How do you keep algae from growing on your house?

Liz R.
by Liz R.

I have one side of my house that does not get sun. When we bought the house two years ago we had it washed and repainted. I thought that took care of the issue. I noticed that algae is starting to come back. I put landscaping paper down and mulch over the top in that area. Did that help keep it at bay or make it better for the growth? Short of cutting down the trees how can I keep this unsightly stuff from growing?

  4 answers
  • Morgan McBride Morgan McBride on Jan 03, 2019

    I would powerwash it off.

    • Liz R. Liz R. on Jan 03, 2019

      I did. My question was how to prevent it from being there in the first place. Thanks for your reply!

  • Spraying Wet & Forget mold and mildew remover on a house. If you live in a warm, humid climate, mold and mildew will often form on the exterior siding and trim of your home. It's important to clean the outside of your house regularly to remove anymold or mildew and to clean it thoroughly before painting. https://www.todayshomeowner.com/video/preventing-mold-and-mildew-on-the-outside-of-a-house/

  • Vimarhonor Vimarhonor on Jan 03, 2019

    Hello Liz, sometimes I feel there is no solution. I have a similar situation I have a waterfront lake exposure in a cove thats somewhat downhill. There seems to be a consistent microclimate here where there is morning moisture collecting on the vinyl siding decking and deck rails. Actual water droplets on the white vinyl rails.


    Not having sun or great ventilation causes the mildew and algae, I have a moss problem too. We tend to do a powerwashing yearly keeping our fingers crossed the finish on the pt deck will last. We particularly like the oxi products.

    • See 1 previous
    • Vimarhonor Vimarhonor on Jan 03, 2019

      I understand your concerns and frustration.


      We were extremely disappointed with the preformance of our soild deck sealer to this newly constructed deck, it was rated for 7 years -the best possible warranty -from all the available deck sealing choices offered. Behr shipped us new sealer and cleaner to apply due to dissatisfaction and appearance/product failure.....and so far the deck appearance is holding up nicely with the secondary application. Its not an easy job for us to do at our age, certainly you dont want to be painting it every year. In a lot of ways we regret not using a composite decking.


      We have removed two of the cedar trees that shed and shaded the street side house. The deck is heavily exposed to sun extremely uncomfortable in the summer. The morning dew persists, the deck, gutters and siding does mildew, our mulch and rocks can get mossy. Central Virginia can be quite humid.


      I hope you find your solution - I hope you're not cursed with a disadvantaged aggravating enviromental situation like we are here.

  • Em Em on Jan 03, 2019

    The one side of my house was covered in algae when I purchased it. I sprayed it with windex and wiped it off with a wet rag. I did not reappear in the two years after until I replaced the siding because it was not the color I wanted. Algae is really not hard to remove and expensive cleaners and harsh chemicals are not necessary.