Blistering Paint

Post by **Jing Jing** » June 8, 2014, 11:36 am

I recently repainted an interior wall that had been blistering. The painter prepped the wall by scrapping off all the lose paint and applying TOA acrylic contact primer before painting. Now six months latter the blisters are back. The wall is not in a bathroom. Is this groundwater coming up through the wall? Is there a way to fix this - water sealer or fungicide ?

Post by **pf-flyer** » June 8, 2014, 1:23 pm

What is on the other side of this wall ? Where is the source for this water ? IMO there is water being drawn out from in under the paint causing the paint to lift and blister. I had the problem in the U.S. and it was solved by a lot of scraping and cleaning the wall down as best as you can and apply a sealer ( Such as Dry-LOCK or something similar if you can find it ) , a good primer and then paint. I have had success also by sealing the outside of the wall if the source of the water is on the outside. Concrete is porous and water has no problem in percolating thru.

Post by **rickfarang** » June 9, 2014, 11:01 am

Blistering like this on the outside of my house turned out to be the first sign of an water leak from a pipe embedded in a bathroom floor. If your water pump seems to be pumping while nobody is running the water, be concerned.

Post by **Jing Jing** » June 9, 2014, 11:44 am

As far as I know there are no pipes in the wall. The damage extends for about 2m along the bottom edge. Both sides of the wall has similar problems.

Another area of blistering is on the exterior. It is in an area adjacent to a bath room. I was suspecting the floor tile grout is worn out in places and moisture is getting through and is bleeding out through the wall. If its a pipe - good grief!

Post by **fatbob** » June 9, 2014, 12:33 pm

It is 'rising damp' moisture coming up from the ground. Good builders lay plastic taped at joins under slabs, then a plastic 'damp proof course' is laid between slab and first block in the wall to prevent what your photo shows. Glad I built my house!

Post by **Jing Jing** » June 9, 2014, 5:48 pm

I guess it's scrape and repaint. Thanks

Post by **udonexp123** » June 9, 2014, 8:02 pm

That wont work. You need to drill holes an angle and fill it with a compound to prevent the dampness coming up. As the other poster stated good builders put a damp course in which prevents the moisture coming up generally to a height of 2 metres. If you google damp courses you will find this information on Australian sites.

Post by **Bonanza** » June 10, 2014, 7:24 am

I had a similar problem with a house in the Middle East and was told by the resident engineer that it was probably due to salts in the cement used to make the wall (blocks/render) - usually due to unwashed sand.

Post by **maaka** » June 10, 2014, 9:30 am

tile over it Jing Jing, and then will no longer be a pain, or any further continued repainting, filling, scraping etc etc...

Post by **kubotatim** » June 10, 2014, 10:05 am

No but the tiles will just fall off after a while!

Post by **Jing Jing** » June 10, 2014, 1:55 pm

The problem is TIT so I don't think I could find a worker who understands what to do. Most of the workers are either kids or old guys who are set in their ways. Most lack masonary skills. My brother is a contractor/builder but sometimes I wonder

brick and sand left out in the rain.

It sounds like the wall needs to be scraped down to the underlying brick in some areas and the bricks drilled and filled with a damp barrier.

The interior is on a rental so not worth tiling. Unfortunately tiling the exterior won't look good and apparently the damp problem will occur at the top of the tile.

Post by **fdimike** » June 10, 2014, 5:38 pm

Jing

Before you go through a lot of work try scraping a small test area and coating it with Sista D150 acrylic waterproof wall sealant. I had a peeling paint problem due to an incorrectly installed (uninsulated) A/C coolant line running vertically in an exterior wall. I scraped the loose bubbled paint and applied several coats of D150 and that curred the problem. I applied a couple of coats of paint afterwards and it has been fine now for at least 5 or 6 years.

Another suggestion is to scrape a small test area and apply a waterbased concrete sealant. There are numerous brands at every home center in town. ie Home Pro, Global House, Tool Pro Plus, Home Mart etc. let the sealant dry and apply a coat of exterior paint and wait to see if it bubbles as before or not.

I hope this helps.