This post was updated on March 1, 2024
Removing Mold and Algae From Decks
Deckstainhelp.com is your number one source for deck staining tips and trends on the internet in 2024. Mold and mildew can be problematic for your wood decks, see below for why this happens and what you can do to prevent it. Leave us a comment if you’ve encountered mold and mildew on wood decks.
Learning your deck has attracted unwanted mold and algae can be disheartening but it is not the end of the world. These contaminants can be removed to reveal a beautiful surface once again. How to remove mold and algae from decks is a common question asked by homeowners. But with the right knowledge, it can be done over a weekend with no problem.
The key to removing mold and algae from decks is using a quality deck cleaner. Deck cleaners are designed to loosen debris like dirt and gray wood fibers and also rid the deck of contaminants like mold and algae. If the proper cleaner is not used then the mold and algae will continue to grow and will reappear in no time. A deep clean is necessary to get to the root of the mold and algae spores. Not only will a good deck cleaner remove these problematic pollutants, it will also help deter them from coming back so quickly. This is especially important if you are staining the deck. Improper cleaning can mean mold and algae get trapped below the new deck stain and begin to eat away at the wood causing rot and decay.
Apply the deck cleaner thoroughly to the surface as directed. Allow the cleaner adequate time to work. Remove the loosened soil and contaminants with a pressure washer or scrub brush. This should remove any mold, algae, mildew, and graying to reveal clean bare wood. Once the mold and algae have been removed from the deck it can then be stained if desired. Certain deck stains can actually help prevent mold and algae from returning so quickly. However, over time if the pollutants reoccur simply wash the deck again in the same manner. Normally every couple of years the deck should be cleaned for maintenance. The key is to not let mold and algae take over but to clean it often enough to prevent it.
New: Best Cleaner for Mold & Alage on Deck Stains
The RAD Guard will remove the black mildew and green algae stains from your wood and deck stains and will prevent them from returning for 1-2 years: RAD Guard Mildew and Algae Cleaner and Preventer
More information on Removing Mold & Mildew on Decks
- How to Clean a Deck Stain From Mold and Mildew
- Mold and Mildew on Wood Decks
- Black Mold and Deck Stains
- How to Remove Mold and Algae From Decks
- Restore-A-Deck Wood Stain Review
The Best Deck Cleaners for Algae Video – DeckStainHelp.com
What to do if you’ve used Rustolem Restore and it’s failing?
Power sand it all off or replace the wood.
How do I remove the mold and mildew off my deck without stripping the actual stain on the wood?
You cannot just remove the mildew without having some or all of the stain come off as well.
Cedar Deck couple weeks old.
Black stains all over. Was coated with Tompson water seal, black spots appier, than sanded and I apply penitrating oil, two weeks later , the same
It is either mildew or rust spots. What did you sand with?
With electric sander that use sanding paper, a part of it i used a planner
You should not have stained the new wood right away. https://www.deckstainhelp.com/staining-a-new-deck/
Looks like rust spots to us. Best to strip off (this will remove it if mildew) what you have on there, brighten the wood (this will remove rust), and then let it sit until next Spring to properly weather. Clean and brighten in the Spring and then stain with a proper penetrating semi-transparent stain: https://www.deckstainhelp.com/best-semi-transparent-deck-stain-reviews-2020/
After neutralizing pt deck, if the wood still has a grayish tint, although much cleaner, is there cause for concern before staining? Thanks.
It should be fine.
After cleaning pt wood I can see green coloring when wet, does this mean it isn’t dead? I am beginnin to think I have better chance of ridding the world of original sin than this green stuff….
It is most likely embedded in the wood and will not come out. It also will not show when stained
Thanks for the quick reply. Any suggestions on the most economical approach to staining spindles? Ever tried using hand spray bottle or is sponge better? If deck stain dries can I reapply if needed?
Spray them and back brush to ensure even application We use pump sprayers.
Help, I need to get the mold or algea out from in between the floor boards on my deck? What do I use?
Not sure what you mean. Please post a picture.
The sides of the wooden planks that you see when you look down.
https://www.deckstainhelp.com/rad-guard-mildew-cleaner-preventer-review/
What deck stain would you recommend for composite decking they all claim to be the best
We have not used a stain on Composite decking in years. We normally just clear seal them. We have used the Defy Composite Sealer and even a concrete water repellent with decent results.
I don’t want to remove my stain. I just want to remove the algae. We stainted our deck just last year.
Try soapy warm water and a soft brush.
Can u stain over the mold
No that is a bad idea.
Is it necessary to scrub each spindle during the cleaning process or just spray w/ cleaner and wash off?
Spray with cleaner and lightly pressure wash off.
What products are best used to clean and stain a boat dock to prevent contamination of lake?
Use the Defy Wood Restoration products for prep and stain.
What if the deck has been stain d and a couple of months later the mold shows up
Now what can be done?
You can try the clean it off with a deck cleaner that contains sodium per carbonate.
Is a 50/50 mix of bleach & water a good algae & mildew remover?
That seems strong. More like one part bleach to 4 parts water.
great summary but why don't you list products that actually work? we bought the recommended deck cleaner at Menard's have been scrubbing for two days, and still there are mildew and algae stains in teh wood. would like to know the names of some products!
We list products on the right that are the top cleaners.