The Building Experience DIY Forum > concrete ceiling and condensation issues
the best way to do this is to stop the moisture-laden warm air touching the concrete. this can be done by ventilation, but this needs to be installed to create a cross flow of air at ceiling height. not easy in a concrete building. or you need a vapour barrier. this needs to be on the warm side of the insulation (ie below the insulation) and can be either polythene sheeting (use visqueen dpm) or foil backed plasterboard. this stops the water vapour hitting the cold air. if you have already battened and insulated the ceiling, you could pin a vapour barrier below. it would be very cheap. one more thing, the roof defo isnt leaking is it? you might be looking at the wrong problem!
regards
December 27, 2009 |
Tarquin
Tarquin
hi all
i am using an outhouse ( small singled walled building built onto our house ) as an office. Due to it having a concrete roof , floor and single walls i thought i would need insulation so i sealed the walls with aquaseal and then batoned and added 30mm phonelic foam insulation boards. I also added this to the ceiling but as you guessed there is a small gap between the boards and ceiling so i am getting condensation forming and dripping onto the boards and coming through the seams. i thought if i remove the boards and add some loft insulation to the boards so there no gap between the ceiling and boards this will cure the issue as the warm air will not be able to touch the concrete ceiling as there will be loft insulation sand wiched between. will this work. i need it to end as my computers dont need the moisture dripping down onto them. i also leave the window open and have a dehumidifier running which gets a lot of water but still not enough. so will adding the loft insulation ( rockwool) idea work ?? is there anything else i can do ??
thanks in advance
i have removed one of the phonelic foam insulation boards today and the ceiling is very wet so i have to do this in the next couple of days, so if you think this will solve the issue i shall bang on with it but if it will not work i need to know before i actually do it.