Black mold on my deck?

Question

I had it professionally power washed 2 weeks ago and now the black mold spots are returning. What can I use to keep this from happening? It is a red trex deck.

In sun, but extremely wet year,...Oklahoma

Answer 1

Try bleach water to kill the mold off. I used it years ago on black mold on basement walls and it worked very well. It should do the same for your deck but you may have to retreat it ever so often. I am guessing your deck is in a shady and damp area. Am I right?
You might want to see if you can improve air circulation around the deck. You didn't say what the landscaping may be around it? Plants could be causing moisture build up too, causing the mold problem.
Trex deck manufacturers may be able to help with this issue too.

Answer 2

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Answer 3

The black you see is the fruiting bodies of the mold which is in the material of the deck. Washing off the black leaves the 'roots` of the mold in place and the black soon reappears.
You've got to kill off the mold.
Bleach is good, Copper sulphate is better, it is persistant, but it WILL stain blue.
Your local hardware or landscaper may offer a better fungicide choice.
After you kill off the mold, seal the deck.

Answer 4

I have heard that you can use a cup of cholrine bleach in a gallon of water and spray the deck with it.

There are also chemicals that you can buy at home improvement stores that will kill the mold. good luck.

Answer 5

I had the same problem and I used bleach and water. I swabbed it all over the deck then let it dry. All the black spots disappeared and haven't come back. It's been 2 yrs. now. It didn't bleach out the trex either.

Answer 6

They say not to use a pressure washer on a wooden deck surface because it raises the grain of the wood. A Clorox solution is a natural mildew fighter.

Answer 7

One part bleach and two parts water are best. Bleach is the best thing to kill mold. This is what the experts use, just do it yourself instead of paying someone to do it.
Never mix bleach and ammonia. It's toxic and ammonia is useless to kill mold.

Answer 8

Go down to your Lowe's or equivalent homecare center. They have coatings or "paint" specifically designed to address this issue. I believe Thompsons has just such a deck coating.

Answer 9

After brushing it with bleach or power wash, apply with water sealant............. works all the time.

Deck contractor for 19 years.

Answer 10

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get some muriatic acid and mix it about 10 to one and brush it on---it will also kill the grass in walk ways and patios and is very cheap---it is a paint additive. Once it is dry it is harmless. Read the plastic jug it comes in for all the details.