Browse Forums Heating, Cooling & Insulation 1 Jul 20, 2010 12:58 pm Hello to all I have recently purchased my first house in Pennant Hills, Sydney. Its a late 60's/early 70's brick veneer, single level, cement tile roof, no sarking, no additional roof venting, Spray in type (paper mulch) insulation in ceiling void, ducted air-conditioning (not used much). Bathroom (and ensuite) vent/fan into ceiling cavity. Now the problem. I stuck my head up in the ceiling cavity on the weekend (chasing rats) to find everything was damp. Ceiling joists are damp/cold to touch, condensation can we seen on underside of concrete roof tiles. Not good. The question I have to everybody is where should I start first? a) duct bathroom vents externally? b) install roof venting/ fans (whirly birds, solar fans etc) c) checking for roof damage, broken tiles etc. d) what have I missed? By the pure volume of water up there, and its SPREAD all over the roof, I'm leaning towards a condensation problem over a roof damage problem. Has anybody else had a similar problem. Winter nights are not really cold in Sydney, 5-7 degrees, days are 15-17 degrees. Any help or comments wanted. Thanks in advance Bluey Re: Heavy condensation in non-sarking concrete tile roof. 2Jul 21, 2010 6:18 pm I'd try installing some roof ventilation to start off with and see what difference it makes. Most roof spaces have natural gaps allowing some ventilation but maybe yours doesn't. If the roof was leaking you would expect to see localised dampness patches on the ceiling. Re: Heavy condensation in non-sarking concrete tile roof. 4Jul 22, 2010 2:02 am Although night temps are not that cold, the concrete tiles are radiating heat into the cold night sky (which can have very low radiant temperature). This is cooling the tiles below the dew point. A moisture barrier beneath the tiles will catch the condensation and run it towards the gutters. Re: Heavy condensation in non-sarking concrete tile roof. 5Jul 22, 2010 9:06 am Hi Bluey I am in no way knowledgeable or an expert in this, but I do think that the roof needs all the help in getting the air moved around as much as possible. I personally would do all the things that I can do on my own first. So ... I would install some eaves vents (eg. drill holes) and make sure they are not covered by the insulation fluff. I would also definitely stop the vents/fans in Bathroom (and ensuite) from going into into ceiling cavity. Do your bathrooms have windows? If yes, maybe you can simply stop using these 2 fans temporarily (and use the windows instead) until the situation improves (maybe you'll need to block the ceiling vents too, just in case). And I would also install not less than 2 w. birds (there are also some fancy in-tile roof vents). After doing one or more of these simpler measures, I would re-evaluate if anything has improved. If not, maybe need to call in a 'doctor'. My signature is distracting people from my wise posts ... Re: Heavy condensation in non-sarking concrete tile roof. 6Jul 22, 2010 11:33 am Putting in vents in the eaves and whirlys aren't going to solve your condensation problem. In fact it will probably worsen the situation. All you will be doing is continually bringing in fresh moisture laden air to condense on your roof tiles. There is water vapour even within the outside air. Your problem is that the air is allowed to contact an even colder surface such that it reaches its dew point. In fact the better solution is not allow any new air to enter the roof space at all and place your moisture barrier under the roof tiles to catch the drips to be carried away. Similarly if you insulate the ceiling then moisture won't condense on a cold ceiling surface. Bulk insulation works better if it doesn't get wet so it is a win-win. We constructed our house this way and the everything is nice and dry in our ceiling space. BTW the contribution of moisture of vented wet areas doesn't contribute that much (maybe only if you had clothes dryer). Could you really imagine that your shower steam could saturate an entire roof space? Re: Heavy condensation in non-sarking concrete tile roof. 7Feb 18, 2011 9:12 am I can solve the Problem with the Western Soalr Roof Ventilator which is a soalr Powered Fan unit which is censor controled so that during winter when U need the warmthe from in the roof space the unit will not turn on unnecessarilly, & as for the comment re Vents in Eaves roof only draw moist air into the roof space rthis is not the problem it is the fact that the Wind driven Roof Vents are NOT CONSTANT enough and so do not do the same job of maintaining the correct Air Flow to maintain a dry roof / Ceiling Space & yes U need to change the rubbish Paper Insulation & install Fibre Glass / Polyester Insulation, Rgards Robsimbo Firstly, if your house is still under builder's warranty (10 years in Victoria) you should have no need to crawl into roof space but let the builder handle it, unless you… 3 5675 Building Standards; Getting It Right! Hi all Iām in VIC and had some storm damage in my garage a month ago. 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