Fixings for Hexagonal Wooden Pool

[Mark]

I'm planning to make a hexagonally shaped outside pool/tank about 2400mm dia (each side 1200mm) x 1250mm high.

The 'Splashpool 400 gallon' below is something like what I'm after, but I want it 500mm higher:

Also, I want it a lot cheaper, and was wondering about the feasibility of making one using 250mm x 28mm decking boards stacked on edge, a plywood base and a lining of butyl. (I reckon that would cost c.£100 in timber or less, if Wickes have one of their periodic '25% off decking' sales in the near future). I think the walls would be strong enough, but am wondering about how to connect the corner joints. I'm thinking of putting a 30 deg mitre on the end of each board then butting them together, and securing with two angled vertical 4" metal strips sandwiched together with bolts at each corner. But I will have to get these made, and I was wondering if anyone has any better ideas using off-the-shelf fixings? Any useful comments would be appreciated!

Best wishes

Mark

[Palindrome]

I would have made each layer from alternate full-length boards and short boards. The next layer up having full-length boards over the short boards, and vice versa.

That would give an overlap to each join below. I would use dowels* in the overlaps, plus staggered dowels in the planks, to tie the whole lot together. No metal strips, screws, nails or glue.

I would probably add one further layer below the (marine) plywood, dowelled through to the layer above. That will raise the plywood above ground level - a few offcuts would be needed under the plywood to support the weight.

I hope that you understand what I mean! Like brickwork, the overlaps will give incredible strength, once tied to the layers above and below.

*For dowels, I would buy hardwood rods and cut to the lengths needed. If you have the patience and an Xacto saw, half a dozen saw cuts along their length will make them easier to drive in.

-- Sue

[Mark]

Thanks for that - I hadn't thought of dowels for the boards which I'll think about; but at the moent I'm more concerned at how to connect the corners of the hexagon?..

Mark

[Palindrome]

On any particular level, the long and the short boards need not be jointed to each other. The long board on the layer above and below totally overlaps the whole length of the short board and the ends of the long board above and below. It is the long boards that are joined to each other, by vertical dowels through the overlaps.

The short boards are pushed tight against the adjacent long boards by water pressure. They don't really need fixings but a few dowels can be added vertically (either from long board above, or into long board below, or both), just to keep them in place.

The corners cannot "open" as the short board will always be pushed out into contact with the long boards and thus close the joints. As the seasons change and all the wood expands and contracts, this manner of construction will keep all the joints tight at all times.

If you are worried about using dowels for this, you could add a steel stud, bolted through from top to bottom of the complete assembly, at each corner. But hardwood dowels is all that is needed.

-- Sue