Condensation on my insulation

Discussion in 'Builders' Talk' started by Done Up North, Oct 29, 2019.

  1. Done Up North

    Done Up North New Member


    I'm trying to insulate a single skin concrete garage workshop as best I can without too much outlay as we rent. We've fixed up 50mm polystyrene sheets to insulate the metal corrugated roof (strung in place between the struts so there is a gap above them) and padded out the wooden double doors and 'double glazed' the window.

    I'm using an infra red heater to keep costs down on heating - temp is fairly low 15-16 but it works to keep me bodily warm without heating the air... (the humidity is staying below 70% which is what I need for painting...) but I think that might be contributing to the problem if the polystyrene is being warmed by the heater and the air is cooler?!

    My science might be backwards there but basically I'm getting drips forming on the underside of the new ceiling which are dropping onto things... assuming it's condensation because the garage is better insulated now with less ventilation... I can't really ventilate better as that then lets the cold in and the heater wouldn't be able to deal with that... I can try to use a dehumidifier though I think the air might be too cool with this heating method to actually work (it tends to need it to be 20 degrees ambient temp to actually do anything) Ideally I would prefer not to have to run another piece of eletrical equipment all day.

    We were thinking to fit a felt / fabric layer over the face of the Polystyrene to absorb the condensation which would hopefully then be heated by the infrared and dry out, rather than get dank and mouldy.

    Does this sound sensible or I am I going to find this is a waste of time? Any suggestions to deal with the drips would be great as they're dripping on my work...and me!

  2. JustPhil

    JustPhil Active Member

    You need a vapour barrier on the warm side of the insulation, and ventilation on the cold side of the insulation (between insulation and metal roof)

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