Insulating a conservatory

[Thomzo]

Hi
Could any builderish type people give me some advice please? I have a fairly standard PVCu conservatory. It's south facing with one solid wall against the living room, another wall which is almost all made up of the French doors into the dining room. The third wall is double glazed PVCu windows and the last is a combination of the same windows and double glazed PVCu French doors into the garden. It has a dwarf wall on the two window sides and a polycarbonate roof.

I have the classic problem of it being too hot in summer and too cold in winter and it suffers badly from condensation. I'd love to use it as a craft studio but the temperature fluctuations and damp would stop me being able to store paper, paints, glues etc.

I will have to do something about the roof as it's starting to develop small holes through the outer layer of the polycarbonate. They don't leak yet....

It's the main source of light for the dining room so I don't want to sacrifice too much glass, although I could probably do without a third of the window wall (one window) as it only faces into a dark corner of a courtyard. Could I pop some insulation against the window and put some plasterboard on the inside face or would that cause damp problems?

I've had a quote for replacing the poly roof but would an alternative be significantly more thermally efficient?

Any advice would be very much appreciated.

Thanks

[Green Aura]

A picture would help, Z. I can't quite imagine it from your description.

As a temporary measure what about blinds?

We have thermal blackout blinds which we bought a couple of years ago. Since we knocked out the kitchen dining room walls we now have three windows and a door - all DG and only one double radiator. The first winter we noticed a marked drop in the overall temperature we were used to in the smaller living room. So we installed these on all the windows (including the one on the door) I can't tell you how much difference they make to our living room. Suffice it to say we've bought more this year to put in every other room.

For the roof, you can get triple thick polycarbonate, or even thicker, which may reduce light levels a tad but will up the thermal properties a lot.

As for the damp, unless you heat it in the winter and throw a window open for a while each day it will carry on being damp no matter how much you insulate it. Maybe concentrating on moisture-free storage for your craft supplies might be an idea.

[Odsox]

That's very interesting.
I have the same type of conservatory although mine has only one house wall with three walls of windows. It also has a triple walled polycarbonate roof, probably like yours.
Until this autumn it has been used as a "proper" conservatory, meaning it has always been full of plants and overfull with tomatoes during summer. It also had condensation from all that foliage and I had to have a dehumidifier in there to stop the tomatoes getting blight.
But for the last month it's been empty, of plants that is, as I have now handed it over to Mrs Odsox as a craft room and since then there has been no condensation at all. The hygrometer is still in there and pre-sunrise this morning it was 50% RH with an outside temperature of 7 degrees and the dehumidifier hasn't been used since the handover.

So do you perhaps have a damp problem?
When I built the conservatory I laid damp proof membrane under the concrete floor and also filled the sub-walls with polystyrene insulation.
I would look for obvious signs of damp, either from the floor or through the walls. Do the sub-walls have a cavity and if so could there be a damp spot where the wall ties have been bridged with mortar? If it's a single skin wall has it been rendered on the outside and if it has are there any cracks in it?
The condensation can only come from water vapour in the air and if there's no source of water in there, no amount of temperature swings will cause the windows to "steam" up. So find the source and you can then hopefully stop it.

[Odsox]

Just to prove it, a conservatory devoid of plants. What a waste.

conservatory.jpg (215.84 KiB) Viewed 16916 times

[Thomzo]

Thanks, both. There's no obvious sign of incoming damp so I suspect the plants are the main source of condensation. I don't want to get rid of all of them but I do have a dehumidifier which would help. putting some heating in would also help but I don't want to heat it until it has some insulation. Interesting about the triple wall poly. I'll have to investigate that one. If I get a chance at the weekend to take a photo, I will.

The blinds are also interesting. I wasn't sure if they'd make that much difference but, if they do, then they are a good option.

Thanks

[diggernotdreamer]

We have just built a garden room, doesn't have double glazed windows, but the walls are made of shiplap outside, kingspan insulation inside the cavity and then tounged and grooved wood inside. We have made the roof of 16mm triple polycarbonate sheets, they have been great, we have had snow and frost and no dripping at all, we get a little condensation on the windows in the morning if we have washing on the dryer, but it soon goes once we light the stove. The triple polycarbonate seems to keep it cooler in the hot weather, we did notice that it is several degrees cooler under our veranda than outside in the hot sun (we put a roof along the whole length of our house and part of it has been closed in the form the garden room).