that fixing the drafts would no doubt make the problem worse.

Are we truly destined to a life of mopping up water, slowing rotting frames and having the cleanest windows in the country?

 

[Lime]

There is no magic solution to condensation problems.
Wherever warm moist air meets colder areas of the house condensation is likely to occur.
Ventilation is the easiest method to remove some of the moist warm air in the house and lower the humidity of what air is left by dilution with less-moist but colder outside air.

However if that is not possible then the moisture in the air needs to be reduced by other means.
Bathrooms and kitchens are usually the main source of water vapour in a house apart from humans themselves.
Often some rooms are much warmer than others.
If all interior doors are kept shut and are sealed so that air movement from one room to another is reduced condensation house-wide will be reduced too.
Try to ventilate particularly damp air rooms (after bath or shower, after cooking, after getting up) when not in use and keep the interior doors shut to keep the damp air in one room only.
Heat the house gentle all the time.
Remove furniture and other items away from walls where condensation occurs and use a simple fan (i.e. using no heat) in any room to keep the air circulating and prevent some condensation occurring.

 

[Penners]

It's questionable whether the cement and concrete in your house is contributing to the condensation. As lime has explained, condensation occurs when the warm, moist air in the house hits a cold surface. So the temperature of the surfaces is much more important than what those surfaces are made of.

Again as Lime mentioned, you need to reduce the moisture in the internal air as much as possible... or get rid of that air with ventilation. So you could install extractor fans in your dampest rooms and/or try using one or more dehumidifiers. Just don't dehumidify too enthusiastically, or you could start causing drying-out and cracking of structure and/or furniture. Gently does it.

The best solution of all is to take whatever steps you can to insulate your house. This would increase the temperature of the internal walls, thus reducing the precipitation of moisture from the internal air.

 

[chapel]

If it really is a problem then you could think about a heat recovery ventialtion system
it would take your damp/warm air out and replace it with drier/warm air (much more energy efficient as some magic goes on so that the air you expell is used to heat the air coming in)

 

[stuart45]

Having single glazed windows and a woman with a J cloth is a cheap form of dehumidifer.

 

[Penners]

Any man who lives with a woman will tell you that that suggestion is tantamount to perpetual motion.

The woman will always exhale moist air (through the larynx) faster than she could ever mop up the resulting condensation.

 

[tobydog]

Thanks for all the advice on the house and my domestic affairs! Unfortunately the input from my girlfriend (actually fiancee) only extends to drawing hearts in the condensation which of course leads to a torrent down the window.

We don't actually get condensation on the inside walls except for one corner. I thought, from all the scare stories, that the inside of the outside wall could be a problem. I dig hack off a small section of the gypsum plaster infill between the timbers and to be fair the top of the sole plate and the uprights I saw were in good condition. Certainly more than could be said about the bottom of the sole plate were the brick has disintegrated and left the sole plate (bottom side badly rotting) suspended in the air. This is due to the long term concrete encasement inside and out and will be the subject of another post.

I am seriously looking at the various pumps. We have only been in the house just over two years which have been the coldest on record so time will tell if we are forced down that route. I agree that the insulation will give a better overall warmth to the house and might help. I did look at adding trickle vents but these are unsightly and not, as I understand, particularly effective or well liked by CO's.

 

[MdB]

A little warning. If you insulate your walls, you will make the condensation on any uninsulated parts (i.e. your windows) worse. The insulation will make your house warmer will enable the air to hold more moisture. When it hits the windows, you will end up with more condensation. The solution is to secondary glaze your windows if possible / allowed.

 

[tobydog]

MdB - good point. It is a bit of a Catch 22 and finding the lesser of two evils. I have actually looked at secondary glazing and I'm considering the plastic ones that are temporarily connected to the window frame by a thin magnetic strip. I understand the CO's don't mind these so much because they are quite discreet when both on and off. My only concern was that they, apparently, still need some air movement between the window and the plastic. I'm thinking of trying two this year on the corner of the house that faces NE. If it works, and has no major side effects I will do the rest of the house next year. I think they work out about £100 per window. We only have nine windows in the old part of the house. The lounge is triple aspect and has four windows alone which does make it a difficult room to heat. The huge inglenook takes up one end of the room, two walls are about 9" brick and the front is timber frame with infill. Unfortunately the original wattle and daub is long gone. If anyone fancies a competition to see who has the most disproportional inglenook compared to the size of house then I'm up for it!!

