How to stop condensation on patio roof?

[condruss]

Hello. I’m after some advice. I have an outdoor metal patio with single sheet metal roof. We would like to enclose a section with a room and the other area with half colour bond and drop down screens. The problem we have is build up of condensation water droplets on roof underside. How can we stop this happening? What products could we use? The patio size is 10x3.5 on a concrete slab. Thanks Shane

[MitchellMc]

Welcome to the Bunnings Workshop community Shane (@condruss). It's sensational that you've joined us, and many thanks for the question about enclosing your patio.

It sounds like the temperature and humidity conditions are reaching dew point as moisture will then condense on the underside of the metal roofing. When warm air comes in contact with the cooled sheeting, the drips form. Do you experience this issue mainly in the mornings?

To stop these drips from falling within the newly enclosed area, you can install a vapour barrier under the sheeting to prevent contact between moist air and the sheets. Any drips that do still form will be directed down the sarking and out of the area. This type of installation would be most effective if you removed the sheeting before installing the sarking. Insulation batts can be used between the rafters and then cladded over with HardieFlex sheeting to complement the sarkings installation.

If you post some images of the area, it will give our helpful members an idea of what you're working with, and they might have some other solutions for you.

Please let me know if you have any questions.

Mitchell

[condruss]

Hi Mitchell,

Thanks for the response. The problem occurs mainly in the mornings. I’m not sure how to go about installing any product as it is a single sheet. I’ve included some photos. Your advice and help is appreciated

 

 

 

[MitchellMc]

Thanks for the images, @condruss.

OK, that's a bit different. I presumed there would be some structural elements (rafters) supporting a roof over that distance. Since this isn't sheeting on rafters, it negates my previous suggestion.

If it is a single sheet, it limits your ability to fix anything to it as well. You couldn't really baton out the roof and install sarking or fibre cement sheeting, as the screws would penetrate the roofing sheets, leading to all sorts of headaches.

Let me mention @TedBear, @Brad and @tom_builds to see if they have any thoughts. My colleague @EricL might also like to join the conversation.

Mitchell

[TedBear]

That's a tricky one @condruss. You are fighting the forces of nature outside, where nature usually wins. 

Options will depend on how far you are going with your alterations.

I'd suggest that you either try to insulate the bottom of the metal somehow, such as stick on rubber strip https://www.bunnings.com.au/moroday-750-x-10mm-x-1-8m-adhesive-foam-roll_p4000005,  or 

prevent the condensation from forming into drops by applying a textured paint. It needs to be rollered on, or dabbed. You could even try gluing on rubber backed tiles.

If you are enclosing a section, could you design that section to have its own ceiling? Then you could put insulation in that area at least. 

[condruss]

Thanks for your comments. All great ideas. We are thinking about turning a section into a room that would have insulation and a false ceiling but would like to treat whole area first. I’m curious about the textured paint. How would this work? Does it have sand or grit in it? What qty would I need for a 10x3.5 area? How many coats? What would I clean and prep roof with? Here is another picture from this morning. Although not beads you can see moisture. Thanks Shane 

 

[TedBear]

Hi @condruss , Yes, textured paint has grit in it. It should give some insulation from the cold metal and also the rough surface will make it harder for any moisture to form into drops, so it can then just evaporate away with air flow.

Another option would be to mount some fans on the wall and have them blow air across the ceiling, but the passive ideas don't require any management by you, once installed. You could just use the fans before you intend using the outside space. 

Quantities and prep for your situation  would be best discussed with the paint department, but it tends to be sold in large tins and is reasonably priced. I used some on a sunroom wall to hide the many patches from alterations and applied with a fluffy roller. Maybe @EricL can also add something there, he seems pretty good on products. 

[condruss]

That’s great news for the textured paint. Can I get this to match the colour of the patio roof? What quantity will I require for a 10x3.5 area,  what equipment and materials and what to use to clean and prep the area? Roll on sounds best application. I’ll have to order online and arrange pickup. Thank you all 

[MitchellMc]

@condruss,

@EricL will be back on the site after the weekend and will share his expertise with us. However, you'll find that most commonly available textured paints are compatible with brick, cement render, fibre cement, and masonry surfaces. I haven't personally heard of any that will adhere to a powder-coated surface. We might need to investigate with our suppliers to see if there is a primer that you could use that would allow the paint to adhere in this particular application.

Mitchell

[condruss]

Thanks Mitchell. I hope the paint will adhere. I’ll wait a response. Ta