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Question

I am trying to keep the natural colour and look of the sanded Oregon beams I have turned into a 6m dining table. Was wondering what I could use to weather proof the table?

Woodsolutions Answer +

It's hard to keep the natural colour of wood outdoors. A polyurethane varnish would retain the colour best, but varnishes tend to crack and peel under long term weather exposure. A finish that soaks into the wood such as decking oil, rather than one that forms a film on the surface, would be easier to maintain but is likely to darken the wood. We suggest you try decking oil on an offcut, or perhaps on the underside of the table, to test the effect. More detailed information is contained in our Technical Design Guide no. 13 titled Finishing Timber Externally. A copy can be downloaded free of charge from our website here: https://www.woodsolutions.com.au/publications.

Outdoor finishes

Answered on 15-01-2021
Please note that our answer is based on the best advice available at the time. If the National Construction Code, Australian Standards or local requirements have been subsequently amended, our answer may no longer be correct in all details. For more information, please read our disclaimer.

Question

A balcony which had the balustrade and uprights made of cedar rotted in the joints - admittedly the internal faces of the joints weren't painted. What is your opinion regarding pre-primed treated pine? It's (quite) price attractive, but I'm concerned that anything that cuts the surface of the timber will allow decay to start and I'm a bit wary of having to re-treat (with some preservative) every hole and cut, followed by re-priming. The re-treatments all seem to require several hours to dry before they can be primed and some recommend regular re-application which is not feasible.

Woodsolutions Answer +

Cedar usually performs well outdoors, but if water becomes trapped it will shorten its life. Regarding pre-primed treated pine, we assume it is treated with LOSP preservative to H3 level. Re-treating cut ends and notches with a product such as Enseal should be adequate if followed by sealing with a paint system. Agreed, re-application is not feasible. The producers of Enseal advise as follows: All end cuts, rebates, notches et cetera must be resealed with a suitable in-can wood preservative such as Tanalised Enseal for above ground use (H3) and Tanalised Ecoseal for ground contact (H4). A cut end of H5 treated timber must not be put in ground contact. A data sheet produced by Timber Queensland on the use of H3 LOSP-treated timber may be helpful. It can be downloaded here: http://www.timberqueensland.com.au/Docs/Members%20Section/TDS%202016/24_Recommendations-for-use-of-H3_final.pdf.

H3 LOSP

Answered on 10-12-2020
Please note that our answer is based on the best advice available at the time. If the National Construction Code, Australian Standards or local requirements have been subsequently amended, our answer may no longer be correct in all details. For more information, please read our disclaimer.

Question

In what sort of conditions should cuts, drill holes, planed surfaces, etc. of treated pine be re-treated?

Woodsolutions Answer +

The reason for the requirement to re-treat is that treated pine isn't always treated right through the cross-section of the piece. Major breaches of the treatment 'envelope', such as cutting to length, ripping down the middle, etc. can expose an untreated surface. If the timber is located outdoors in the weather, untreated zones may provide an entry point for decay-causing fungi. If treated pine posts are to be cut to length and placed in the ground we recommend placing the uncut end downwards since this will be the more heavily treated end, offering the best protection against wood rot and termite attack. Drilling holes for screws and other fasteners is, of course, unimportant. Treated pine intended for indoor use, eg. termite protected 'Blue Pine', is slightly different in that tests have shown that it retains its termite repellent effect without the need to re-treat cut ends. However, it's recommended to re-treat heavily planed surfaces. These points are explained on the websites of Blue Pine producers.

Treated pine

Answered on 03-11-2020
Please note that our answer is based on the best advice available at the time. If the National Construction Code, Australian Standards or local requirements have been subsequently amended, our answer may no longer be correct in all details. For more information, please read our disclaimer.

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