Treated Pine Maintenance


Treated Pine is like any other timber product and it must be maintained. Whilst your timber is treated against both rot and insect attack – it is not treated against twisting, ageing, splitting or swelling.

The various chemicals used in Treated Pine, combined with the fast growing nature of the pine species mean that it that is easily affected by temperature, moisture and humidity changes.

There is no guaranteed method to eliminate the nature of Treated Pine to disfigure. However the use of a quality Treated Pine oil, Paint or other Water and UV repellent product will do a great deal to reduce the problem.


Maintenance of all treated pine is particularly important for longevity. The warranties for treated pine no longer exist like years gone by. Some yards may assist you in making a claim, but is generally wiser to oil or paint your timbers to ensure longevity. Also remember that some paints do not breathe and are thus susceptible to locking in any moisture which will rot your timber (particularly in moist areas).

LOSP Treated Pine
Is becoming the most common treatment available. It has a slight solvent smell when fresh and is quite light in colour (although a small amount of green dye is added to the treatment to help with identifying that it is treated)
• LOSP treated pine must be primed with an suitable primer and then have two top coats
• LOSP decking must be OILED with a solvent based decking oil. Do not use water based decking stains. Do not use products such as Flood Spa-N-Deck or Cabots Deck and Exterior Stain without first consulting the manufacturer.

ACQ and MicroPro Treated Pine
Are probably better treatments and dont really need any maintenance. Over time they will of course look ugly if you do not maintain them.
• ACQ Decking – wash decking with a timber cleaner or a mouldicide then let it dry completely for a few days prior to oiling
• Micropro decking – No real need to wash. Just oil it in good fine weather
• Be careful using water based stains. Some water based products will promote and ‘lock in’ mould.

CCA Treated Pine
You probably wont experience any problems using CCA treated pine. It can be painted or stained or oiled with whatever you like.
Possible Problems with WATER BASED stains
• Penetrating types may lock in mould and moisture, which is impossible to remove. If your deck has gone mouldy under the oil or stain then you can try a product such as D-Mould by Preschem. We suggest wetting the timber with water, thoroughly for a day using towels. Then soak some towels in D-Mould and lay them on the deck over the affected area. The D-Mould is attracted to the moisture and will penetrate into the deck. D-Mould is Benzalkonium Chloride with Mono Ethylene Glycol in it, so it is sweet and poisonous = be careful around children and animals.
• Water based stains last longer than an oil but need to be recoated every few years. After a few re-coats your stain will look quite different maybe like a cheap fence paint.
• In areas of high traffic they will wear off and look terrible.
• The only way to remove a water based stain is with a Paint stripper or by sanding

Possible Problems with OIL BASED stains
• Subject to frosting if applied just before very cold weather or a frost
• Subject to frosting is applied just before rain or dew
• Can lock in moisture if applied too thick and hence promote mould
• Wont last as long as Water based and need to be done every year