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Elias Yoder
  • 6 hours ago
Water running down your windows may be a sign of excess moisture indoors—not faulty glass. In this practical home-maintenance guide, Elias Yoder explains how condensation forms, why colder rooms make damp more visible, and how everyday sources such as breathing, cooking, showers, and indoor laundry add moisture to the air.

Learn how to read the warning signs, from wet window frames and mold behind furniture to a single unusually damp room. The advice covers ventilation, drying clothes, moving furniture from cold walls, and keeping unused rooms from becoming cold and stagnant. This home damp and condensation guide offers straightforward ways to reduce indoor humidity, prevent mold, and understand when a failed double-glazed window seal is the real problem. Useful for anyone searching for winter condensation fixes, window moisture causes, damp prevention, or practical energy-conscious home advice.
Transcript
00:00You came down this morning, and the windows were running with water.
00:03Not misted. Running.
00:06A line of it pooled along the bottom of the frame,
00:09and there is a towel living on that sill now,
00:12because you got tired of the paint going soft.
00:15And you have decided the windows are the problem.
00:18Old windows, bad windows, somebody should come and look at the windows.
00:23I want to save you that money, because it is almost never the windows.
00:29A window is simply the coldest thing in that room.
00:32It is a thin sheet with winter on the other side of it,
00:36and everything around it is wall with insulation in it.
00:39So when the air in your house has to put its water down somewhere,
00:43it puts it down there first, because that is the coldest surface it can find.
00:49Your window is not making water.
00:52Your window is where the water shows.
00:55I am Elias Yoder, and this house has single panes and stone walls,
01:00and no heating system in it at all, so I have been reading windows my whole life.
01:06My grandfather taught me this one, and he taught it the way he taught everything,
01:11which was by refusing to answer a question.
01:14I was wiping a window one winter morning,
01:17and he asked me where I thought that water had come from.
01:20I said, outside, rain, or the weather.
01:24He said, no, that is your own breath, and your mother's, and the kettle, and the washing on the rack.
01:32You are not looking at the weather, you are looking at last night.
01:38Cold does not make damp.
01:41Cold makes the damp show.
01:44I gathered the whole of it into a book at EliasYoder.com.
01:49The book is the long version.
01:51If you want it, it is there.
01:53I will not mention it again.
01:56And I have to say something before I go on,
01:59because I am part of why a lot of you are seeing more of this than you used to.
02:03I have spent a long while on this channel telling you how to use less heat.
02:10Drafts, foil, bubble wrap, a cold bedroom done properly, a blanket underneath you.
02:17Every word of that holds, and I would say all of it again.
02:21But there is a second half to it that I have not given you, and this is it.
02:27When you lower the temperature in a house, you do not change how much water is in the air.
02:32You only change how much the air can carry.
02:36A cold room holds less.
02:39So the same water that was invisible to you in October has to come out of the air and land
02:45somewhere,
02:46and it lands on whatever is coldest, and in most houses, that is glass.
02:52And it is not a small effect.
02:55Take a room down a few degrees, and you have not removed one drop of water from it.
03:00You have simply lowered the point at which that water stops being invisible.
03:06Nothing came in.
03:07Nothing changed except where it chooses to land.
03:11Which is why so many people this year are convinced their house has suddenly developed a fault.
03:18The house has not changed.
03:20The house is doing exactly what it always did.
03:23You moved the line.
03:25Nobody told you that when they told you to turn it down, and I did not tell you either.
03:31So here is the whole of it.
03:33First, where the water is actually coming from, because people are always shocked by this.
03:40Every person in the house puts out something like a couple of pints a day just by living.
03:46Breathing.
03:47Perspiring.
03:48Sitting still.
03:49A family of four is a gallon of water a day before anybody has boiled a kettle.
03:55Cooking adds to it, and a pan at a rolling boil with no lid on it is pouring water into
04:01your house by the pint.
04:03A shower or a bath is several more, which is why the bathroom is the one room everybody already understands.
04:11And then the big one, which almost nobody counts.
04:15Drying laundry indoors.
04:18A single load of wet washing hung on a rack is a couple of liters of water, and it does
04:24not vanish.
04:25It goes into the air of your house, and then it comes out again on your windows that night.
