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We have a project that has timber battens/screens on the outside. It is within 5m of the ocean, there is a roof over the batten/screens however it will still have some sun exposure. Our client is extremely worried about durability and maintenance. We have been suggested to use Ironbark with Sikkens

"Here is the process recommended by Sikkens for max outdoor longevity:

1. Surface Preparation
• Ironbark contains natural tannins which need to be extracted prior to coating.
• Use Sikkens Cetol BL Tannin & Oil Remover (Bunnings: $33 for 1L. $92 for 5L) - draws tannins and oils to the timber surface prior to cleaning with Sikkens Ceto BL Deck & Wood Cleaner. Mix with water and scrub into surface. Pressure clean off.
• Use Sikkens Cetol BL Deck & Wood Cleaner (Bunnings: $26 for 1L. $77 for 5L) – to prep for Sikkens timber coatings – apply to timber whilst still wet with mop and use bristled brush to work into timber. Pressure clean off.

2. Protective Coatings
• Apply 1 coat of Sikkens Cetol HLSe (Bunnings: $45 for 1L. $166 for 5L). Traditional oil based, easy maintenance, timber stain for all exterior timber surfaces. A stand alone 3 coat system for the decoration and protection of timber decking, outdoor furniture and roof shingles. It can also be used as a base coat under Sikkens Sikkens Cetol Filter 7 plus.
• Apply 2 coats of Sikkens Cetol Filter 7 plus (Bunnings: $47 for 1L. $180 for 5L). A medium build transparent satin top coat with added UV filters. Designed as the final two finishing coats over Sikkens Cetol HLSe. It remains flexible as timber moves and provides extra protection for timber exposed to maximum weathering."

Considering the close proximity to the salt and the client wants limited maintenance is this the best combination or would you suggest something else.

Woodsolutions Answer +

Ironbark is an excellent choice from a durability point of view as it has a high resistance to wood rot, although if a roof shields the screens from rain presumably the timber won't be wet regularly. Salt air is aggressive to metal so all fasteners will need to be a suitable grade of stainless steel. There might be some salt spray so close to the ocean but it is not particularly harmful to dense hardwoods (think jetties, boats and other seaside structures). The Sikkens specification sounds thorough if somewhat laborious. Your client should seek an estimate from Sikkens as to the estimated life of the finish. A simpler and easier approach would be to apply a reputable brand of decking oil, although it would darken the timber a little. However maintenance would be simpler. 

Finish near sea

In relation to the use of LVL floor joists under "Wet Deck" installations where a waterproof membrane is applied over a compliant cement sheet substrate
AS 4654.2 required substrate materials (which includes the floor joists) to be resistant to moisture damage caused by condensation forming on the underside

My question is LVL resistant to moisture damage over the longer period of time? And is LVL as the supporting floor joists in a Wet Deck situation a satisfactory material for use? My personal preference is for all floor framing supporting wet decks to be treated.


Woodsolutions Answer +

We agree that LVL needs to be preservative treated where it will be under prolonged exposure to moisture. Carter Holt Harvey have a data sheet on their Hyspan LVL, available on the net here: While the data sheet refers specifically to Hyspan, we consider it would apply to other LVL products made from softwood.

LVL weather exposed

I am looking for a type of intumescent coating for the purpose of fire protection for timber materials (structural timber), any recommendation (products or supplier)? I have seen lots of market products for the usage on structural steel, does it generally fit to timber as well?

Woodsolutions Answer +

Wood Solutions has not tested any intumescent coatings but you will find a range of suitable products if you write 'intumescent coatings for timber' or similar wording in your browser. Some products have been tested to establish their suitability for bushfire areas, while others have achieved a specific Fire Resistance Level (FRL) that satisfies National Construction Code requirements. We suggest you contact one of the companies that market intumescent coatings, who should be able to provide relevant test certificates.

Intumescent coatings
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