Painting cinder block

Old 05-30-09, 11:54 PM
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Painting cinder block

Hi folks

There is a 100 foot raw cinder block fence/wall on my property line. I want to paint my side of it. My neighbor doesn’t want to paint his side. That is OK with me since I don’t see his side. However, this guy runs his sprinklers night and day in the summer (Phoenix metro area) and I have been in his yard and seen the “water arc” stains on his side of the fence.

My question is: If I do all the right things to paint my side of the wall, good cleaning/power wash, use good quality [latex] paint etc, will the water from the other side wick through, even as vapor, and cause the paint on my side to fail anyway?
If so, or if it’s even possible, what can I do to prevent this, (short of volunteering to paint his side too).

A friend suggested doing the water seal step (e.g. like Thompson’s) but I’ve read where it’s a waste of time and money, that paint will do the same thing. Or that it has to be applied to both sides of the wall.

Thanks in advance for any advice and suggestions.
Old 05-31-09, 05:27 AM
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It is best to paint/seal both sides of the wall - top edge too! The moisture can work it's way thru the masonary and cause the paint on the other side to lift

Thompson waterseal does a decent job of sealing masonary, the only problem is it is short lived. It would need to be done every 6 months to a year.... and the substrate must be dry before it's applied.

Generally block fill is used for a primer on above grade block. If I was to paint just one side, I'd use drylok instead. It will help stop the moisture from going thru the block. Don't forget the top edge! For drylok to be effective, a heavy fluid coat must be applied - all the little pores in the block should be filled. Any/all cracks should be caulked. Finish with 1-2 coats of quality house paint. While on a job like this I would do everything I could to make it last, this is one job I wouldn't warrant if the other side wasn't painted.
Old 05-31-09, 05:25 PM
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You would be better off by applying a breathable cementious product like Thoroseal or colored stucco. The paint is going to flake quickly.

Last edited by Tscarborough; 05-31-09 at 05:45 PM.

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