Exterior masonry paint peelinf off like wall paper.

[sierragls]

Hi, new to the forum.
I have a hose that i have been asked to paint for a friend.
Before starting i noticed that some of the masonary paint was lifting, so i gave it a pull and the paint is peeling of in large strips like wallpaper right back to the plaster.
Has anyone any ideas what would cause the paint to peel off like this and what the best course of action to take is.
I don't want to start pulling the paint off and then end up peeling it off the whole house.

 

[jbonding]

Ive heard a waterproofer in your top coat on render can cause this

 

[Third_Eye]

Yep, somebody could have used an clear waterseal in the past without the next owner knowing. Then the new owner painting over it. Therefore causing the symptoms you refer to. What else can cause it is to thick of an masonry paint been used over porous plaster work. Even some people use vinyl silk on outdoors resulting in the symptom you mention. I personally would take the lot off.

 

[sierragls]

Would this xplain why tall the layers of paint peel off and it goes right back to the plaster?
is it advisable to take the paint off the whole house?

 

[Third_Eye]

Yep, take the lot off. If you dont then all you are doing is delaying a longterm problem.

 

[Zampa]

Yep I agree with all that too...although if the paint is thick I doubt if its down to waterproofer..because it hasnt been widely used for that long..but again its a possiblity

But it could be so many things..including the wrong paint in the first place, too thick, too thin, maybe plastciser in the render, too much sand in the render which causes the surface to become powdery or friable

So may reasons...but dont concern yourself with them..strip the stuff off and then let us know what the surface is like before you continue

 

[sierragls]

One wall has been almost completly stripped. The plaster is good, but the surface is quite powdery.
When i start painting the wall, is the a base coat or primer that should be applied first, or can i just start straight away with the emulsion?

 

[Zampa]

No!...dont just start painting it again..

Give the walls a good hosing or dusting down then you can either give them a coat of stabilsing solution or if you intend to use a oil based masonry paint...a thinned coat of that first..its self sealing.

 

[Nige F]

Ive heard a waterproofer in your top coat on render can cause this

I heard it was in the scratch coat that caused it

 

[jbonding]

Ive heard a waterproofer in your top coat on render can cause this

I heard it was in the scratch coat that caused it

Imposible

 

[Zampa]

A coat of thompsons water seal can cause damage...if you apply it over masonry paint I think you have to leave it for about five years before to can paint over it

Dont ask why anyone would want to do that anyway...but they do!