Expert Secrets… Remove Mold and Get Green Algae off Your Deck…

September 8, 2023
Deck cleaning | By Jason Rowe
remove mold from deck

If you want to know how to remove mold from a deck…

If your deck is covered in an unsightly green growth, then you need to know how to get green algae off your decking and eliminate that wretched mould once and for all!

Lucky for you, this guide will show you everything you need to know…

Let’s get into it…

Removing green algae and mold from your deck is actually really easy…

And when I say easy, I mean really easy…

All you need is a pressure washer set on a low setting and voila!!

That ugly green algae will come straight off…

It’s true…

If you have a pressure washer and you know how to clean your deck with it, then that’s all you need to remove mold from a deck…

That’s it!

Problem solved!!

Let’s move onto the next problem…

Hold on, hold on…

Not so fast!!

There’s a rumour that mould spores can embed themselves into the grain of your timber decking and grow back with a vengeance the moment you finish pressure washing your deck…

So what that means is, a pressure washer can remove green from your decking and it will look all squeaky clean, but…

That conniving mould will sit there in hiding and rear its ugly head the moment you think you’ve beaten it…

The moment you turn your back, that green mould will spread across your deck like wildfire…

So what I’m saying is, you can’t just use a pressure cleaner if you truly want to remove mold from your deck…

There’s a few other things you need to do to win this battle…

Don’t worry, I’ve got you…

Here’s your step by step battle plan…

Hey! Do you have a question?

I know you’re busy reading all about getting mold and algae off your deck, but if there’s something you’re struggling to find answers for, why don’t you just ask me?

Yep, I can be your personal deck consultant…

How to remove mould and green algae from a decking, step by step…

What follows is a simple 3 step plan to remove mold and algae from your deck for good…

As you’ll see, it’s “oh so simple” so there’s nothing to worry about…

Ok, let’s start with the basics…

1. Remove leaves and debris from your deck…

I like to do this one with a leaf blower but you can also do this with a broom…

Walk around your deck and blow off all of the leaves, sticks and bark…

Just remove anything that sits on your deck…

See, all that rubbish on your deck is one of the main reasons you have mold growing in the first place…

All of that debris keeps your deck damp…

Dampness leads to slimy algae and green mold to spread across your decking…

So get all that rubbish off and you’ll be eliminating the dampness…

Make sense?

Besides, it’s impossible to scrub a deck with all those leaves and gunk on there so sweep it all off..

Ok, that’s the very complicated step 1…

Let’s go to step 2…

2. Scrub your deck with a mould remover…

Like I said before, if you try to blast that mold off with a pressure washer, it’ll give you the false sense of victory…

All of the green algae and mould will look like it’s gone but those pesky mold spores can be embedded into your wood deck…

And you already know they’re coming back with vengeance…

That’s why we have to kill ‘em off and not just clean them off…

Let me introduce you to the concept of a mould killer…

This is a fancy little cleaning product that you scrub into your decking and it kills the mould so it won’t grow back..

Great idea, hey?

All you do is scrub it onto your deck and let it sit for 15 minutes…

Then you move onto step 3…

3. Pressure wash your decking…

Now this is easily the most enjoyable part of the process…

Blasting that green slime off your deck like you’re one of the Ghostbusters is more fun than you’ve had in a while…

Believe me…

Just remember to never cross your stream…

Anyway, back to reality…

Using a pressure washer is really simple…

You wanna keep the tip about 30 cm away from the surface and work up and down along the boards until all of that green algae and mold is gone…

And you want to make sure that you use a low pressure setting…

If you’re using an electric pressure washer, then make sure you use a fan tip and not a tornado tip…

Your fan tip will look like this…

Remove mold from a deck with a fan tip

This is good…

A tornado tip looks like this…

Don’t remove mold from a deck with a tornado head…

This is bad…

The Tornado tip is meant for heavy duty pressure washing and will probably be a little too harsh for your decking…

So stick with the fan tip…

Now if you’re using a bigger beast like a petrol pressure washer you’ll want to pay attention…

Make sure you use the 40 degree tip which is the white tip…

40 degree fan tip to remove mould from deck

This will give you a nice fan tip that won’t blast chunks out of your deck…

Just remember to keep the tip about 30 cm from the surface of your deck and work up and down the boards, not across…

If you want a full breakdown of so you don’t mess this up. then you can check out my Homeowners guide on how to pressure wash a deck

Either way, that’s the 3 step process to removing mold and green algae from a deck…

If you’re pretty comfortable using a pressure washer then let’s look at which mould remover you should use…

Which Mold Remover Should you use?

Ok, this is a hotly debated topic…

Some people say you should use hydrogen peroxide and mix it up yourself…

Others say you should grab some white vinegar, dilute it with water and spray that onto your deck…

Then there’s the “Never use bleach” preachers…

The thing with removing mould from a deck is that the surface is made from wood so you have to treat it differently from your bathroom mould…

If you use a bleach that you use in your bathroom, you could potentially destroy your decking…

You see, after you remove the mould and algae, you’re gonna want to stain your deck or if your deck is already stained, you want your deck to look brand new…

So you want the mold gone but you also want your deck to be in the best condition to absorb the deck stain…

And you definitely don’t want your mould killing treatment to damage your precious deck in any way, right?

