I decided on a square pier mainly for ease of obtaining formwork materials, but would have been just as happy with a round section. Handy sized pine boards through the hardware measured at 290mmx1500mm, which was exactly what was needed for a 250mm square pier. All that was needed was to rip two of these down to 250mm width, nail tri-quad onto the wider pieces, then screw it all together, the inside coated with motor oil pre-assembly. As it turns out - this was not the best approach.... after the pier formwork was filled - one of the boards cracked through a knot. If I were to use this timber again for this purpose, I would reinforce it more with framing timber, or else use similarly reinforced heavy plywood. The crack was minor, but could have been nasty...

The footing for the pier is 600mm (2') cubic, of reinforced concrete, with this and the pier itself being poured as a monolith. Reinforcing rods extend from the top of the pier to the base of the footing. A concrete mixer was used to prepare concrete from pre-mix in bags (36 bags total) - extra cement (2kg cement per 20kg bag of concrete) was added to produce a higher compressive strength mix - approx 32MPa. The height of the pier was chosen to be 1.5m above ground level - this allows for a pier height above floor in the obs of approx 1.2m. The pier plate was made by a local plate profiling company from 10mm mild steel, cut into a round corner 250mm square. Four 1/2" holes were drilled to take the four 500mm lengths of 12mm stainless steel threaded rod set into the pier. The formwork was removed 36 hours later, and then the pier wrapped in plastic and watered 2-3 times per day for a week to help the curing process.
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