Painting rendering covered with moss

[Peter Chapman]

The upper half of my house is rendered, not smooth render but, textured
which seems to enhance moss growth to the extent that the rendering
needs painting before the actual paint shows signs of ageing although it
will last up to 5 years before the moss growth becomes too bad.

The moss grows on the East and North side of the house and has
previously just been painted over with 2 coats each time.

Before I repeat the cycle, is there anything that can be done to reduce
the re-appearance of the moss as in special paint or specific
preparation prior to painting?

Grateful for any helpful suggestions/tips.
--
Peter

[Dave Liquorice]

On Mon, 16 Aug 2010 08:19:14 +0100, Peter Chapman wrote:

> The moss grows on the East and North side of the house ...

Do you really mean moss or algae or lichen? Moss usually need more
than just a painted surface to grow on.

> and has previously just been painted over with 2 coats each time.

Moss is also a small plant rather than a surface film. How ever
painting directly over moss/algae/lichen without first removing it
strikes me as a very bad idea. Both Sandtex and Dulux sell fungicdal
washes which you apply and rinse off, I'd rinse with a pressure
washer but at a distance and not with a "dirt blaster" type nozzle.
This is preparation to get the paint film to adhere properly and last
without flaking off.

If you current paint film is still sound it probably only needs a
wash down, gentle pressure washer again. Some paints do have
mold/algae inhibitors built in but I don't know how effective they
are. The north and east facing wall will be prone to algae I doubt
there is much you can do to prevent its growth.

--
Cheers
Dave.

[Tabby]

Textured render is much worse than smooth for this. If you decide to
externally insulate, do render it smooth.
Cut back overhanging trees and anything else that shades the house,
thus increasing dampness.
Adding a little powdered copper to the paint works wonders.

NT

[harry]

Hire yourself a high pressure ware jet machine to get it off. If it
won't shift it (and it might not) it will have to be sandblasted off.
Painting over moss is a bad idea.
Then you need a fungcide or bleach. Then you need to make any repairs
to the pointing. Then you need to decide if you need a stablising
coat. Then you can repaint it. Keep some bleach in the house and
hose down twice a year to keep the stuff away. Get the smooth finish,
it's less problems with moss.

[Peter Chapman]

In message
<17bd7ce9-f5fc-4b8b...@z10g2000yqb.googlegroups.com>,
harry <harol...@aol.com> writes

Thanks for the useful suggestions guys. I have a better idea as to how
to proceed.

--
Peter