Longest lasting white exterior paint?

[nuoptik]

Hi.

I live in a Grade II* Georgian Townhouse that is painted white. Fortunately we are not forced to repaint on a schedule like some are in Brighton (every 5 years), and we have only been her for a shade under three years, but the pervious owners painted the whole house not long before we bought it.

Our main problem is the green build up of what i believe to be algae. We face a tree'd park and it stops the sunlight from burning it up via UV, as well as giving it plenty of shade to grow in the trees and then jump to the houses (my science here might not be exactly well informed).

Since painting, and the scaffold alone to facilitate it, is very expensive I'd like to do my research and work out the best paint to use as we get nearer to needing a repaint. I know that since it's II* that we could still have it painted with lead paint, but i'm also an environmentalist so I'm not sure about that. I know that some paints claim to be anti fungal like Mapei Silancolor Pittura Zero, but don't know how effective that is.

Does anyone have any first hand experience with trying white anti fungal or leaded paint, and it's longevity compared to basic Deluxe Weathershield, which is likely what the block of houses has been painted with in more recent history?

I don't think i need to worry about breathability too much since the bungaroosh houses I think have been rerendered with cementious render in more recent times, and all but one of the 14 are painted with modern non-breathable paints - so that ship has sailed long ago.

Many thanks in advance,

Julian

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[malcolm]

The problem with plastic paints like weathershield is they are waterproof. That makes them a very bad thing to paint a lime rendered building as water gets trapped inside the wall unable to evaporate away. Being waterproof makes plastic paints susceptible to mould and algae. Water condenses on the wall when it's colder than the air and stuff grows on the water. This gets worse when the wall is damp.

I used limewash. My facade is cement painted in weathershield (or similar). It's a bit risky to use plain limewash as it can't penetrate into the previous coat of paint. I used Pozilime from Ingleby which has other stuff in it and that's worked well. Mould and algae don't grow on lime and it is unstained after 10 years. It does need re-doing as the rain has washed a bit off exposing the paint behind. Downside of limewash is it takes 4 or 5 coats.

 

[Cubist]

Lime-wash also possesses the capacity to resist algae blooms longer than other paints. The North side of this place is particularly prone as it is overshadowed by two nearby large yew trees and a hillside beyond them full of damson trees. Typically a couple of coats of Limewash will remain clean for 3 years after which I might need to brush off any new blooms and maybe add a new coat of wash.

 

[Cherryburn]

The other benefit of lime wash is that it's much easier to prep and overcoat when it does come time to repaint. Acrylic paints often need to be fully stripped back which is a massive pain. And it doesn't look anywhere near as bad when it is aged.