Been asked to make a new oak bench to replace one that has rotted away. I did not make it but have had to try to keep the old one going for the last few years but the rails in the back have started falling out due to the amount of rot in the mortices in the back rail. It's in a very damp location under an oak tree on Dartmoor so want to come up with a design that will not hold water in the joints. The old one has lasted 18 years with regular maintenance which I think is pretty dissapointing