That’s why the better option for removing mould from a deck would have to be an oxygenated deck cleaner

That is any deck cleaner that contains sodium percarbonate…

Just to make this easier on you, here’s a few deck cleaners that you can use…

Defy Deck cleaner

Restore-A-Deck Deck Cleaner

Cabots Deck Cleaner

Intergrain Deck Prep Mould Killer

There’s so many more out there, but these are some of the better ones on the market…

While I do recommend buying a deck cleaner that is designed specifically for a wood deck, making your own is still a great option…

How to make your own mold and algae remover…

The three home made options that I love are the white vinegar mix, the hydrogen peroxide mix and the Napisan or OxiClean mix…

You know the professional deck cleaners that I just mentioned in the last section, well they contain sodium percarbonate…

And sodium percarbonate is sodium carbonate mixed with hydrogen peroxide

So I think we might be onto something by using hydrogen peroxide…

What do you think?

And you may not know this but, Napisan and Oxiclean contain sodium percarbonate…

Fancy that…

Let me show you how to use these household products as a mould killer on your deck…

How to remove mold from a deck with Vinegar…

I’ma just break this down step by step…

  1. Start by mixing up a half cup of white vinegar to 1 gallon of clean water into a bucket and add a squirt of dish washing liquid…
  2. Remove any furniture and debris from from your deck…
  3. Water down all plants and grass that could be harmed by the vinegar mix…
  4. Use a deck scrub brush to scrub the vinegar mix into your deck…
  5. Allow it to sit for 15 minutes but keep the surface of your deck damp…
  6. Pressure wash vinegar from decking…

That’s pretty much all you need to do…

If you feel your vinegar mix isn’t strong enough, you can increase the strength by mixing 1 cup of vinegar to 1 gallon of water and give your deck another scrub…

Then repeat the steps above…

How to use Napisan or Oxiclean to remove green algae and mould off a deck…

Napsiana and OxiClean are great options because they contain sodium percarbonate which is the same ingredient that is in the professional deck cleaners…

Plus It’s really easy to mix up and safe to use…Here’s what you need to do…

  1. All you need to do to remove mould and algae with OxiClean or Napisan is to add 1 cup to 1 gallon of hot water and then mix it through until it dissolves…
  1. Next you want to grab your deck scrub brush and scrub the mixture onto the surface of your deck…
  1. The Napisan or Oxiclean mix needs to stay on the surface for at least 15 minutes. But make sure that the mixture doesn’t dry up on the surface. If it starts to dry, scrub that section with some more of your Napisan mixture…
  1. Once the 15 minutes is up, pressure wash or hose your decking off…
  1. Clean your deck with a deck brightener

See…

Easy peasy…

What I’ve just laid out for you is like a cheat code for getting rid of that ugly green mold…

No fancy schmancy deck cleaning chemicals, just cheap products you probably have laying around your home somewhere…

But let me get one thing clear…

I never clean a deck in this way…

I always use professional deck cleaners

I believe wholeheartedly that they are superior and completely necessary

But, the choice is yours…

If you want to be like Macgyver and whip up a mould remover from the products laying around your home…

Hey, why not?

Let’s keep things exciting…

Just don’t blow anything up…

Otherwise, be like “boring old me” and invest in professional products…

Either way, one thing’s for sure…

Once you’ve removed that green, you really want to keep it off…

How to keep mould and algae from coming back…

This is really not hard to do…

It does require you to NOT be lazy, so it could possibly be completely impossible for some people…

Not pointing fingers…

Just saying…

Anyway, here’s what you need to do…

  1. Keep your deck clean…

That’s it…

Mold and algae start to grow when you have a damp and dark surface…

So if you let your deck sit there with water on it and it’s in the shade or you have leaves and debris sitting on it, you’ll have mold growing on it again in no time…

So all you really need to do is sweep your deck off once in a while…

And maybe even give it a scrub and clean every couple of months with a soapy solution…

It really is that easy…

Also, you might want to think about switching your oil based deck stain over to one of the better water based deck stains

Oil based stains are more susceptible to mould and algae than water based deck stains are…

So if you have a reoccurring problem, maybe you should consider he switch…

And that’s about all I have to say on the matter…

So I’m gonna wrap it up right here…

If you have any questions, leave me a comment below and I’ll do my best to get back to you with an answer…

Peace, 

Jason…

Need some Expert Advice?

I’ve got 10 years of deck knowledge crammed into my noggin. I can pretty much guarantee I’ve got an answer to your problem just rattling around in there…

FAQ’s

What is the best product to remove mold from a deck?

The best product to remove mold from a deck would have to be a sodium percarbonate based deck cleaner. These oxygen bleach based cleaners have been specifically made for deck cleaning. They remove mold from a deck without causing damage…

Will vinegar kill mold on deck?

Yes, vinegar will kill mold on a deck. You can mix it with hot water then spray or scrub it into your decking. This will remove any mold or green algae on your decking…

How do I keep my deck mold free?

The easiest way to keep your deck mold free is to make sure you regularly sweep any debris from your deck and then scrub and clean it at least 3 times a year.

Summary
Expert Secrets… Remove Mold and Get Green Algae off Your Deck
Article Name
Expert Secrets… Remove Mold and Get Green Algae off Your Deck
Description
If you want to know how to remove mold and get green algae off your deck, then this guide will show you step by step…
Author
Publisher Name
The Deck Restoration Co.
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2 Comments

  1. David

    Very helpful tips. All of your articles are very helpful and easy to follow. I like how you anticipate my questions and provide the answers in a detailed manner. Thank you for that. I appreciate it.

    • Jason

      You’re very welcome. Thanks David