Mildew on shady side of garage and exterior paint


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Old 01-27-17, 09:39 PM
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Mildew on shady side of garage and exterior paint

I have mildew/algae/mold/moss/green substance that recurs on the shady side of my garage. It is present on the painted cinder block wall. I have successfully knocked it back with direct hose spray once before. I wasn't intending to get rid of it that day and happened to be annoyed with it when I was out working in the garden. I knew I needed to spray it with bleach to make it go away more permanently but was quite surprised that it actually went away for a few good months/maybe over a year. Anyway I plan on intentionally ridding the garage of it in the upcoming months. I plan on spraying it with a bleach and water solution. I read somewhere to also add clothes detergent to help lift some of the other dirt away at the same time. My question is after I do this, if it successfully removes the visible green, is there anything else recommended to treat/prep the walls with before painting?

Additionally can someone give me some guidance on best paints for multisurface exterior work? The garage has asbestos and aluminum siding as well as the cinder block walls which are currently painted white on the exterior. The house has a different (older) type of aluminum siding and will be painted with the same paint. Any advice?
 
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Old 01-28-17, 04:01 AM
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I'd use a bleach and TSP mixture for the cleaning. Aluminum siding is bad to oxidize leaving a chalky film that paint won't adhere to. Old degraded paint will also get chalky. If washing doesn't remove all the chalk you should add Flood's EmulsaBond to the first coat of latex paint. Shady areas and north sides are more prone to mildew because they don't dry off as quickly from the rain/dew. Adding extra mildewcide to the paint can be helpful, either add it to all or just the paint for that side.

I'd use a quality latex house paint for all surfaces. Most masonry paints are of lower quality and won't hold up as long.
 
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Old 01-28-17, 09:00 AM
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The mildew is only on the painted cinder blocks. What is TSP??
 
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Old 01-28-17, 09:28 AM
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TSP - tri sodium phosphate, basically a heavy duty detergent.
 
 

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