Composite Deck Materials used for Deck Surfaces, Railing, Balusters and Steps have been in use for more then 15 years in the United States and although they are low care product they are not maintenance free.
Because composite materials use a high content of plastics they are less prone to absorb water. Wood decking that is pressure treated has a chemical injected in it that treats the wood to reduce its breakdown when molds, fungus and bacterial enter it.
Eventually all materials will breakdown you simply have to look at historic buildings to understand this. Even ancient temples made of stone erode and any wood or metals used in their construction will long be gone before the stone structure deteriorates.
I guess if you wanted a deck that would last a hundred years then your best bet would probably be stone. But unfortunately they don’t make decking material out of stone.
However even if you used Stone you would still need to clean the surface from time to time.
Consider this how often do you need to bleach and clean your bathtub mat? For most of us it is once a week or every other week. With this understanding you can see that even mold resistant materials need care.
Removing Mold from Composite Decking
Since mold is all around us and all it needs is a little moisture to start growing it is likely that you will get surface mold on your composite deck. You will also likely get dirt and bird droppings that also need to be removed.
For best results treating of any surface to remove mold requires saturation in bleach. You will find that most products that are made specifically for exterior cleaning of mold contain bleach and you can save yourself a lot of money simply by using the household bleach that you use for your wash and cleaning the bathroom.
When you treat the surface you want to keep it wet for a minimum of 15 minutes to an optimal 30 minutes. This means you keep a small amount of liquid on it at all times by respraying the surface and applying more bleach.
If you under treat the area you might as well have not even attempted it.
Tools you will need to remove Deck Mold
You will need about a gallon of bleach for a 10×10 deck.
To apply the bleach you should purchase an pesticide pump up sprayer available at most supply centers for about $15. You do not need the best one but a 2 gallon tank will mean you have to refill it less often.
A nylon push broom with soft bristles or a boat brush that connects to an extension pole will be used for scrubbing surface dirt after the bleaching process. If you don’t have one then a standard broom will do if it has nylon bristles not straw (natural fiber).
You will need about 2 cups of household clothes detergent.
A large 5 gallon bucket or large enough for the broom head to fit.
Garden hose with a spray head that has a strong stream and rainfall setting.
Cleaning the Deck of Mold
The best time to do the work is when you will have a few hours of no direct sun. So depending on the position of your house early morning or late in the day is best.
Start by testing your pump sprayer. Fill it with some plain water and make sure you know how it works. You can actually pump a lot of pressure into it without damaging it and it will give you much more spray time.
Fill your 5 gallon bucket with your bleach. Since bleach is now sold in less then a gallon bottles don’t worry about getting an exact gallon.
Now add water to your bucket to bring the level up to a few inches below the rim.
This will be your working solution and you will find that you use about the same amount to cover your deck as you will to spray your balusters and steps.
You want to start against your house and work at the area farthest from your deck steps. Eventually you will work your way down the steps and off the deck.
As you work you want to spray the top surfaces and insides of your deck railings. Make sure you get the surfaces under the railings
Once the whole deck is wet you can begin working on the outside railings and any decorative wrap around material under your deck.
As you complete the outside remember to look up on your deck to see if any areas are drying. You want to keep them wet.
When you are down to your last batch of solution you want to go over any areas that need special attention. Usually the pathways where you walk need extra help.
Final Cleaning
You will want to remove the bleach after it sits for about 30 minutes. This is a good time to give your deck a wash with soapy water.
Use your clothes washing detergent by placing it in a bucket then applying it with your deck scrubber or broom.
Make sure that you cover all the areas that need extra help especially walking paths and your steps.
Once the surface is clean use your hose to remove the bleach and soap.
When you see that the soap is no longer sudsing on your deck you have removed most of the bleach too.
Over the next day your deck will continue to show improvement as it drys but you may need to complete the process again to get the best results.
Final Note
Although the area is larger then your bathroom it really shouldn’t take you more then about an hour or so to complete. You will get faster at it the second time you do it and you may find that mixing your bleach solution directly in your sprayer is easier.
However for the first time you want to mix it in your bucket so you make sure you cut the bleach accurately and don’t have half the deck treated with strong bleach solution and the rest treated with mostly water.
I STRONGLY suggest that you wear old clothes that you could even throw away because bleach will ruin your clothes. This goes for your shoes too.. You can be as careful as possible and you will still have bleach spots on your tshirts.. I always do and I have done this many many times.
This process should only be needed once or twice a year at most unless you live in a very humid area like Hawaii or South Florida.