What can I do to prevent a brick patio from getting
Mold or mildew again
After powerwashing the patio.

I am assuming you are talking about house siding, right? If not, please write back. If you used a mildewcide it should kill not just clean most of the mildew. A periodic spray of a 1:3 solution of bleach/mildewcide and water will prevent regrowth. If it is on a roof you can install a copper or zinc strip at the peak. The rain reacts with the metal and prevents mold and mildew.

Prevent mold and mildew on what kind of surface, after powerwashing ? It makes a difference to know; it could be a porous surface which would have to be treated differently then non porous.

Quote:

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Originally Posted by ballengerb1

I am assuming you are talking about house siding, right? If not, please write back. If you used a mildewcide it should kill not just clean most of the mildew. A periodic spray of a 1:3 solution of bleach/mildewcide and water will prevent regrowth. If it is on a roof you can install a copper or zinc strip at the peak. The rain reacts with the metal and prevents mold and mildew.

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What is the min. width of the copper strip for it to work, thanks

The copper is slid under the cap row of shingles and then leaves a reveal of about 4 inches. I do not honestly know if there is an actual standard. Maybe a roofer could help us out more.