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Hi
My name is Merin , can anyone give suggestions how to stop the condensation under colour bond sheet
thanks
Welcome to the Bunnings Workshop community @Merinjorly. It's wonderful to have you join us, and many thanks for your question about preventing condensation under Colorbond.
We have had plenty of previous discussions in the community about condensation forming under Colourbond patio roofs, and it is unfortunately something that happens naturally whenever the steel sheet temperature, the surrounding air temperature, and the moisture in the air all meet at the right point. That combination creates dew point, which leads to moisture forming on the underside of the roof and, in many cases, dripping down. On a standard flat roof you can usually manage this by installing insulation directly under the sheeting, but that becomes more challenging with a curved roof like yours.
It would help to know a little more about what you are hoping to solve, because the approach will differ depending on whether you are mainly trying to stop mould and mildew forming under the sheets or whether you are dealing with water dripping onto people below. Regular cleaning with a mould and mildew spray does help slow regrowth, and soaking the underside then rinsing with a pressure washer is an easy way to get the existing buildup off. Remember to wear PPE including safety glasses, gloves, a long-sleeved shirt, trousers and enclosed footwear.
How long does it usually take for the underside of your roof to get to this state? If it is building up quickly, insulation is the long term fix, although with a curved structure it is more involved and may require additional framing to support it properly.
Please let me know if you have any questions.
Mitchell
Early morning dew dripping from the underside of a Colourbond roof is quite normal @Merinjorly, although water dripping during rain is less expected. That makes me wonder whether some of what you are seeing during rain might actually be a leak through screw penetrations or another point in the sheeting rather than condensation alone, so it would be worth checking those areas carefully before you go ahead with painting.
When you mention painting the roof, I am assuming you mean the underside. Painting alone will not stop condensation because it forms from the temperature difference between the steel and the air, but you can definitely reduce mould by treating the surface with a pre-paint mould cleaner first, then mixing a mould-preventative additive into your paint. That will help slow future growth. After that, the best way to keep it under control is periodic cleaning with a pressure washer, because once mould takes hold it can spread quickly.
Mitchell