04:30If you have a drying rack in a bedroom with the door shut, you have built yourself a machine for
04:36making damp.
04:37A tumble dryer that is not vented outside does the same, only faster, and one that catches people badly.
04:45A heater that burns fuel in the room with no flue.
04:49A paraffin heater, or a bottled gas one, makes water as it burns.
04:54Roughly as much water as fuel.
04:57So the cheap heater bought to fix a cold room is quietly filling that room with moisture,
05:03and a lot of people are solving a cold room and making a wet one in the same week.
05:09Two more that hide.
05:11A bathroom fan that has been run up into the loft, instead of out through the wall or the roof,
05:17is not removing anything.
05:19It is taking every shower you have ever had, and putting it into the coldest space in your building,
05:26and the damage that does up there is slow and expensive, and completely invisible, until somebody goes and looks.
05:34And a wet cellar, or a bare earth crawl space underneath you,
05:39is feeding moisture up into the house every day of the year.
05:43We have a whole video on what causes a damp cellar wall, and I will leave that one there.
05:49But if your downstairs is the wet part of your house, go and look below it before you blame the
05:56air up here.
05:58Now, how to read what your house is showing you, because the pattern tells you a great deal.
06:04Water on the glass only, and it clears by the middle of the morning.
06:09That is the mild end.
06:11Your house is a little wetter than it should be, and the air needs somewhere to go.
06:17And compare your windows against each other, rather than worrying about any one of them.
06:22The north side of a house gets no sun on it all winter,
06:26so those panes stay coldest, longest, and they will always be the worst in the house.
06:32That is normal, and it is not a fault.
06:35What matters is whether a window that should be fine is behaving like a north one,
06:41because that tells you that room has a problem the others do not.
06:47Water on the frame and running onto the sill and sitting there.
06:51That is worse, and it is the one that rots timber frames and lifts paint,
06:57and the water is not the enemy, the sitting is.
07:02Black spots in a corner, or behind a wardrobe, or on the wall behind a sofa,
07:08pushed up against an outside wall.
07:10That is surface mold, and here is the part people do not know.
07:15Mold does not need a puddle.
07:18It only needs a surface that is damp enough, often enough,
07:22and a cold corner with no air moving over it gets there easily.
07:28That is why it turns up in the exact places you cannot see.
07:33Clothes in a wardrobe on an outside wall going musty or spotted.
07:38Same thing.
07:40A packed wardrobe against a cold wall has no air in it at all.
07:46One room much worse than all the others.
07:49That room is your cold room,
07:52and the reason is usually either that you stopped heating it,
07:55or that it is over something unheated.
07:58And a tide mark low down on a wall,
08:02a stain a foot or two up with a line across the top of it,
08:06is not this at all.
08:08That is a different problem coming up out of the ground,
08:11and it wants a different man.
08:15Now, what to do, in the order I would do it?
08:19One. Make less of it.
08:22This is free, and it is the half everybody skips.
08:27Lids on pans.
08:28The extractor on when you cook,
08:31and left running a few minutes after you finish.
08:33The bathroom door shut while somebody showers,
08:37and the window open or the fan on afterwards,
08:41not during only.
08:43And the laundry, which is the big one.
08:46Outside if you possibly can, even in winter,
08:50because a cold, dry, windy day
08:52will dry a line of washing beautifully.
08:56If it has to come inside, put it in one room,
09:00shut the door on that room,
09:02and open that window a crack.
09:05One wet room with an open window is manageable.
09:08Wet washing distributed through the whole house is not.
09:142. Get rid of what you do make,
09:17and do it on purpose, every day.
09:20This is where the old rule comes in,
09:23and we have a whole video on it,
09:24so I will not go through the whole thing again.
09:27Short version.
09:29Twice a day,
09:30open windows properly wide for a few minutes,
09:34and let the air swap over,
09:36then shut them.
09:37Brief and vigorous beats a window on the latch all day,
09:42because a few minutes of real exchange
09:44carries the moisture out without time to chill the walls,
09:48and a window cracked for eight hours
09:51cools the structure,
09:53and costs you far more heat for far less air.
09:57And the timing matters more than the amount.
09:59Do it in the morning once everybody is up,
10:02because a house full of sleeping people
10:04is a house full of breath,
10:05and the air in those bedrooms is at its wettest
10:09the moment the beds are empty.
