James,
In response to The Army Aviator: Sodium silicate a.k.a. waterglass might be able to make wood water resistant. I would treat a shingle and then test it with a blow torch.
I am a big proponent of Barricade gel which is the same dry gel which is in baby diapers. (See: http://www.barricadegel.com/ ) It was available in a home protection kit and is probably the next best thing to a house-sized fire shelter but for a much lower price. The only problem is that Barricade needs to be sprayed on around 24 hours before the flames come. Otherwise it will dry out and become less effective. – David