I made this frame from a plank of wood that has been leaning against my shed in the wind and rain for about 20 years. It came out of the house next door so it could be centuries old. We had a nice hot spell of weather in the summer so the timber got nicely dried out. So I sawed the plank up and gave it a good dowsing with woodworm treatment, although any live worms died out years ago. Despite the nice filigree edges the core of the wood was sound. The rails aren't joined at the corners but screwed to a subframe.