Moss on limewash

[MetManMark2]

Hi there
This summer it will be 6 years since we re-rendered and limewashed our house. We love it. However, it is time to apply more limewash. In a few places at the edges of window sills / underneath the chimney there is moss growing. I am assuming that I need to get rid of this before applying more limewash. What would people recommend for doing this? The worst bit is under the chimney (just below where the leadwork is) and this is pretty high up so I have yet to investigate how well established this is! What products would people recommend or should I give my pressure washer a try?
Thanks in advance
Mark

 

[TheForge]

A power washer should blast off most of the moss but you’ll need to treat the areas affected to dissuade it growing back. Also, reapplying a limewash containing a dry film biocide will delay regrowth.

The affected areas should be scrubbed well with a suitable fungicide/algacide.

 

[Flyfisher]

I'd be very careful with a pressure washer; it could do more damage than cleaning!

We limewashed part of our house last summer and found that any moss/algae could be easily removed with a decent brush and a diluted bleach solution, though I'm sure there are proprietary chemicals also available. I guess much depends on the extent of the moss/algae.

 

[MatthewC]

I'd be very careful with a pressure washer; it could do more damage than cleaning!

We limewashed part of our house last summer and found that any moss/algae could be easily removed with a decent brush and a diluted bleach solution, though I'm sure there are proprietary chemicals also available. I guess much depends on the extent of the moss/algae.

I removed a lot of moss from a parapet wall on the church in the last 2 years, using a plastic windscreen ice scraper and a nice stiff churn brush (the one I use on lime mortar). No chemicals at all. I have yet to see any regrowth and when it gets half as bad as it was (probably 5 years?), I'll do it again, as it's easy to reach.

NB the plastic scraper is no longer good for its original purpose!