Unfortunately we are not aware of anyone stocking or producing the textured hardboard shown in your photo. Hardboard is not MDF, it's a sheet product known in earlier times as Masonite. It is now produced in a Standard Grade and a "tempered" version, but not with an overlay as far as we are aware, more info via this link https://plywoodaustralia.com.au/hardboard/. Hardboard is also produced as an external cladding material under the brand-name Weathertex.

American red oak was not included in Warringtonfire's tests on wall and ceiling linings, only American white oak as per our Regulatory Information Report RIR 45980.10. However, red oak has been confirmed as a Group 3 material in a separate report which we will send direct to your email. 

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.

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. 

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.

The span tables in AS 1684.2, Residential timber-framed construction, assume an upper storey floor load of 40 kg/m². However, various software programs allow you to input different floor loads.

We were pleased to hear of your very practical hands-on project. No doubt you will be using some kind of hardwood for your coffee table. With regard to sustainability, our Environmental Product Declarations (EPD's) provide helpful data. You can download them from our website via this link https://www.woodsolutions.com.au/resources/publications/environmental-product-declarations.