Preparing outside walls for painting

[MikeJM]

I`m going to repaint the outside rendered walls of my bungalow and welcome any advice as to the best cleaning solutions to use as part of the prep.
Should I use sugar soap or what is best? The walls haven`t been painted for several years and one north facing wall has got green mould streaks on it (not unusual for the part of cornwall I live in). Whats the best way of cleaning this of?
Any ideas please?

 

[Zampa]

Brush a mix of 60% water 40% bleach over the mould..leave for 24 hours or so then use a pressure washer.

 

[MikeJM]

Zampa
Thanks for info. After a lot of overdue work around the garden etc I`ve finally got to the bungalow walls.
Thanks for the info re bleach etc, works a treat and walls have come up very clean.
A problem i`ve now come across while cleaning the walls is i`ve found several patches of blistered paint where i presume rain/damp has got behind the paint over the years.
How should i treat this? Cut out the blisters and just repaint as normal?
The old paint on the wall is quite thick so after cutting out the blisters I would like to "fine fill" the hollow surface before painting. If so whats the best filler to use etc?
Grateful for any help.

 

[Zampa]

Scrape to blisters off as much as possible..remove all the loose and then rub it down around the edge to remove any rough edges..

Give the bare area a primer sealer or slightly thinned masonry paint..then mix some PVA with water (ratio of anout 10-20% PVA) and use this to mix with any good powder filler like polyfilla or tetrion..

Dont over fill it..it sets very hard and the PVA helps prevent further damage by stopping it from becoming damp...fill it and finish it by stippling with a piece of sponge or flick some water on it as its drying and go back over it with a clean filling knife.

 

[MikeJM]

Thanks Zampa
Is normal PVA ok to use as or should it be a waterprooof type?

 

[Zampa]

Waterproof one will be better..

 

[MikeJM]

Thanks Zampa
Weather has been less than helpful but finally finished cutting all the paint blisters out and filling. Once i started i found a lot of patches that were `blown` so to speak.
I`ve now got a lot of filled exposed patches over the bungalow that i guess need sealing before painting. Am i ok to seal/prime using waterproof PVA? or thinned masonry paint? Or what is the best?
I want to do as good a job as i can (weather allowing) that will last as the weather can be quite rough down here in West Cornwall.
Thanks for the help.

 

[Zampa]

Id use thinned amasonry paint...if the weathers bad and your exposed then you might be better using th oil based variety.