I'm using Barrettine Wood Protective Treatment on my stables and shelters, safe for plants and animals once dry, dries quickly (although that maybe because it's the first time I've treated my 3 year old stables!) and low odour. Very pleased so far.
Ronseal shed and fence preserver. It’s a traditional solvent based product, not a water based one, so it penetrates better and lasts longer than a water based treatment.