Identifying problems on exterior timber
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The Most Common Problems with Exterior Timber in Australia — and How to Fix Them
Australia's harsh climate can be tough on exterior timber. From intense UV exposure and heavy rain to humidity, mould, tannins and everyday dirt, timber decks, fences, stairs and cladding can quickly lose their good looks if they are not properly maintained.
The good news is that most exterior timber problems can be managed with the right preparation and protection.
Here are some of the most common problems Australian homeowners experience with exterior timber — and what you can do about them.
1. Timber turns grey and weathered
One of the most noticeable changes to outdoor timber is the gradual loss of its original colour. Sunlight, weather and oxidation break down the timber's surface, producing the familiar silver-grey appearance.
For some homeowners, this natural weathered look is desirable. For others, they want to restore some of the timber's warmth and colour.
The solution
Start by thoroughly cleaning the timber to remove dirt, weathering, surface contaminants and residues. Once the timber is clean and dry, apply a suitable penetrating timber oil.
Equisol Pro E365 Penetrating Timber Oil is designed to penetrate into the timber rather than forming a film on the surface. It contains UV absorbers and can be used clear to allow the timber to continue its natural silvering process, or with an Equisol Colour Tone when you want to retain more colour.
Tip: Don't assume that grey timber needs to be sanded back to new timber. In many cases, proper cleaning followed by appropriate oiling is enough to significantly improve its appearance.
2. Black mould and mildew
Australia's combination of warmth, moisture and humidity provides ideal conditions for mould and mildew. Decks in shaded areas, around swimming pools and in humid coastal environments can be particularly susceptible.
Black spots or patches can make timber look dirty and neglected, but simply applying more oil over the top won't solve the underlying problem. It's also well known that spores live beyond the surface, so any products that get rid of mould only superficially leave the spores behind and your fix is ultimately very short lived. In addition, we advise caution using any bleaching agents on timber as it structurally alters the timber fibres making them weaker and more susceptible to other issues.
The solution
Treat mould before applying an oil or other timber finish.
EQUISOL Null is specifically designed to deal with ingrained mould. It is a biocide formulated to penetrate into the timber and remove ingrained mould.
Once the mould has been treated and the timber has been properly cleaned, it can then be assessed for further preparation and protection.
EQUISOL Pro E365 also contains mould and algae inhibitors to help resist the future growth of black mould on the deck.
3. Dirt, grease and general grime
Exterior timber inevitably gathers dirt over time. Decks are exposed to foot traffic, food and drink spills, garden debris, dust, atmospheric pollution and other contaminants.
A pressure washer can appear to be tempting, but aggressive cleaning can damage the timber surface and leave it rough or uneven. Pressure washing almost always requires sanding afterwards.
The solution
Use a timber-specific cleaner appropriate to the condition of the wood.
We recommend choosing between Equisol Prime and Equisol Vitalise depending on what you are trying to remove. Prime is intended for new or unseasoned timber and for removing old oil coatings and tannins, while Vitalise is designed for dirt, surface contaminants, grease, rust, iron stains and old colour.
Proper preparation helps ensure the next coat of oil can penetrate the timber evenly.
4. Rust and iron stains
Orange, brown or dark stains can sometimes appear around screws, metal furniture, garden equipment or other sources of iron contamination.
These marks can be particularly obvious on lighter-coloured timber.
The solution
Don't simply cover the stains with another coat of oil.
A specialist timber cleaner such as Equisol Vitalise can be used to tackle rust and iron staining.
After treatment, rinse and allow the timber to dry thoroughly before deciding whether further preparation or oiling is required.
5. Old oil and coatings are peeling or patchy
One of the most frustrating deck problems is an uneven, patchy appearance caused by previous film forming coatings.
Some areas may look dark and saturated while others appear dry and faded. You may also see peeling or remnants of an old coating.
To bring your deck back to an attractive and nourished looking surface, it's important not to take short cuts in this instance. You really need to remove all of the old coating, clean the timber and then apply a new protective coating.
The solution
Remove incompatible or deteriorated coatings before applying a new finish.
You will need a high quality professional grade stripper.
EQUISOL Strip has been specifically developed for removing difficult old timber coatings.
Once the old coating has been removed, clean the timber thoroughly and allow it to dry before applying your new protective treatment.