10:11Do it again after cooking,
10:13and after anybody showers.
10:15Those are the three moments the water goes in,
10:18so those are the three moments to put it back out.
10:21And if you only ever manage the morning one,
10:24you will still be most of the way there.
10:273. Keep the cold surfaces from being quite so cold,
10:32because the water lands on the coldest thing available,
10:35and you can change what that is.
10:37Pull furniture four inches off outside walls,
10:41so air can move behind it.
10:43Do not cram a wardrobe solid.
10:46Open the curtains in the daytime,
10:48because a closed curtain traps the window behind it
10:51in a cold pocket,
10:53and makes the glass colder,
10:55not warmer.
10:55And go and look at your loft hatch while you are thinking about cold spots.
11:00On a great many houses,
11:02it is a thin board in a hole with no seal around it and nothing on top,
11:08which makes it one of the coldest surfaces on the ceiling,
11:11and a straight path for warm, wet air to go up into the roof.
11:16A strip of draft seal round the frame,
11:19and a piece of insulation laid on top of the board,
11:22costs very little,
11:23and fixes a problem most people have never once looked at.
11:294. And here is the mistake I most want to warn you about,
11:33because it is being made in a great many houses this month.
11:37Do not shut up a spare room,
11:40and stop heating it altogether.
11:42I know exactly why people do it.
11:45There is nobody in there,
11:47so why pay?
11:48But that room is now the coldest surface in the whole house,
11:52and the air in your house moves,
11:55and it will find that room,
11:57and put its water down in there,
11:59where nobody is looking.
12:01People shut a room in November,
12:03and open it in March,
12:05to find the outside wall black,
12:07and the mattress spotted.
12:09If you are not using a room,
12:11leave a little heat in it,
12:13and leave the door open a crack,
12:15so the air is not stagnant.
12:18A little warmth in a room you are not using,
12:21is cheaper than redecorating it.
12:245. Wipe the windows,
12:27but understand what you are doing.
12:29Wiping is not a fix,
12:31it is damage control,
12:33and it is worth doing,
12:35because standing water on a timber frame,
12:37or a plaster reveal,
12:39is what turns a nuisance into a repair.
12:43Wipe it,
12:44wring the cloth out somewhere else,
12:46and then go and deal with the cause.
12:496. On the black spots.
12:52Clean them off,
12:53and then understand that cleaning is the easy half.
12:577. A spray kills what is on the surface,
13:00and does nothing at all about why that surface is wet,
13:04so it comes back,
13:05and most people conclude they need a stronger spray.
13:098. They do not.
13:119. They need that corner to be warmer,
13:13or drier,
13:14or to have air moving over it.
13:1710. And I will say plainly,
13:19that if somebody in your house
13:20has trouble with their breathing,
13:2210. Damp and mold in the house
13:25is not just a decorating matter,
13:28and that is a conversation to have with a doctor
13:31rather than with me.
13:33Now, the one case where none of this is your fault,
13:36and nothing you do,
13:38will help.
13:39If the water is between the panes
13:42of a double-glazed window,
13:43inside the sealed unit
13:45where you cannot reach it,
13:47the seal on that unit has failed.
13:50That is not condensation in your room,
13:53and it is not a habit you can change.
13:56That unit is finished and wants replacing,
14:00and no amount of airing or wiping
14:03or lids on pans will touch it.
14:06So before you blame yourself,
14:08go and look at which side of the glass
14:11the water is on.
14:13Outside the glass in the morning,
14:15by the way,
14:16is a good sign,
14:17and not a bad one.
14:19That means the pain
14:20is keeping your heat in well enough
14:23to be colder than the air outside it.
14:26Now, who gains from the way this gets handled?
14:30Go into any shop
14:32and look at the shelf for this problem.
14:35Sprays to kill mold.
14:37Tubs of crystals that sit in a corner
14:40and collect a thimble full of water.
14:43Dehumidifiers,
14:44which do genuinely work
14:46and which also cost money to buy
14:49and money to run
14:50every day,
14:52forever.
14:53Every one of those
14:55is sold against the symptom.
