A friend gave me some jarrah floorboards that had been used as a trapdoor in his 1890's Adelaide (Australia) house. He said that he thought the boards came from that period, they had been the original floorboards in the house. I was intrigued by the grooves that they had on the underside, which are apparently there to stop the nails pushing splinters into the space between the board and the subfloor which it is nailed down to. These splinters can cause squeaky floors (https://www.woodmagazine.com/wood-supplies/lumber/why-do-hardwood-flooring-planks-have-grooves). The boards had three distinct patterns of groove: a single central vee shaped one, two equidistant vees, and a shallow segment of a circle (see my drawing below). I was wondering if the pattern of grooves indicates a date. I have been impressed by the eclectic erudition of responses to many weird and wonderful questions here. Does someone have experience of this sort of thing?
I laid a 3/4" white oak floor with my bro-in-law about 4 yrs ago, all the flooring had 3 or 4 milled grooves underneath but no idea why. I was really just the gopher and old-staples-from-wall-to-wall carpet underlay puller, he did the real work.
You can see they were cut from the same piece of raw wood. You are missing parts that fit together. The wood is lovely.
The drawing is a cross section of the boards, I used CorelDraw, and it has a nice pattern fill option that I used. But you are right, jarrah is a lovely wood.
