To vent or to insulate?

[AvidDIYer]

I have a single brick ‘shed’ that has been integrated into the property as a little nook/larder opposite the kitchen. There’s a bigger shed directly behind, which seems to offer enough insulation for the back wall. However, there are two small sides that are exposed and the temperature difference creates condensation.

I’ve tried using thermal paint (it’s a bit small for insulation inside the nook), but it doesn’t seem to be enough to compensate.

I’d like to get some advice on whether it would be best to add a layer of insulation on the outside? Or, whether it would better to add ventilation (possibly even an extractor fan), and if so, would it be more beneficial to have the vent at the top or bottom?

I’ve literally joined mumsnet today because I haven’t been able to find anything helpful on the search engines 😕So please bear with me while I get the hang of it 😂

Appreciate any insight to help me make the decision (even if it’s something I haven’t mentioned). Many thanks

I think whoever integrated that into the house didn't comply with quite a few building regulations! What you have there is basically a conservatory/outdoor store.
The compliant solution would be to reinstate the external standard doors at the main house exit, which would also improve your heating bill as you'd lose less heat.

If you want to make the most of a bad situation I think external insulation would be the gold standard, but even looking at that "skylight" it looks like just some kind of plastic sheet rather than double glazed units etc? It would take a lot of work and compromise to get something compliant.
Another option would be a dehumidifier, which would cost to run but might be a short term option

Thanks for getting back to me. The picture may be misleading, I thought it may be helpful to show where it is but the part that looks like a skylight is a conservatory style exit from the kitchen. The white space inside is the part that gets the condensation. I appreciate the conservatory space would be colder than the rest of the house but in fairness, it looks to be well constructed and there are no drafts, so I believe it’s well sealed. (Also, the roof is double glazed btw ☺️)

I do have a dehumidifier in there currently and as you say, it’s more a short term solution and isn’t as effective as I would like.

With this updated information, would outside insulation still be your recommendation?

I really appreciate your help 😁

Another option would be to knock down and rebuild to building regs.

Yes. Agreed. Pull it down and start again.

External insulation would increase the internal wall temperature and hence reduce condensation as well as reducing your heating bills. You would then need to introduce ventilation if you have high levels of humidity.