Clean ext. wall before painting?

I'm about to re-paint a garage with same color --BM Navajo white.
It's kinda messed up, with bald patches where I had adhered those little round discs that held vines.
Question: Should I hose it down with Spic 'n Span (and thorough rinse) before painting?
Or superfluous?
TIA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'd certainly hose it down if there is a coating of dirt or dust on it. I'd do it a couple of days before painting to let it dry well.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@forteinc.com wrote:

Let dry well.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Norminn wrote:

* Sand the spots where the discs were so they don't show through the new paint. * Caulk where needed. * I would use TSP (trisodium phosphate) instead of Spic 'n Span. SnS might not wash off completely.
--
Steve Bell
New Life Home Improvement
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 31 Oct 2008 13:09:51 +0000 (UTC), "SteveBell"

Thanks to all for suggestions.
I forgot to mention that this wall has plants, up to 3' tall, growing right up against it. PITA to jam plastic back behind the plants, but gotta do it.
Question: Between the two suggestions for cleaning:
1. Spic 'n Span + bleach, then rinse
or
2. TSP , then rinse (I understood TSP needed very thorough rinsing as well. T/F?)
Which would be LESS damaging to the poor lil' plants? There is bound to be runoff; plastic won't protect entirely.
TIA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
clipped

paint and dirt off. Bleach helps kill mildew so's new paint doesn't peel.
For plants, tie them up with some old pantyhose - cheap, disposable, don't damage the plants. Cover plants with plastic during washing, if you are worried. Plastic tarp will do fine, but don't leave on with hot sun shining, cause that can burn the plants. In my experience, bleach won't hurt plants as long as they are rinsed.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@forteinc.com wrote:

I don't know what's in S&S; that's why I recommended TSP. I know that TSP in small amounts won't hurt the plants. It washes off very easily, too. If S&S has detergent in it, it will take lots of rinsing to remove.
Instructions for deck cleaners always say to wet the plants down first, then cover them, then do the work, then uncover and wash them off. I do that with other types of chemicals, too.
--
Steve Bell
New Life Home Improvement
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Oct 31, 12:30am, snipped-for-privacy@forteinc.com wrote:

Read any paint can, they require you to have a clean surface, paint wont adhere long on dirt and mold plus any warranty will not exist.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It definitely helps to scrub it down with detergent and a strong bleach solution. The bleach will actually soften the old paint, and thereby make the new layer of paint adhere better.
- Logic316
"A democracy is when three wolves and one sheep vote on what to have for dinner."
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.