Condensation on flat roof without insulation

[Sef1928172]

I am debating on whether to remove incorrectly installed insulation from unventilated flat cold roof.

Would condensation still form on the inside of an unventilated cold roof that does not have insulation?

I would assume the inside roof will still be the coldest part of the room so will condense when warm air hits it?

Thanks in advance.

 

[noseall]

Would condensation still form on the inside of an unventilated cold roof that does not have insulation?

Yes. It will form on the underside of the deck and the roof joists.

 

[Sef1928172]

Thanks for the response.

If that is the case , I'm questioning if I bother removing the insulation at all given that condensation will still form if I removed and left uninsulated. The only difference is I would be able to visually monitor the situation.


For context, this is a study, and I plan to change to a warm deck next year. There is currently insulation between joists with a gap between the insulation and cold deck (no ventilation though). The joists a taped with a foil tape and then there is a vapour control and then plasterboard.

No actual visibly signs on the ceiling of condensation or damp coming through but have a lingering concern about the condensation/mould levels behind all of those layers

Thanks

 

[datarebal]

Vcl not working well then

 

[Sef1928172]

Not sure I follow. Why do you say the vcl is not working?

 

[Deluks]

The title of your post suggests that there is condensation forming.
Or are you assuming condensation because of the lack of ventilation?

You might not have any, but hard to see without removing the ceiling.

If the vapour barrier and insulation is continuous and working, then you could retrofit vents externally to ventilate the roof, a much cheaper option. Circular soffit vents or roof mushrooms could be the answer.

 

[Sef1928172]

sorry if misleading title.

My situation is that I had a cold deck flat roof with no ventilation but it does have insulation between the joists with a gap between insulation and cold deck ( I realise now that this gap is pointless, as no ventillation).

I was concerned about condensation forming internally between the insulation and cold deck, (though there was no visual evidence on the ceiling that I could see) so was considering pulling down the plasterboard and removing insulation.

But even if taking down the insulation, the internal cold deck would still potentially be the coldest surface (dew point?) so condensation would form there regardless of taking down insulation or leaving as is, so should I save the effort

Sorry if longwinded respond. I am possibly overthinking things.

All responses much appreciated.

 

[Deluks]

If you remove the insulation, then your heat will go through the roof, as will your heating bill.

If you are changing it next year then not worth worrying about, if you can retrofit ventilation then do so.