How to fix loose paint and render on exterior wall?

[hesamshimi]

Hello

My exterior wall render and paint is patchy,  loose and blistering in lower part, like 10-20 cm from the ground and mostly below the weepholes and the damp barrier, but mear the main entrance above the barrier, as in attached pics. Any idea how to fix this to look better and what material I need to use is very much appreciated. 

Cheers

[Jewelleryrescue]

 Hi @hesamshimi 

Looks  like your damp course working at least . but the  paint below that line is under stress.

All you can do is use  some sort  of  paint stripping tool like a wire  brush on a drill (wear a  pair googles for saftey) strip loose paint back and then  repaint with the one of  best under coat designed for concrete and bare pathing.

Dulux 1L Concrete & Paving Bare Concrete Primer I/N: 0417959  $19.90

You  can just cover those marks quickly  with any white paint acrylic and it will last a couple of years less with flaking areas. Depends upon your  free time to start a new  project.

After under coating use any all weather paint acryilic from good brands and hope the water moisture wont effect under coat too much. No  way to tell bofore application.

[hesamshimi]

Thanks @Jewelleryrescue 

How about using a water proof undercoat like: https://www.bunnings.com.au/crommelin-1l-exterior-grade-brushable-waterproofer_p0961573?store=8182&g...

Then coat it with paint.

Would that be better you reckon?

Cheers

[Jewelleryrescue]

Hi @hesamshimi 

Sticking  any paint to a wet wall well is a tricky business and  we are in the hands of the paint manufacturer how well it works in each  stituation.

The ultimate solution  is a cement based paint that will not only stick to a cement wall but will seal it /waterproof to stop water coming out of the brick and  or going in.  I used it to seal a cement fish pond brick work as a proof it works.

You make this by  adding Betta Super Concentratete cement additive.  Use  off  white or Ivory cement (Not Grey as color dark)

Mix design for Sealing Slurry: 1 part of cement + 1 part of fine sand + 1 part of Admix Super liquid.

Method brush it on the wall 2 to 3 coats with straw  renders brush let it dry between coats.

Dunlop 160mm Renderers Brush I/N: 0960322 $28

Once finished  paint over the top. as you wish that area wont suffer from  rising damp again.  (Rising  damp is water  plus it becomes partly acidic is the main concerns and why paints fail.)

In case you want to explore this path more 

https://www.bondall.com/water_proofing/betta-admix-super-concentrate/

I didnt meantion  this before as it is a more extreme painting step that will look more textured than the rest of the wall.

Hope this helps

[MitchellMc]

Hi @hesamshimi,

Some great advice provided there by @Jewelleryrescue.

Instead of the Crommelin 1L Exterior Grade Brushable Waterproofer I'd recommend you consider using Crommelin 1L Flat Aquablock Waterproof Primer Undercoat. It's designed for masonry surfaces and provides a water-resistant coating that is ready to paint over.

Mitchell

[hesamshimi]

Thanks very much for the useful information and tips mate.