How to install wall vents to improve air circulation and reduce mould?

[haveacrack92]

I am looking to install some wall/ceiling vents to help improve air circulation within our wall cavity. Our house is quite old and we had a minor mould issue so I am hoping to DIY install some vents to assist in prevention of any mould return. I would love some advice as to what type of vents would work best? How many in each room? Are internal or external wall vents better? Any tips on installation?

Thanks so much, really appreciate the feedback.

[MitchellMc]

Welcome to the Bunnings Workshop community @haveacrack92. It's great to have you join us, and many thanks for your question about installing ventilation.

Could you tell our helpful members a little bit more about the mould issue you've experienced, as that would help them better understand the problem at hand? Was it in every room? Was it just minor surface mould on the walls? 

I have an older home that has extensive mould issues. However, it already has vents in each room. You've mentioned that you want to improve air circulation in your wall cavities; wall cavities typically do not need ventilation. Do you have a leak on the exterior, allowing moisture to penetrate the cavities?

I think it's important to understand where the moisture comes from to prevent mould from developing. Structural issues can allow water to enter the wall, wetting your interior lining, and then there is moisture buildup in the home, mainly seen in bedrooms, kitchens and bathrooms. This is most prevalent in Winter when you'll find moisture on internal windows and walls. In my case, I have both of those issues going on.

Since this was a minor mould issue, and if you believe there's moisture in the wall cavities, I'd be inclined to install at least one external vent in each wall and then consider a different coating for your walls. Touch wood, I've had great success by including Protite 75ml Mould Defender Paint Additive into my new paint coats, and I went as far as to change from low-sheen paint to semi-gloss. Semi-gloss is less impervious to moisture and cleans far better, making it hard for mould to take a foothold. You could also look at applying Crommelin 4L Flat Aquablock Waterproof Primer Undercoat to any particularly damp walls, then over-coating with a paint and including the Protite Mould Defender.

Regarding installation, what are your walls constructed from?

Please let me know if you have any questions.

Mitchell
 

[haveacrack92]

Thanks so much for responding to my post.

When we bought our house, it had a really old roof with many leaks that would occasionally come through the ceiling/cornice. We have since replaced the roof which has solved all issues of leaks, but when I pulled out an old wardrobe I found some surface mold on the walls. We have since removed the mold and replaced the gyproc that was affected. The plasterer recommended installing some external wall vents to improve with any air circulation to prevent any moisture holding in the cavities. 

What sort of vents do you have at your house to improve air circulation? 

As for the construction of our walls, we have Gyproc for the internal walls and then the exterior of our house is a vinyl weatherboard.

Thanks so much for those links, I will have a look at them now.

[EricL]

Hi @haveacrack92 

Just to add to the suggestions made, I recommend engaging the services of a roofing specialist and asking them about the installation of Whirlybirds or Natural Roof Vents in combination with eave and internal vents. This will provide excellent ventilation and air circulation in your roof cavity. Plus, it has the added effect of lowering the temperature as well.

An excellent vent to install in your laundry for example is the Bradford 250mm CSR Round Ceiling Grill Vent. This unit allows you to open and close the vent when the seasons change. You can also install an Arlec 250mm White Exhaust Fan to draw the air in the room out through the ceiling. But it's best to speak to your roofing specialist and see what they recommend for your houses configuration.

If you have any other questions we can help with, please let us know.

Eric