Painting & Wallpapering/painting
QUESTION: Hi, the paint on my mom's house is pealing. We can't afford to get the whole house painted, so what I was going to do is just scrape off the old paint and repaint it with a paint and primer in one. We had someone at our house who says he knows about painting and if I do that it will cause more harm than good. He said it will just peal right off. He touched the spot I scraped and white dust came off on his hand. He said I had to pressure clean it first to get off the white stuff. Is he right or can I just do what I had planed and scrap off the old paint and just paint the scraped off places?
You neglected to tell me what the substrate is that is peeling. I will answer assuming it is some sort of render concrete or similar, if it is timber then it is a different problem.
You seem to be describing efflorescence caused by retained moisture which will destroy the key of surface coatings. The white hands of the painter gives me the hint and he is right it will have to be removed. However PLEASE do not pressure wash or introduce ANY further water.
Firstly the source of moisture has to be located it could be a leaking pipe from inside or a broken gutter or just design of windows etc which is allowing ingress of moisture.
Then remove all the white efflorescence by stiff bristle brush (like a yard brush) do not use A WIRE BRUSH as this introduces splinters of metal which will rust under water based paint. You can repair the peeled areas but a one coat system is not appropiate as the higher the build of the coating will affect the key. My spec after the preperation described above would be to apply a thinned coat of the paint you are going to use up to 50% and ensure that it penatrates the surface and then apply subsequent coats with less water say 10 t0 15% thinned until i tblends in with the sound paint.
If the substrate is timber please contact me again.
Hope this helps.
---------- FOLLOW-UP ----------
QUESTION: Hi, thank you for your help. Our house is concrete, but it is also the under hang of the house that is pealing too. Could this be happening because we live in florida? Our grass is dead and when it rains the water does come back against the house, I wonder if that could be the problem, but we can afford new grass, I guess I could just build up the soil around the house.
Yes I think you may have the solution, if water can reach the substrate above the DPC (damp proof course)then rising damp may be the problem. The extreme temperature of Florida will not help perhaps drawing water more vigourously through the concrete.
If you build up the soil make sure it is not touching the building.
Hope this helps.