I have found a better product than sikens for various outdoor uses on wood. It's called Trusealer, a water based product that forms a flexible plastic like membrane on wood surfaces(and other surfaces as well according to the manufacturer). It's a clear product that you spray on with a garden sprayer or you can brush or roll it. It formed an awesome water repellant layer that they guarantee for 5 years. Great product. About the same price as sikens products, which I have tried in the past, but without the smell they have and the fuss and mess.