Ask Your Question

Angie's List Answers is the trusted spot to ask home improvement and health questions and get answers from service companies, health providers and consumers. For ratings and reviews on companies in your area, search Angie's List.

Top 30 Days Experts
Rank Leader Points*
1 kstreett 240
2 Guest_9020487 110
3 Guest_9190926 105
4 GoldenKid 100
5 ahowell 95
6 KnowledgeBase 95
7 skbloom 80
8 Guest_98024861 70
9 Guest_9311297 70
10 Guest_9400529 70

*Updates every 4 hours

Browse Projects By Category

Question DetailsAsked on 4/14/2016

Should my painter use bleach while powerwashing my tudor house's wood trim?

I've been trying to find a painter to paint my tudor house and I've gotten varying responses. One painter's instructions says "If there are signs of mildew growth (little black dots), be sure to install the black chemical injector tip and apply bleach generously to the entire area. After you let the bleach solution set for two minutes, use the yellow tip and fresh water to rinse the surface thoroughly." He also mentioned that if you didn't get rid of the mold with a bleach then it would come back through the exterior paint after the fact.
I asked another painter if they use the bleach and they said it was an amateur move and that the original painter must not know what they are doing and how the bleach would soak into the wood and make it more difficult for the paint to adhere. Not being an expert painter I was wondering what are the merits of each method. Thanks

Do you have the same question? Follow this Question

1 Answer


The mold definitely needs to be killed first - and the overlying primer should have mildewcide in it or added to it as well to handle any unkilled spores. Bleach - as in Purex bleach or such - commonly has gelling agents or surfactants in it that make overlying paint have problems adhering - hydroxen peroxide would more commonly be used for mold killing in this application as it largely evaporates and is readily soluble in water when washing afterwards. Or use a brandname product (DuPont, 3M, PPG, Sherwin Williams, Olympic, etc) specifically designed for mold kill on siding - some combine the detergent and mold killer in one product. I would NOT use one of the off-brand ones or "green" products - from what I have seen and heard, most of them are a no-go as far as effectiveness, especially the "orange oil" and similar totally organic ones.

Two minute set time has been shown to be too little, especially with black mold as opposed to brown mold or mildew - you should keep the surface wet with the "bleach" for at least 5 minutes for essentially total kill, even though that does cause minor wood damage.

You did not say what the second painter proposed to do to kill the mold - but if nothing, then throw him to the street because you WILL get repeat mold appearance through the paint if the mold is not positively killed before priming.

Answered 4 years ago by LCD

Related Questions

Terms Of Use
Privacy Policy