Will Kingspan *above* joists create condensation below the Kingspan?

Discussion in 'Eco Talk' started by Willferox, Apr 5, 2022.

  1. Willferox

    Willferox New Member

    The loftspace above my kitchen is cold/ventillated. As a result, the kitchen is very cold. There is currently loose rockwool there. I'm considering adding 100-150mm solid insulation above the rafters so that I can better insulate the ceiling and also lay loft-flooring on top, for light storage.

    The kitchen inevitably produces lots of moisture. I have searched the internet for this question but not had much luck: If I insulate above the rafters with foil-backed solid insulation, will I create an environment in which moisture gets trapped directly below the insulation, around the rafters? Essentially, could this create a dam/rot problem?

    I'm reluctant to insulate between the rafters because the rafters are only 75mm deep, a bit wonky, and I don't want to cut the insulation board to size.

    Thank you in advance.

  2. ElecCEng

    ElecCEng Screwfix Select

    Yes you will create an environment prone to condensation. Is that a problem? Not necessarily. Adequate ventilation in your kitchen and a barrier above the plasterboard will eliminate most of it. Make sure your cooker hood vents outside and you have an additional extractor. Then you’ll need trickle vents to replace the moist air you’re extracting.


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