14:57Not one of them is sold against the cause,
15:00and the cause is a lid,
15:02a window opened properly for four minutes,
15:05and a drying rack moved into one room
15:08instead of three.
15:09I will be fair about the dehumidifier,
15:11because it is the one on that shelf
15:14that genuinely works.
15:16If you have a real problem
15:18or a room you cannot ventilate properly,
15:21it will pull water out of the air
15:23and it will do it reliably.
15:25What it will not do
15:27is stop the water arriving,
15:29so you are paying to run a machine
15:32every day
15:33against a thing a habit
15:34would have handled for nothing.
15:37Use one to get on top of a bad room,
15:39by all means.
15:40Just do not let it become the reason
15:43you never fix why that room is wet.
15:46Nobody is defrauding anybody.
15:48There is simply no product in a lid.
15:51There is no subscription
15:53to opening a window.
15:55So the whole aisle is arranged
15:57around the black spot
15:58rather than the wet air,
16:00and a person who walks in
16:02with a damp problem
16:03walks out with a bottle
16:05and the problem comes back
16:07in a fortnight.
16:08That is worse than a conspiracy,
16:10because a conspiracy can be exposed.
16:13It is just that only one half of this
16:16has anything to sell.
16:17And here is what I find striking
16:20about the whole business.
16:21Old houses did not have this
16:24the way modern ones do,
16:25and it was not because the old builders
16:28were cleverer about moisture.
16:30It was because those houses leaked.
16:33Air went in and out through the boards
16:36and round the sashes
16:37and up the chimney all day and all night,
16:40and every bit of water the household made
16:43went out with it,
16:45and nobody had to think about it once.
16:48Then we sealed houses up,
16:50which was the right thing to do,
16:52and saved an enormous amount of fuel.
16:54But the drafts had been doing
16:56a second job
16:58that nobody had ever noticed,
17:00because nobody notices a job
17:02that is being done for them.
17:04And when we stopped the drafts,
17:06we stopped the second job as well,
17:08and we did not replace it with anything,
17:11and we did not tell anybody
17:13it needed replacing.
17:15So now a house has to be ventilated
17:17deliberately by a person,
17:19on purpose,
17:21because the building
17:22will not do it for you anymore.
17:24That is the whole of what changed.
17:27It is the same story
17:29as nearly everything on this channel.
17:31We removed something that looked useless,
17:33and it turned out to be carrying a load.
17:37And that is why the old people
17:39never had to be taught any of this,
17:41and why we do.
17:43Their houses were doing it for them,
17:45whether they understood it or not.
17:47And a thing that happens by itself
17:49does not need to be passed down.
17:52So nothing was passed down.
17:55There is no piece of grandmother's wisdom
17:57about ventilating a sealed house,
18:00because grandmother never lived in one.
18:03Which means,
18:04this is one of the very few things
18:06on this channel
18:07where the old way is not the answer.
18:10The old way was a drafty house,
18:13and none of us wants to go back
18:14to paying to heat the sky.
18:16What we have to do instead
18:19is a new job,
18:20made necessary by a good change,
18:23and nobody has ever sat anybody down
18:26and explained that the job exists.
18:29Cold does not make damp.
18:32Cold makes the damp show.
18:35So tomorrow morning,
18:36before you wipe anything,
18:38go round the house and look.
18:40Every window,
18:42every room,
18:43and the corners behind the furniture
18:45on your outside walls.
18:47You are not looking for water.
18:49You are looking for which room is worst,
18:52because that room is where the answer is.
18:55Then come down to the comments
18:57and tell me which one it was
18:59and what is in it,
19:01because I would like to see
19:02how many of you
19:03find the same room
19:05I expect you to find.
19:06And tell me whether you dry
19:08your washing indoors.
19:10Just yes or no.
19:12I have a strong suspicion
19:14about how those two answers
19:16are going to line up,
19:18and I would like to find out in public
19:20whether I am right.
19:22Next time,
19:23I want to go through
19:23the first hour of a power cut
19:25in order,
19:26because there are two or three things
19:28worth doing in the first 60 minutes
19:30that almost nobody thinks of
19:33until it is far too late to do them.
19:36Thank you for sitting with me.
19:38Go and find the worst room.
19:40The people who built this country
19:42with their hands knew that,
19:44and we are only just starting
19:46to remember it.

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