How to Clean a Deck in NZ: When to DIY and When to Hire Someone
A dirty deck is one of those jobs Kiwi homeowners keep meaning to get to. Between algae, moss, mildew, and general grime built up over a wet winter, decks in NZ take a beating.
The good news is you've got two real options: do it yourself, or bring in a professional.
Here's an honest look at both, so you can decide what's right for your deck.
Can You Clean a Deck Yourself?
Yes, and for a lot of decks, DIY is a perfectly reasonable option. Here's what's actually involved:
Sweep and clear the surface first.
Remove leaves, dirt, and debris so you're not just pushing grime around.
Choose the right cleaning method for your decking material.
Timber decks and composite decking respond differently to cleaning products and pressure. A stiff broom and a deck-specific cleaning solution (not just any household detergent) is the standard starting point.
Diluted oxygen bleach-based cleaners are commonly recommended for timber because they lift grime and kill mould without the harshness of chlorine bleach, which can damage timber fibres and surrounding plants.
Scrub, don't just spray.
Apply the cleaner, let it sit for the time stated on the product, then scrub with a stiff-bristled broom, working with the grain on timber decking.
Rinse thoroughly.
A garden hose is usually enough. If you're using a pressure washer, keep it on a wide, low-pressure setting and never hold the nozzle close to the surface, high pressure can gouge softwood decking and blast right through the protective coating.
Let it dry fully before deciding on any re-sealing or staining.
For a deck that's just mildly dirty and cleaned somewhat regularly, this is a weekend job most homeowners can manage.
When DIY Deck Cleaning Isn't Enough
DIY has real limits, and knowing where they are saves you from making a dirty deck worse.
Heavy moss and algae buildup.
If moss has taken hold, especially on shaded or damp decks common in NZ, a surface scrub often isn't enough to fully remove it, and it tends to regrow quickly if the underlying spores aren't properly treated.
Older or weathered timber.
A pressure washer in inexperienced hands can strip more than dirt. It can damage soft or aged timber, raise the grain, or create an uneven surface that's harder to re-stain evenly afterward.
Composite decking with manufacturer warranty conditions.
Some composite decking warranties specify approved cleaning methods. Using the wrong pressure or chemical can technically void a warranty, worth checking before reaching for a pressure washer.
Large decks or multi-level decks.
What's a manageable weekend job on a small deck becomes a multi-day slog on a large wraparound deck, and consistency across a bigger surface is harder to maintain by hand.
You just don't want to.
Sometimes the honest answer is: it's a doable job, but not one you feel like doing. That's a legitimate reason to hire someone too.
Why Professional Deck Cleaning Gets a Better Result
A professional deck cleaning service isn't just paying someone else to do the scrubbing, it typically achieves a genuinely different result for a few reasons:
Correct pressure and technique for the material.
Professionals calibrate pressure washing equipment to the specific decking material, avoiding the gouging or grain-raising that happens with a consumer pressure washer on the wrong setting.
Proper treatment of moss and algae at the source,
not just surface removal, which means the deck stays clean for longer rather than the growth returning within weeks.
Consistent results across the whole deck,
including hard-to-reach edges, joints, and gaps between boards where grime tends to build up and DIY scrubbing often misses.
Get Your Deck Professionally Cleaned
If your deck has heavy moss, algae, or grime that a scrub and hose haven't fixed, or you'd simply rather not spend a weekend on it, get in touch with Squeegee Boys for a deck cleaning quote.