 

[jocelyn plummer]

Did anyone watch DIY SOS last night-- the air circulation solution was interesting

 

[tobydog]

No I missed it. Out walking the dog before the sky fell in! Given that they are normally into more modern buildings, was it something that would lend itself to an older listed building?

 

[Penners]

Did anyone watch DIY SOS last night

I quote Jack Nicholson, in the film Terms of Endearment:

"I'd rather stick needles in my eyes."

 

[JoceAndChris]

Poor you, try to avoid drying laundry indoors. Lids on pans whilst cooking. Shower with open window. Use a dehumidifier gently.
Good luck - a few small changes can make a real difference.

 

[tobydog]

The annoying thing is that one of our neighbours have an old listed house very similar to ours and they don't get any condensation whatsoever. Come rain or shine, summer or winter. I think I will need to go and introduce myself.

We do have a condensing tumble drier that we used to use for the winter but I have to say I'm not convinced by them. It does collect water but the utility room is also normally running with water afterwards. We now have a new boiler room with a 35C + temperature thanks to the combi inner tank. We do hang the washing in there but we leave the extractor fan on while it dries.

I will try all the recommedations and report back later in the year.

 

[Penners]

We do have a condensing tumble drier that we used to use for the winter but I have to say I'm not convinced by them. It does collect water but the utility room is also normally running with water afterwards. We now have a new boiler room with a 35C + temperature thanks to the combi inner tank. We do hang the washing in there but we leave the extractor fan on while it dries.

Well, you have just identified two prime sources of condensation.

Condensing driers are - in my opinion - dreadful. They condense a modest amount of the water that comes out of the washing, but they pump large quantities of water vapour into the atmosphere. I urge you to get the thing vented and extracted to the exterior of the house as soon as possible.

When you dry washing indoors you don't release most of its water into the atmosphere - you release all of it. I trust that you have a very effective extractor in your boiler room, together with a generous source of airflow into the room (without which the extractor won't work properly).

Do these rooms - the drying room and the boiler room - have outside walls?

You really need to sort out both of those situations. I'm prepared to bet that, while they may not be the complete explanation for your condensation problem, they're a major part of it.

 

[CliffordPope]

Dehumidifier. Keep all doors and windows tightly shut. Ventilation will just let in more damp air to condense on your cold walls and windows.

 

[Lime]

The annoying thing is that one of our neighbours have an old listed house very similar to ours and they don't get any condensation whatsoever. Come rain or shine, summer or winter. I think I will need to go and introduce myself.

We do have a condensing tumble drier that we used to use for the winter but I have to say I'm not convinced by them. It does collect water but the utility room is also normally running with water afterwards. We now have a new boiler room with a 35C + temperature thanks to the combi inner tank. We do hang the washing in there but we leave the extractor fan on while it dries.

I will try all the recommedations and report back later in the year.

Condensation is all about lifestyle.
If you dry clothes indoors or refuse to open windows enough you WILL get condensation even in a brand new house.

 

[Flyfisher]

Dehumidifier. Keep all doors and windows tightly shut. Ventilation will just let in more damp air to condense on your cold walls and windows.

No fresh air? I don't like the sound of that.

I've read guidelines/regulations stating that room air should be changed seven times per hour, or four times per hour in bathrooms and kitchens, for a comfortable living environment.

 

[MdB]

Dehumidifier. Keep all doors and windows tightly shut. Ventilation will just let in more damp air to condense on your cold walls and windows.

Outside air is generally drier than outside air - even if it is raining. This is due to warm being able to hold a lot more moisture than cold air.

Condensation occurs when warm air gets cold and not when cold air gets warm.

 

[stuart45]

You will get condensation on any surface with a temperature at or below the dew point. You need to balance out the ventilation with the heating. BRE recommend one air change per hour for most living rooms for the average family. Kitchens and bathrooms require more when in use.