Asked on Mar 23, 2015

How to clean and get rid of mold on a Trex type deck

Phyllis Davis
by Phyllis Davis
We have tried all the commercial products on our deck to get rid of the awful black mold spots. They are gone temporally and then back with a vengeance. Last year we did not even get through the season. We do have an awning over it and that is the only area that did not get bad. My husband actually purchased some online cleaner and a separate sealer to us after and it did not work at all. Anyone have any DIY suggestion or any tried and true cleaners?
  8 answers
  • Connie A Wallis Connie A Wallis on Mar 24, 2015
    We have a gray trex deck that we've had for the last 4 years. We have used a power washer to wash the deck, which removes most of the dirt and build up from the winter (our deck is in Northern Arizona) but the black spots that sometime remain we've used a kitchen cleaner like comet and a stiff bristled scrub brush. It has worked well and hasn't damaged our deck. Good luck!

  • Diana Combs Diana Combs on Mar 24, 2015
    Doller General sells a Mold and Mildew Cleaner in a spray bottle.Works fantastic on everything outside.I've used it on sidewalk,patio furniture,siding,just about anything inside and out . Just be sure to rinse well if used on fabric.You'll love it once you get started!

  • GG GG on Mar 24, 2015
    I haven't read all the posts, but would dousing it with clorox and letting it sit a while work? From what I understand, clorox (and I suggest the name brand, because they all AREN'T the same) need to sit for about 10 minutes to fully kill the mold, bacteria, virus, etc.

  • Shari Shari on Mar 24, 2015
    We have the same situation with our daughter's house that has vinyl siding and a trex deck. About this time last year, we used a concentrated product we found at Lowe's called "Wet and Forget." We also used it on the concrete floor of our covered front porch that has a tendency to get black and green algae spots around the parameter. In the past, with pressure washing and/or bleach, the mildew/algae would return quite quickly (usually before the summer was over) but after treating with the Wet and Forget, it is just now showing signs of algae, a year later. If you don't have access to a pressure washer, no problem. The product's website says you don't really even have to scrub, rinse or power wash for the Wet and Forget to be effective; the wind and rain does all the work, but we chose to pressure wash first simply because the mildew/algae was pretty bad and we wanted to "hurry along" the process. Also, with Wet and Forget, you don't have to worry about over-spray killing plants or grass next to the house like with bleach or some other products. I had to laugh because the Wet and Forget bottles had hang tags that very strongly stated you absolutely MUST follow the directions explicitly or you would be wasting your time and money, and then complaining to the company their product "didn't work." Needless to say, we followed the directions to the letter (which was not difficult) and were 100% pleased--pleased enough that we plan to treat everything again with the Wet and Forget within the next couple weeks! Here's the website if you would like to know more about the product:

  • Lee Cunningham Green Lee Cunningham Green on Mar 24, 2015
    Bleach and water 50/50 mix it does work.

  • Phyllis Davis Phyllis Davis on Mar 26, 2015
    Great suggestions but do you know if that takes care of it permanently or do we have to do it often?

  • Connie A Wallis Connie A Wallis on Mar 27, 2015
    We power wash our deck every year but the mold spots don't usually come back in the same spots, this year we didn't have any however I suspect that depends on how much snow/ice build up we have. So I'm not sure how to answer your question about how often it has to be done. So I'm going to say its not permanent, just effective when you have to do it. Good luck and I hope this helps.

  • Lee Cunningham Green Lee Cunningham Green on Mar 27, 2015
    When I lived up north I just did my deck once in the spring and it stayed nice until the leaves fell. So it was once or twice a year,