Damp Conservatory

[Peter James]

At the rear of my house I have a small conservatory. It covers about 15 square yards, and at the highest point of a sloping roof is approx 8 foot high. The walls are constructed of double glazed units and the roof is of plastic twin wall roofing sheets.

Mould and damp has become a problem in the conservatory that is most likely increased by our habit of hanging up wet coats after walking the dog during periods of rain.

I did wonder if the purchase of a small de-humidifier would control the damp/mould. I am aware that the hanging of wet clothes in such a structure is self defeating, but as it's off the sitting room it is easier that running wet clothes to the garage to hang them up. A dehumidifier would hopefully solve all of my problems, if it's viable. Pff

[Chris Hogg]

How long is a piece of string? Yes, a dehumidifier would reduce the humidity in there (it's what they do, after all!), but whether sufficient to prevent mould depends on several factors.

My first thought would be simply to provide a bit of ventilation - crack a window open, for example - and see if that solves the problem. You don't say in which direction the conservatory faces - N,S,E or W. If it's anything other than N it should get some sunshine on sunny days at any time of the year which will warm it up and reduce the humidity if you ventilate it. But without ventilation you just get more 'fug' that condenses on colder spots and in corners, and encourages mould.

I have a conservatory that faces SE, and routinely hang my laundry up on a rack in there. There is always a window cracked open. On really wet days, the laundry is dried off in a spare bedroom using a dehumidifier, but I never use one in the conservatory.

But there may be an issue of security. Access to my conservatory from inside the house is via what used to be a secure outside door, so anyone breaking in would also have to get through that door. And I have an intruder alarm in the house.

[Thomas Prufer]

Possibly something like this:

would help. Looks very DIY-able: a dark solar thermal collector, plus a small fan on a small PV panel would blow warm air into the conservatory when the sun shone. Depends on if there's enough sun for it to work... but it sounds as if just a bit of heat and air exchange might be enough.

Thomas Prufer

[Tricky Dicky]

The issue with conservatories and for that matter every room in the house is balancing the need to preserve heat whilst providing adequate ventilation which is not easy unless you have one of the ventilation systems that extracts the heat from the venting air and feeds it back into the house.

Your conservatory roof is probably the worst possible for preserving heat. When we moved into our bungalow the conservatory had a double glazed roof but in the evenings the temperature drop was quite marked compared to the rest of the house. We had the roof replaced with an insulated roof and the improvements were instant.

Coming back to the issue of ventilation we do not have trickle vents but keep all opening lights open on their night setting just a slight opening. This is something the previous owners seemed not to do judging from the black mould evident when we moved in. This has never been a problem since venting this way. We accept that we are losing heat but to us it is a price worth paying for comfort.

Our conservatory would not be allowed under present building regs. as it is an extension on one of our bedrooms with no doorway and the combined room has two radiators. We had a curtain with a thermal lining between the two parts but this was a faff. The biggest improvement we made was to use Hive with smart TRVs which overcame the problem of having a single room thermostat as each TRV can demand heat for the radiator/room it controls, you can literally heat a single room if required. We now have comfortable even heat throughout the house accepting that the conservatory portion loses more heat than any other room.

We had a dehumidifier for clothes drying purpose and it really sucked the moisture out of the atmosphere and made the conservatory markedly warmer. The only issue with them is that you have to prevent sucking in cold damp air from outside so they work best in an unventilated sealed room. Our daughter is making good use of it in her flat for clothes drying purposes.