Timber is relatively unaffected in a salt-laden environment, hence the number of structures in coastal areas which are traditionally made from timber (jetties, boardwalks, steps down to the beach, etc.) One type of degradation that has been observed in coastal areas is "defibration", explained in a US Forest Products data sheet that can be accessed via this link https://www.fpl.fs.usda.gov/documnts/techline/Techline_06-2011-001.pdf. Defibration has been observed adjacent to Sydney beaches in unsarked roof spaces where salt-laden air can enter, becoming absorbed by uncoated softwoods such as oregon. However, it progresses very slowly, and simply causes a woolly, stringy surface. Presumably your sub-floor timbers will be hardwood, which is not affected due to its greater density. No doubt the external cladding and decking will have some kind of coating eg. decking oil. Internal timber framing is unlikely to be affected in any way. Framing for external decking could be hardwood, or treated softwood with a coat of decking oil. Note that many coastal boardwalks are built from treated pine with satisfactory results, and the defibration issue should not be over-emphasised. All metal fasteners, or course, need to be corrosion resistant, preferably stainless steel.
What is the standard or recommended tongue thickness for 19 mm Tasmanian Oak floorboards?
According to Australian Standard 2796, Timber-Hardwood-Sawn and milled products, Part 1: Product Specification, the tongue thickness for 19 mm hardwood strip flooring should be 6.0 mm for face nailed, double-dressed, off-centre milled boards, or 6.5 mm for face nailed, double-dressed, centre milled boards. The corresponding groove dimension should be 0.5 mm greater to allow entry of the tongue.
I have a pole house 35 years old. The previous owner was careless with the protection of the poles where they entered the concrete base. I have drained and cleaned all the poles where they enter the concrete over the last 7 years and the poles look good at where they enter the concrete. Wanting to spend considerable money on the new kitchen and flooring I was hoping that there was a NDT to ascertain the condition of the poles in the concrete. There is some typical movement in the house and additional bracing has been added.. Having spoken to a few building inspectors gives me little comfort as their comments seem to amount to “ I just look at the poles and if they look OK, that’s all I do”. I was wondering if there is a way of determining the condition of the pole in the concrete. They may look good entering the concrete but it’s what you can't see that worries me.. The house is located on the western side of Lake Macquarie (Rathmines).
It is unfortunate that the owner didn't keep a record of the type of treatment carried out on your house poles, but presumably it was a process that complied with the Australian Standard. Make sure stormwater does not discharge adjacent to the poles, particularly those around the perimeter of the house. Internal poles are generally in relatively dry ground. A simple test suggested on a US website is as follows: "Checking the pole at ground level should be done using a screwdriver with a 12-inch shank. Hammer the screwdriver 6 inches below ground level on the high side of the pole. If it is rotten, the rotting most likely will be on the side of the pole where the dirt level is highest". This test refers to stand-alone power poles directly in the ground and might not be possible for poles set in concrete. If you are unable to access the ground line zone for inspection you might achieve peace of mind by providing some supplementary treatment. For example, Polesaver Rods, as used in the maintenance of Australian power poles, could be installed, more info on this website https://preschem.com/products/wood-pole-preservatives/polesaver-rods/.
