What is the best method for painting an outside block wall ?

Question

I have an old garage I want to paint and I want to avoid painting it again. Is there a trick to painting it (preparation) and what is the best paint.

Answer 1

I looked at the yahoo answers and I found a best choosen answer already so I cut and pasted the answer for you:

That is somewhat of a trick question. If it is outside, and have never been painted, you need to prime it with a good block filler, and then paint it with a mid grade to top grade paint., if it has been painted before and is outside, you need to power wash it with a power warsher that has a bleach injector, bleach helps kill the chalk and mold. You can run your hand along the surfice and then look at your hand and if it is chalky looking, then it needs to be powerwashed again. then put a sealer on it, then paint it. this way the paint will not peal. if you paint over a chalky serfice or a moldey serfice it will peal in 2 to 3 months.

Inside, well you cannot really powerwash inside, but you can take a spunge mop and a bucket 1/4 bleach, and 3/4 water and wash most of the chalk off if it is chalky and then seal it with a sealer and then paint it. and again if it has never been painted, use block filler and then paint. I hope this helps

(per doug level 3 member)

I hope that helps and once again sorry that I didn't know the answer

Answer 2

LISTEN, do not use a power washer on this project.  You do not need any more moisture in the wall or on the block.  If it is painted, you need to scrape the loose paint off.  Then you need to wash the entire surface area with an acid(muratic) solution and then rinse with a hose.  Let dry for a few days or more(with not rain in between).  You could use a block filler on raw masonry spots, or just use an acrylic paint color of your choice, sheen is up to you.  Paint two coats on entire surface and leave it alone.  To help protect and get more life of this coating, you should do the same process to the inside.  If you have water inside the block wall, you should drill some holes to let the water out.  good luck.