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Hi Team,
i have an issue with my decking area, the metal ceiling drips with condensation on winter mornings.
It is a single metal sheeted roof panels with battons.
How can i resolve this issue permanently and be able to put nice things out.
what insulation would you recommend and also ways to install this?
thank you
Welcome to the Bunnings Workshop community @bowmatty. It's sensational to have you join us, and many thanks for your question about insulating a roof.
That's pretty typical for metal ceilings, and I have a similar issue with mine.
Here are some similar discussions that you might like to check out:
The issue is really two-fold and has to do with how cold the roof is getting and the contact with air that's full of moisture. It would be best to insulate the seal and then clad over the insulation. Insulation panels would be easier to install than batts, as you can cut them to size and wedge/sandwich them between timbers. You'll need to install additional purlins that you can screw your roof cladding into before you start with the insulation. There will be different installation techniques involved depending on the type you select. I'd be happy to provide more information once you decide.
By insulating and cladding, you'll stop the underside of the sheets from getting as cold and exclude the moisture-laden air from reaching it. The added bonus of insulating is that it will help reduce radiant heat in summer.
Please let me know if you have any questions.
Mitchell
Thanks Michell.
Yep I’ve looked at the links you provided and have taken down some ideas.
Option 1: Textured paint the whole underside including the beams. Dont know how affective that will be when finished.
Option 2: Take off the whole roof sheeting and then lay sarking. This is the product im thinking to use- Ametalin 1350mm x 22.25m ThermalBreak Roof and Wall Home Insulation. Once sarking has been covered i will then relay the sheets.
Option 3: Between the underside beams ill measure and cut foil board product ill use- Foilboard 10mm x 2400mm x 1200mm Standard 10 Insulation. Which ill attach the Purlin Brackets for adding the cladding later. I wouldn’t have to take the sheeting off for this right? I have attached a picture of my design thought.
My preferred choice would be option 3 if i don’t have to remove metal sheeting.
Also, i have noticed the condensation only drips from the beams, causing drip lines under the beams onto the floor in the morning. Don’t know if this is just the sheeting trickling down onto beams and then dripping off the beams onto the floor.
please let me know your thoughts on the options?
many thanks
My preference would also be option three, @bowmatty. You won't need to take the sheeting off for this, but you might need to screw through the sheeting in places to fix the additional purlins/batons in place.
Textured paint might work, as it shouldn't allow the moisture to run and bead into larger droplets before falling off. I was going to mention sarking, but I'm not entirely convinced that it wouldn't also suffer the same effect as the sheeting.
I suspect the water is running down the sheets, hitting the purlins/beams and dripping off them. As it's running down the sheets, it picks up additional water particles on the surface and forms larger droplets. That's why you're getting such distinctive drip lines under the beams. If you get out there early morning with a torch, you'd likely be able to check if there are run lines down the sheets to the beams.
Let me mention a couple of our knowledgeable members, @Dave-1 and @MrSober, to see if they have any thoughts.
Please let me know if you have further questions.
Mitchell
It's certainly going to add a buffer and prevent the moisture-laden air from coming in contact with the cold sheeting @bowmatty. Plaster sheeting over the foil board will add an additional layer of protection. The main issue here is the metal roof sheeting temperature versus the surrounding air. When the air hits the dew point, moisture droplets occur on the surfaces that it comes in contact with. Cold steel sheeting is typically more susceptible to this than other mediums.
Mitchell
Morning @bowmatty
Sorry had a flexi yesterday and was stripping old paint off a doorframe. I dont have a lot of ideas about how to fix the condensation but here are a few thoughts.
If there is any air gap between the underside of the sheeting and the tin would condenstaion form?
If you put up insulation and then sheeting to cover it all will the existing trusses you have support it?
Would it be cheaper or possible to install channels on the underside of the trusses/ribs to catch the condensation? As in a small U shapped chanel?
If you take the option 3 with the foilboard foam I hope you post some pics 
Dave
If there is any air gap between the underside of the sheeting and the tin would condenstaion form? - This is a question i don't know, do i need spacers in-between?
Im happy to just install the insulation at the moment, once satisfied with the condensation issue i will consider cladding over.
Yep, will provide pictures once the job is complete
The condensation is formed by moisture-laden air coming in contact with the roof sheeting @bowmatty. If you exclude the air from reaching the sheeting, it can not deposit moisture onto it. By adding the foam board and taping to seal, no air can access the underside of the sheeting. Due to this, I don't believe having a gap between the foam boards and roof sheeting will matter, though the manufacturer encourages you to do so to improve the insulating values of the product. The air gap stops heat/cold from transferring from the sheeting to the foil board and radiating it on the underside.
It appears you've listed everything you need. Perhaps a couple of tubes of polyurethane adhesive would be useful if you need to glue the board to the roof in difficult-to-fix locations.
Mitchell
