Stop mildew/algae build-up on old vinyl siding?

Question

I need to figure out how to stop this mildew or algae stuff that shows up on one of my rental house's older vinyl siding.

I end up having to pressure-wash this crud off at least yearly, but it really needs it 2-3 times per year!  It's really ugly.  What can I do to prevent it from coming back all the time?

The siding is otherwise in excellent condition.

Account Closed · Answer

Zinc on the roof.

You can buy Moss B Gone and sprinkle on the roof. You can buy special zinc strips to put on the roof, or you can place galvenized chicken wire along the ridgeline.

Christopher Davis · Answer

I have this same problem on my personal home. There is a product called JOMAX, you can find it at Home Depot or Lowes.Mix per instructions w/ bleach water in a pump sprayer and just soak the affected area. Then take your hose with a good sprayer attached and hose the mildew right off. If you've got it bad you may have to repeat or let it soak a bit . but do not let it dry on the siding, or you,ll just have to start over. I use this every other year as the mildew shows up. If I just clean it off, the mildew comes back that same summer /fall so the JOMAX will inhibit growth for a time.
Be sure to spray off any desirable plants w/water before and after using this.
  Good Luck
   Chris

Frank Adams · Answer

I'm not sure how humid it is in your part of the state, but I've seen lots of houses in Houston with this problem. SOMETIMES the problem is caused by the idiot who decided to put vinyl on OVER THE TOP of the old, maybe faux board siding.

If there was moisture in the old siding it's going to manifest itself by creating condensation on the outside. I've seen houses where the original siding was just crumbling from years of retaining moisture.

Is there a way you can easily pull some of the siding off and see what's going on underneath?

Cleaning it is just treating the symptoms, not the cause. You need to find out the cause.

Frank

Just Don · Answer

This is probably on north side of the house.  I never had that prob but if I did I would try that mold preventer that Menard's sells for interior use.  OR look in same place for a similar outdoor product.

Is this well shaded?  Any possible way to increase sunlight by trimming trees,bushes etc?

Stop mildew/algae build-up on old vinyl siding?

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