The aim is to create a clean, absorbent surface rather than trapping old coatings underneath the new oil.
6. Timber is splitting, cracking or checking
Small cracks and splits are common in exterior timber, particularly where timber is exposed to repeated cycles of moisture and drying.
UV exposure can accelerate the process by drying the surface, while changes in moisture content cause timber to expand and contract.
Not every crack means the timber needs replacing.
The solution
The best approach is preventative maintenance: keep exterior timber appropriately protected and don't allow it to remain excessively dry and exposed for long periods.
A penetrating oil can help maintain the timber rather than simply creating a film over the surface.
EQUISOL Pro E365 is a non-film-forming penetrating oil that migrates into the timber and is designed to help minimise warping and splitting while providing protection from within.
However, severely damaged, structurally compromised or rotten timber should always be assessed separately. Oil is not a substitute for repairing or replacing structurally damaged timber.
7. Warping and movement
Outdoor timber naturally responds to changes in moisture. Boards can cup, twist or warp, particularly when one side of the timber dries or absorbs moisture differently from the other. We see this happen particularly when timber is newly milled and the exposure to the sun happens on only one side of the board. As the oils naturally evaporate from timber, it's important to be aware of the uneven nature of weathering on new timber. Keep new timber sheltered and refer to your merchants guidelines for weathering time before installation. If you need further information about the causes of this, head over to Australian Treated Pine, who have an excellent article on this topic.
Poor installation, inadequate ventilation and prolonged exposure to moisture can all contribute.
The solution
Purchase your timber from a reliable source who have practiced excellent quality control, stacking and sealing.
A penetrating timber oil such as Pro E365 can help nourish and protect exterior timber while minimising warping and splitting.
For existing warped boards, however, coating alone won't straighten severely distorted timber. Those boards may need mechanical correction or replacement.
8. Uneven colour after oiling
Have you ever oiled a deck only to discover that some boards look darker than others?
Uneven absorption is often caused by differences in timber age, porosity, previous coatings, weathering or inadequate cleaning.
This is why preparation is so important.
The solution
Before recoating, check that the timber has been thoroughly and evenly cleaned.
We recommend a simple test: when the timber is wet, water should distribute evenly across the surface. If some areas repel water while others absorb it, those areas may not be sufficiently clean for recoating.
Once the timber is properly prepared, apply the oil evenly using an appropriate decking brush.
The Perdura Deck Boss Brush is designed specifically for decking and can help achieve even coverage, including between decking boards.
9. Faded colour and loss of the timber's natural appearance
Many Australian hardwoods look spectacular when newly installed, but their colour can fade significantly with exposure to sunlight.
If you want to retain a richer timber appearance, a clear oil may not be enough.
The solution
Consider using a penetrating oil with a colour tone.
Pro E365 can be used with an Equisol Colour Tone to add colour while maintaining the oil's natural, matt appearance.
Explore Colour Tones to find the options available for your project.
10. The biggest mistake: coating timber before preparing it
Perhaps the most common exterior timber maintenance mistake is focusing on the coating rather than the preparation.
If timber is dirty, mouldy, contaminated or covered in remnants of an old coating, applying another layer of oil won't necessarily fix the problem.
In fact, it can lock the problem underneath the new finish.
A better approach
Think of timber maintenance as a three-stage process:
1. Diagnose
Work out whether you're dealing with mould, dirt, tannins, rust, old coatings, weathering or simply fading.
2. Prepare
Use the appropriate DeckMaster preparation products to clean, treat or strip the timber.
3. Protect
Once the timber is clean and properly prepared, apply an appropriate penetrating oil such as Pro E365.
This approach gives you a much better chance of achieving an even, long-lasting result.
Keeping Australian timber looking its best
Exterior timber doesn't have to be difficult to maintain. The key is to understand what is causing the problem before reaching for a product.
For most decks and other exterior timber, a simple maintenance cycle is:
Clean → Treat → Prepare → Oil → Maintain
Regular cleaning and recoating before timber becomes severely weathered can also make future maintenance considerably easier.
DeckMaster supplies professional-grade exterior timber preparation and protection products, including cleaners, strippers, mould treatments, penetrating oils and colour tones. The range is Australian made for Australian conditions and is suitable for both trade and domestic users.