Dampness On Walls

[Ric.ror]

I have noticed in the spare room dampness in the corner of the room
It cannot be condensation as the room always has the window open and it also has the radiator on too
What can it be?
I have also noticed damp around the window - not near the damp on the walls

[KARL]

Unless you have somehow sprayed the walls with water then it has to be condensation - on the window it is also condensation. The cause might be poor insulation, although if the heating is intermittent (i.e. timed) then that might be the cause because then these areas never actually warm up in order to stay dry as opposed to cooling the air in contact with them and causing dumping of moisture (condensation).

[granny grump]

I'm having a similar problem. The damp is on the front room wall. we have been in the house for more than 25 years and this problem started about 15 months ago. It is at floor level and at the corner of the window and front door. I have a feeling that it could be the pointing. It was done by the son of our neighbour about 2-3 years ago. we don't have damp any where else in the house, With the recent heavy rain the front of the house really takes a battering

[KARL]

granny grump, I regard it as highly unlikely that pointing has anything to do with your dampness. As the pointing presumably was needing renewed, any water (rain) hitting the outside of the house would have got even further before it was renewed so you would have had worse problems.......

[granny grump]

Any idea what else it could be Karl?

[Ric.ror]

Thanks for your replies already but perhaps I should add that the room is empty apart from some clothes rails and I never use the room. Also the door to the room is always left wide open so I can see straight through
If it was condensation where is it coming from?

[sandyRoe]

Could it be from the kitchen , steam from cooking and the kettle? When it comes to a cold surface near the window it condenses?

[Ric.ror]

I doubt it Sandy - it's on the front of the house and the kitchen is at the back
Furthermore I should add that apart from sleeping in the house I am rarely there - dividing times between my work, mothers and sons

[Mosaic]

Every house has its coldest point, and this is where damp mouldy patches may occur. So first of all, is the corner of the room away from warmth / radiator etc? If so, try running a heat source in the room for a while - with the window ajar - and see if that has any effect.
It might be a faulty gutter/ rainwater downspout, overflowing or cracked - stand outside and have a good old stare at it, see what you notice.
Are the windows double glazed / relatively recently installed (ie not 1970s aluminium) - if so, get back to the installers for a chat - if they are older windows it may be that their time is approaching....again, a good inspection of the sealing around the outside of the window frame can't harm.
And it might be just this wonderful weather we're having.

[KARL]

Ric and granny grump, condensation needs certain conditions in order to occur and these conditions are more often present in the UK than in many/most European countries. Possibly the biggest factor is that the day to day atmosphere in the UK is more humid than is known in lots of other places. Also significant are levels of insulation, heating and ventilation but there are others.

Atmospheric air always contains water and the warmer it is, the more it is capable of absorbing/holding. When air cools down far enough you get to the point (called dew point) where the air is about to become saturated, that is it is "full to the brim" - cool it just a tiny bit from there and the moisture literally gets dumped, onto any surface or (in the open) it will condense (e.g. fog, clouds, etc.) and ultimately fall under gravity (rain).

UK housing stock has until recently been notoriously badly built when it comes to heat retention (and in one or two other ways besides) and traditionally there has in fact been a reliance on deliberate draughts (windows constantly open, vents that are constantly open to the outdoors, etc.) in order to continually replace the air within structures in the hope that if it is at dew point then what comes from outside will perhaps be a bit above that.

The problem with this is that if/when people want to be warmer than outdoors they heat the place - the warmer air sucks up available moisture from all around, textiles, walls, furniture, the air we exhale, etc., etc. However, if for any reason it subsequently cools down then it will inexorably slide toward dew point. The areas where it drops to dew point first will be at windows, cold areas of walls and floors (typically behind furniture against the wall and curtains, corners, anywhere that circulation is not as rapid as elsewhere) - the closed bathroom while bathing/showering effect is the most dramatic when the entire place can be seen running with water.

But, these examples are far more often seen in the UK than elsewhere and while climate is one reason, user habits are just as important. I don't know anywhere else where, among people who can well afford it, heating is as low on the priority list as in the UK. For example, I have not seen a heating timer installed in a dwelling anywhere else than in the UK - people heat by thermostat to continuous (perhaps varied up and down within 24 hours) comfort levels day and night but never turn the heating off entirely. Intermittent heating will not heat up the fabric of a house to a sustained level and there will permanently be areas where there is a risk of condensation because the air floating to them is cooled down and sheds its moisture. All it needs is for the various contributing factors to line up in a way where it is inevitable - a lot of the time they won't but some of the time they will.

Except for some very unusual features of your homes, I am convinced condensation is your problem because otherwise the evidence would be very localised.

[Ric.ror]

The windows are double glazed and it is the box room so it's not the biggest room
I think I'll just strip and treat with bleach
That should do the trick - just don't know where it's from

[jomifl]

You get dampness around windows because the shortest path between inside and outside is around the windows so it is easier for heat to escape and as a consequence it is colder.

[jomifl]

Get a humidity meter( they don't cost much) and check thr humidity in your house. Dehumidifiers aren't very expensive andcost little to run because the energy they use ends up as a heat source in the house. Additionally you win a little free heat from condensing water vapour.

[The Builder]

Excellent post from Karl, as always. I would put money on condensation. The symptoms and the likely causes are all there.

What's the age of the house, Ric?
Bungalow? Terrace? etc etc?

[granny grump]

Thank you Karl for that very detailed answer - much appreciated

[Ric.ror]

It's a semi probably 1930's
I've lived here on my own for over one year and for 6 years in total.
The bedroom hasn't been slept in for 4 years

[The Builder]

Yep, condensation, Ric ... a 1930s semi ... bound to be. The insulation level in the exterior walls will be approx. zero ;o(

Blown cavity wall insulation would help a lot. The interior air temperature has to be raised. Another method ... something I've done many times, is to line the interior surfaces of the exterior walls with 50mm battens, with 50mm Celotex insulation between the battens. Then vapour check polythene, plasterboard and skim. Sockets can be brought forward and fitted into plasterboard boxes.

It may seem like a huge job, but honestly, very straightforward for a decent tradesman. The results will bring you much nearer to modern standards.

Older houses were fine when they had draughty windows, open fires, doors that didn't fit properly etc. They breathed out all condensation. Modern "air-tightness" negates all of that.

There's quite a lot involved in bringing older property in line with modern lifestyles. It's something that is often overlooked.

[Ric.ror]

Ok - well in the cold light of day it seems the dampness is all along the exterior wall - so I am going to strip, treat with bleach and then re-paper
As I intend having the whole property re-rendered early next year and then rent it out that should suffice - I hope