Is it possible for vacant properties to reach an equilibrium in dampness around the house?

[Michael55]

I've been looking at a 1920/30s house, both from photos of summer 2023, july 2024 and a recent viewing and the many damp stains on the walls around the house don't seem to have increase in size during the time. There is some black mold there (perhaps not as much as I'd expect considering how long it's been vacant) but also many different colour molds growths that looked exciting! There is a musty smell generally all around the house which is making me concerned for the woodwork as it's a fairly sizeable place.

Is is possible for the damp patches to settle down, or maybe be periodic? Throughout the day, weeks or months? Is this an indicator of the areas that will always have damp, or be very likely to have it? Of course, the damp patches were in the gloomy parts of the house so maybe putting up mirrors to bounce around the light may help there?

 

[aockenden]

Sry mirrors won't solve any damp problems. Yes there are definitely macro-fluctuations in house condition through the change in seasons. Internal humidity, amount of moisture in the walls due to driving rain, water-table level changes, etc.

 

[Michael55]

But wouldn't mirrors help to get more light to currently gloomy areas?

 

[a twig]

Why would light help with damp?

 

[Michael55]

OK< I was thinking maybe it'd help warm it up

 

[a twig]

Radiator would be more effective

 

[stuart45]

The problem with damp walls is that they are colder than dry ones, so they are more likely to attract condensation, which makes them even damper and colder.

 

[Stevers]

Our stone house had been empty for eighteen months when we viewed it, and although the roof was watertight(ish) damp was building up in the fabric to the extent that wallpaper was falling off the walls and even the internal shutters on the front windows were giving alarming damp readings. The single glazed windows were draughty enough for a sensible number of air changes, but that seemed to just introduce more damp air to condense on the cold walls that then seemed to get colder. All those problems went away when we introduced central heating and targetted ventilation. However before we had smart heating and we used to put off turning the heating on in the Autumn, a sort of clamminess used to descend on the house and you realised how necesssary a bit of heat is to the health of these old buildings.

Fitting smart controls to our existing gas central heating (from 1997) has been by far the best investment we've made when it comes to saving money and increasing comfort.

 

[Michael55]

Fitting smart controls to our existing gas central heating (from 1997) has been by far the best investment we've made when it comes to saving money and increasing comfort.

Interesting - is this per rad or the whole system?

 

[Stevers]

Interesting - is this per rad or the whole system?

Each rad has it's own schedule of times and temperatures and the warmth follows my mother (and us) round the house during the day, no temperatures in any room at any time ever drop below 13C and that helps with condensation. We can properly heat my son's office/bedroom upstairs during the day, and my mothers bedroom downstairs at night. Because of the extra warmth needed for my mother (94) we are exploiting the extra efficiency to not use any more gas than before. Eventually we'll be able to reduce the temperatures and our gas usage.

We are single glazed, but we do have 20" stone walls that are basically dry with many internal voids, the house is a cube, none of the rooms have more than two external walls and nearly all the radiators are on internal walls, so the house is efficient in ways that no EPC will ever give us credit for.

 

[malcolm]

I bought my house after it had sat empty for over a year. They had boarded up the windows and left a lot of ventilation so whenever suddenly got warmer outside all the air would come inside and condense on the colder walls. I didn't have a lot of mould though. That's normally water condensing on an impermeable surface that is cold so the water can't soak into the wall before the mould gets a chance to grow.

Heating is very helpful. Photos would be useful.

 

[CliffordPope]

Why would light help with damp?

Because light is an energy beam, and patches where light shines are warmer than unlit. Ask any cat!

 

[a twig]

Because light is an energy beam, and patches where light shines are warmer than unlit. Ask any cat!

Sure, direct sunlight has a significant infra-red spectrum which provides the “heat” part.

Once you start bouncing sunlight off mirrors (which generally are only designed to reflect visible light rather than the IR spectrum as well) you’re into rapidly diminishing returns, hence my comment about putting in a dedicated heat source like a radiator instead.

 

[jamest]

Glass is a very poor transmitter of infra red. Longer wavelength IR is almost completely reflected and absorbed by the glass, only some of the shorter wavelength IR passes through. Luckily for greenhouse owners, visible light will heat up absorbent (i.e., dark) surfaces inside the greenhouse and the glass will prevent any heat re-admitted as IR from getting out.

 

[a twig]

This is why the cool kids use polycarbonate or acrylic for greenhouses these days

I re-roofed my parents greenhouse in polycarbonate last summer and inside it’s a cross between a rainforest and day of the triffids in there now!

30 degrees and 80% humidity, never seen tomatoes and courgettes that big before!

 

[CliffordPope]

Sure, direct sunlight has a significant infra-red spectrum which provides the “heat” part.

Once you start bouncing sunlight off mirrors (which generally are only designed to reflect visible light rather than the IR spectrum as well) you’re into rapidly diminishing returns, hence my comment about putting in a dedicated heat source like a radiator instead.

Archimedes was said to have burned a Roman fleet by reflecting sunlight on to the ships. The exploit has been successfully demonstrated on a more limited scale since. Certainly house fires have been caused by careless positioning of glass objects.
We are only talking here about a slight warming. It's easily enough to cause me to sit in the morning room in a pool of sunlight to eat my elevenses.

Of course, the patch of light moves round with the sun, but the warming effect of sunlight is surely undeniable.