Outside house wall, Bubbling paint.

SCOOP 64

I have a problem with a patch on my house wall with Bubbling paint, started last year so just pealed it off but the render came off too so just painted over it, but its back again and spreading, i take it it is water getting underneath paint, what should i do with it now ?

Gun Monkey

SCOOP 64 wrote: »

I have a problem with a patch on my house wall with Bubbling paint, started last year so just pealed it off but the render came off too so just painted over it, but its back again and spreading, i take it it is water getting underneath paint, what should i do with it now ?

I had this a couple of years ago, it was a newly built wall, left for a couple of years after building which was painted in the summer after being properly dry for several weeks.

The following spring the paint started to buble and blister and eventually peel away. Eventually it became so bad that i had to spend days power washing the whole thing back to bare render, removing nearly all of the paint and then repainting from scratch. The only difference from your situation was that my render didnt come away or appear to be in poor condition. I was putting it down to a poor paint batch (even though i had bought a leading brand paint from a leading highstreet chain store) as it didnt seem to reoccur and is still fine a couple of years later. I dont know if its of any use to you but i spoke to several professional painters at the time and they recommended not buying any of the expensive paint additives that paint stockists will try to sell you. Apparently they would never consider buying these, they just clean a bad wall back to a a clean, flake free, dry surface and add white pva glue to the undercoat layer and then topcoat as normal. You can buy white pva gle from most good paint stockists in 5 ltr buckets or even bigger depending on what you want. Hope this is of some help to you, let us know here how you get on.

SCOOP 64

Do you have to bring it back to bare wall or can you scrape out the bubbles and paint the glue over paint , then repaint ?

Calahonda52

Gun Monkey wrote: »

I had this a couple of years ago, it was a newly built wall, left for a couple of years after building which was painted in the summer after being properly dry for several weeks.

The following spring the paint started to buble and blister and eventually peel away. Eventually it became so bad that i had to spend days power washing the whole thing back to bare render, removing nearly all of the paint and then repainting from scratch. The only difference from your situation was that my render didnt come away or appear to be in poor condition. I was putting it down to a poor paint batch (even though i had bought a leading brand paint from a leading highstreet chain store) as it didnt seem to reoccur and is still fine a couple of years later. I dont know if its of any use to you but i spoke to several professional painters at the time and they recommended not buying any of the expensive paint additives that paint stockists will try to sell you. Apparently they would never consider buying these, they just clean a bad wall back to a a clean, flake free, dry surface and add white pva glue to the undercoat layer and then topcoat as normal. You can buy white pva gle from most good paint stockists in 5 ltr buckets or even bigger depending on what you want. Hope this is of some help to you, let us know here how you get on.

Because they want to get the job done, get paid and be well gone before the issues start.
PVA is water soluble, enough said if used in external paintwork.

OP:
started last year so just pealed it off but the render came off too so just painted over it,

Does not compute: what do you understand by render?

SCOOP 64

Calahonda52 wrote: »

Because they want to get the job done, get paid and be well gone before the issues start.
PVA is water soluble, enough said if used in external paintwork.

OP:
started last year so just pealed it off but the render came off too so just painted over it,

Does not compute: what do you understand by render?

Proberly what i thought is render isnt, dont know if you can see it, on left of photo a patch which is slightly smoother then rest, when i scraped bubbles off, in the flakes of paint that come off seems to be grity, not smooth paint flakes, leaving a smoother patch underneath.

Calahonda52

SCOOP 64 wrote: »

Proberly what i thought is render isnt, dont know if you can see it, on left of photo a patch which is slightly smoother then rest, when i scraped bubbles off, in the flakes of paint that come off seems to be grity, not smooth paint flakes, leaving a smoother patch underneath.

Okay, can't recall the correct name now, too much vino, but its not the render so happy days

I don't know if its water getting in underneath or the paint just not sticking, not my department!

Gun Monkey

SCOOP 64 wrote: »

Do you have to bring it back to bare wall or can you scrape out the bubbles and paint the glue over paint , then repaint ?

I was going to just scrape the visible bubbles /patches of flaky paint but to be honest im glad i powerwashed it because most of it came off in huge big sheets and chunks, showing that the bond between paint and wall beneath was almost non existant. I wasnt using a commercial machine, it wasnt very high pressure and still it just came off in lumps even where there were no visible bubbles or flakes. In fact, where it was flaky etc it came off in smaller bits, its the parts that werent flaky that came off in sheets. I think if i had just scraped the visible flaky bits then the remainder would have continued to deteriorate under the new paint i then applied and i would have been in the same situation again. I choose to go this route as i could visibly see the flaking spead over time and what was apparently good paint one day was bubbled and flaking a couple of weeks later and so it progressed. I saw no alternative but to take it all off. No point putting good paint up over bad, its expensive enough when you are buying the quantities needed to cover multiple coats on a large-ish 2 storey house.
With regards to the pva glue, i stand to be corrected but i believe there shouldnt be any issue adding water based pva glue to water based emulsion paint? The recommendation came from a good friend who is a decorator by trade and has been doing this for his entire working life of almost 30 years. I then mentioned it in the local specialist paint supply place for a second opinion and the owner there said all his trade customers use it that way. He gave me a mix ratio but im not certain i remember the figures correctly so i wont quote it. This was from a guy who was selling these paint additives, some of which are approx €60 for 5 liters which will only treat a couple of 10 litre buckets of paint! To me thats just ridiculous money, id sooner knock the plaster off the wall and redo that, it would be a more definite fix to the issue. Thats my 2 cents anyway.....if i can be of any further help then just ask.

Gun Monkey

SCOOP 64 wrote: »

Do you have to bring it back to bare wall or can you scrape out the bubbles and paint the glue over paint , then repaint ?

P.S. - just reread your post, you dont paint the pva onto the wall, you mix it into the bucket of paint at a set ratio before you apply the paint/pva mix to the wall, say 1 or 2 liters of pva to a 10 liter bucket of paint, but as i said above im not certain of the ratio so i would suggest asking in your own local paint supply specialist, i would be surprised if they couldnt advise you of the most commonly used ratio.

martinr5232

I had this problem a few years ago so i started scraping the loose bits off i thought i was doing a grand job till the first bit i done started flaking again.
I ended up power washing the whole house. Let it dry for a few weeks then painted it with an oil based stabaliser then two coats of paint still looks as good as the day it went on.

My neighbour done his the same time he couldnt understand why i was going to all the trouble power washing and priming. His is like yours now again.

dodzy

Scrape off the offending paint.
Brush/roll on diluted PVA (polybond) to affected area.
Repaint (2 coats) the following day.
Job done.