Anti mildew/fungus exterior paint additives?

Hey workshoppers,

I've been repainting, starting at the back of the house . The walls are HardiePlank Fibre cement (wood look). This looks good

I'm using British Paints 4 seasons low sheen..Added a nice neutral grey tint

So here's the issue. one side (the south) of the house never, ever, ever gets sunlight, not even reflected, and that side of the yard always seems to take longer to dry (even with good drainage), and it's a narrow pathway. Consequently, there is a mildew or mould build up that we are always fighting against.

I've been looking at paint additives, or some other solution.

So, should I put an additive in the undercoat, the top coat or both?

My guess is I have to do a serious scrub of the current mildew before I prepare the surface am I right?

Recommendations appreciated.

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Comments

MitchellMc

Hi @Walter,

A good scrub down of the current surface with Sugarsoap to remove any mould or mildew should suffice. If it's terrible, you might find it easier to use a product like 30 Seconds 2L Spray And Walk Away With Rapid Hose End. Make sure you rinse the wall with fresh water and let it dry before undercoating. Get that new pressure washer onto it to blast any loose mildew or mould off the paintwork.

I'd recommend adding Protite 75ml Mould Defender Paint Additive to the topcoat. Unless the mould is living in the wall and penetrating through the paint, I can't see any reason to add it to the undercoat, though you could for extra protection. You might also like to consider switching to gloss paint for that side of the house. Gloss paints are easier to clean, and the mould will find it harder to penetrate their surface. Whether you use gloss or not, you'll find the British Paints 4 seasons low sheen is specially formulated to resist mould. As paint ages, it becomes worn and more porous. I'm sure you'll find with the new coating, the mould will be inhibited.

Let me mention @redracer01 as he is particularly knowledgeable about paint application and might have some additional advice.

Please let me know if you have any questions.

Mitchell

Walter

https://www.workshop.bunnings.com.au/discussion/comment/13811#Comment_13811

@MitchellMc ,

Looks like a trip to my local Bunnings is on the cards😂

That 30 Seconds Spray thing looks like the job, and yes, the new high pressure washer will be doing duty as well.😎

I've got so much of the BP 4 seasons low sheen, I think I'll stick with it, but mix in the additive.

We've been keeping the mould down, and it hasn't crept in. It's just annoying.

redracer01

https://www.workshop.bunnings.com.au/discussion/comment/69416#Comment_69416

Hello @Walter

All very sound recommendations from @MitchellMc I would only add that aside from spraying the wall, I suggest spraying the ground as well to control the mould. The 30 seconds spray is plant friendly and should be good enough to combat the mould infestation that you currently have. As for the primer I suggest using Dulux Precision mould and stain blocker. It's formulated to resist mould growth and infestation. Is there no possibility to at least get some wind or breeze to pass through that section of your house? If not then an occasional spray of 30 seconds should suffice to keep the mould growth to a minimum. Another option to get sunlight in to that area is possibly to build a reflective wall or small fence that will deflect ambient sunlight in to that section. Hope my suggestions help.

Cheers,

Red

Walter

https://www.workshop.bunnings.com.au/discussion/comment/97725#Comment_97725

Well, today I went and bought the recommendations @MitchellMc gave, and a few more besides.

Went to my local Bunnings, and the store was hugely busy. Busier than I have seen on a Saturday.

People were all wearing masks, and everyone I spoke to was buying stuff for home improvement for the next few weeks of lockdown. That's what prompted me to make the trip too.🤣

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