What's the minimum temperature I should keep my house at to prevent damp?

[Belephant]

I've tried google, perhaps I'm typing in the wrong things but I can't find an answer.

As the title states really - I'm anticipating needing to keep the central heating use to an absolute minimum this winter. But I don't want to cause any damp issues in our house - it's an Edwardian end of terrace. It's all recently been renovated, so I don't fancy causing any issues right now!

So does anyone know what minimum temperature I need to keep my thermostat at to avoid damp issues please?

My house insurance says to keep my house at 16 degrees. But i have seen councils and charities suggesting 18.

They say a lower constant temp is better than short bursts.
Also air the house every morning.
You arent supposed to dry washing inside either but im not quite sure what you are supposed to do instead.

Damp isn't to do with the heat of the room or house, it's to do with the moisture in the air. You can have it very hot but if the air contains water it will promote the growth of mold.

I've heard 17/18 too.
I'm end of terrace and the wind and rain howls at the side of my house. The heating has to stay on or else I'll have a bigger problem.

you could get a dehumidifier if you're concerned about damp, especially if you dry washing indoors. They're much cheaper to run than a heater, although they are an upfront investment.

Yes to a decent dehumidifier, also blows out warm air.

An energy efficient dehumidifier would both remove the excess moisture likely to cause damp and also make the house more cost effective to heat.

Dehumidifiers are where it’s at.

My house rarely gets UP to 18 in the winter but it's very breathable (listed former church) so at least it isn't damp. Air circulation is what you're after, to stop damp, rather than a certain temperature. Pull heavy furniture away from the walls, leave a gap for air to get through floorboards and make sure your air bricks aren't clogged.

Ventilation. As a pp said even hot, humid air will cause problems. Cold and dry air isn’t an issue to buildings.

Brilliant thanks so much everyone - I will definitely look into a dehumidifier then!

The max I ever put my heating on anyway is 17 degrees, but in my cold draughty house that means the heating is on quite a lot! So I'll be banjaxed if I can't keep it any lower than that this winter with the rise in bills 😬

I didn't know that was a thing, does it apply to all houses? I can't think how my house would end up damp even if I never put the heating on, how does that happen?

I think that your breath condenses on the cold surfaces of the walls and windows makes them wet giving mould a chance to grow rather than the moisture just floating in the air - like a dew point.

Thats why ventilation is important

Temperatures on thermostats aren't really a reliable indicator, they aren't always accurate and if they are they are only accurate for the room they are located in. Get yourself a thermometer instead.

You need to make sure you are ventilating the house well to avoid damp and mould. The temperature that damp becomes a risk depends upon the moisture in the air. I wouldn't go below 16, but a dehumidifier would help avoid damp.

@JesusMaryAndJosephAndTheWeeDon I have one of those little digital thermometer things (cheaper than a gro egg!) that has a humidity reading on too, and I've put it in the same room as the thermostat and they have the same temperature reading, so I'm hoping that means it's not too inaccurate.

I'm thinking I can use the humidity reading to see how things are going and try and aim for 40-50%?

dehumidifer needs electricity to run & presumably OP wants to keep heating low to save money... not sure dehumidifier is right solution.

We get most damp in bedrooms, people breathing out wet air

You also need to identify the sources of damp and rectify them otherwise you will be throwing money away.

You might want to check other rooms too, most houses the temperature varies in certain rooms. If your thermostat is in a naturally cold room then other rooms will be warmer than the thermostat, it if is in a warmer room the rest of the house could be colder.

It does require electricity but generally running a dehumidifier is cheaper than a heater and the OP is worried about damp if she turns the heating down.

As other have said humidity is the issue. Humidity above 75% constantly and no ventilation will potentially cause issues .
you can get a humidity meter relatively cheaply and use that to check on humidity levels.

avoid stuff like hanging washing to dry inside and open windows after baths and showers or when cooking.

unless your house has a propensity to mould due to poor insulation (And mould normally forms on outside walls first or furniture up against outside walls ) or a leak, keeping the humidity down to 75% will avoid it

Hmmm. so a dehumidifier costs £40-£300
2015 price to run one 24 hours was £2.50-£6.50.
I guess lekki prices are projected 3x higher in 2022-23, so that suggests £7-£18/day.
But suppose you only ran it 12 hours/day, £3.50-£9/day, or £105-£270/month.

Since my back of envelope calcs must be wrong, what are the correct back of envelope calcs.

It's just that the warmer temps would make occupants happier too, not just dehumidify.

What means your house is losing so much heat OP?

I have a Victorian end of terrace, it's single skinned no wall insulation with double glazing and absolute max 4 inches of loft insulation. The extension I'm pretty sure has no insulation at all and you can see the outside world round the back door if it's not carefully bolted. I still only need to heat the house for about 3-4 hours a day to 18 for it to be comfortable.

So I guess what I'm wondering is is there anything you can do to reduce the heat loss, because it taking a lot of heating to keep at 17 sounds really hard work.

Another vote for dehumidifier.
reduces the moisture, makes it more efficient to heat and as a bonus puts out heat and kills viruses.

Or you could take the NZ approach (or at least common in Nz, there are some softies) and not heat your house. Often under 10 degrees inside in my siblings’ houses in the morning in winter. They’re a hardy lot, and the kids just wear enormous sort of hoodie blanket things to keep warm in the mornings and evenings. I’ve lived in the UK for years but still can’t get over the luxury of central heating .

You cant simply say that a temperature of xy will keep the damp out. It depends on how damp your house is and where the damp comes from. You need to get the air circulating to keep the damp out, ie open your windows.

You should first avoid creating condensation in the house.
Boil saucepans with the lid on, use the kitchen extractor fan. Avoid drying damp washing inside.
Use bathroom extractors or adequately ventilate and wipe down or squeegee tiles.
Damp is caused mainly by condensation forming on cold wall areas, especially corners. Good air circulation will avoid this.
Maintain the air temp above the dew point to avoid condensation forming, usually above 16'C ( it varies with the relative humidity)

www.eco-home-essentials.co.uk/dew-point-definition.html

Also from moisture travelling (rising damp) up the walls if no damp proof course is fitted. Normally older houses have raised floors and air bricks to allow ventilation under the floors and to evaporate moisture before the skirting board level.
Check your air bricks are unblocked allow good circulation. Also check gutters are unblocked and leak free and soil levels around external walls are below the internal floor level.