Does European graded C24 and C30 grade up to Australian standards, if so what grading does it meet ? eg: F5 or MGP10? Do we recognise European Code as EN 14081 as C24 and C30 (which is comparison to the Australian versions of F5 and F8)?
The properties of the European grades can be found in a report online here http://ttps://www.kstr.lth.se/fileadmin/_migrated/content_uploads/Strength_and_stiffness_grading.pdf. The letter 'C' indicates conifer (softwood) while the numbers 24 and 30 indicate the characteristic bending strength in MPa. The properties of the European grades can be compared with the properties of Australian F-grades, as set out in Australian Standard 1720.1, Table H2.1. C24 grade easily matches the strength and stiffness properties of F7 grade, while C30 grade easily matches F8 grade. Ultimately, whether European grades can be applied locally may depend on Australian authorities being satisfied that acceptable quality control processes are in place to achieve these grades. There could also be issues with nail-holding properties in the lower density European species, particularly with respect to truss manufacture and tie-down requirements. Further investigation by an Australian consulting engineer could help to resolve these matters.
Can untreated solid merbau be placed in the ground in an outdoor area e.g. pergola?
Merbau (aka kwila) is a Durability Class 3 timber in the ground, according to Australian Standard 5604, Timber - Natural durability ratings. This implies a probable service life of 5 to 15 years depending on climate and site conditions. In a relatively dry climate, in well-drained soil, the upper end of the range would be achieved and possibly longer. In a wet or tropical climate, and/or in damp boggy soil, its service life would be reduced. You can help to extend the life of the timber with some preservative treatment, eg. No-Rot boron sticks or similar products. You will find information about No-Rot on this website https://preschem.com/products/timber-protection/no-rot.
I am working on a project that has a large external sliding timber door. Door size is 2100w by 3300high. We have found a company that can manufacture this as an aluminium framed door faced with 160mm (approx) wide planks of facing timber on both sides. The door is well protected from rain as it is under a very deep overhang awning but may be subject to late afternoon western sun. We are keen to have a pale timber and the door company suggested New Guinea rosewood might suit. We are concerned that this might not be a sustainable option and someone has now suggested spotted gum. Would this species be suitable for external use - if yes what thickness would the planks need to be if they are 160mm wide and mounted vertically. What treatment would be recommended for the external and internal faces of the door - sealer or oil?
Spotted gum and NG rosewood would both be suitable for an external door, protected from the weather, but neither would be described as particularly "pale" - see colour samples on our website here https://www.woodsolutions.com.au/wood-species-list/Hardwood. We suggest Victorian ash would be a better choice as a pale timber. Presumably the timber facings will be securely fixed to the aluminium frame, so stability will not be an issue and they could be relatively thin, say 19mm. Regarding finishes, we suggest a clear polyurethane on the internal surfaces, and an oil finish on the external surfaces (decking oil, outdoor furniture oil, etc.) An oil finish will have better resistance to sun than a varnish-type finish.