I would love to hear about this topic from someone who lives in a timber frame house. I have built one timber frame that I will live in and I am currently going through the painful process of redoing the finish. Buried somewhere in this forum is a post of mine on this topic, so I won't go into all of the same details. To summarize,
I think linseed oil (boiled, raw, or otherwise) is a pretty crappy finish. I have little experience with other "oils" but I speculate they too have some of the downsides of linseed oil, so I am suspect of recommendations of other oils as permanent solutions. Linseed oil offers some level of protection against weather, but it accumulates (magnifies and attracts!) nasty fingerprints and black weathering streaks if the frame is exposed for very long. It would make a pretty lousy finish for a house that you plan to live in. You would not be able to keep it clean... especially with kids in the house.
Polyurethane looks awesome and is incredibly durable. It can be kept clean. If it works on flooring, it will definitely work on timbers. We are sanding most of the linseed oil off of our timbers and applying polyurethane. It doesn't look too bad where we only do a partial sanding before recovering with polyurethane, but it can look splotchy. In some places it is necessary to remove all of the linseed oil to get all of the stain off. But it is not feasible to sand every bit of linseed oil off the entire timber. I'm hoping the splotches will fade. If not, I can live with them, because the timbers look great with poly on them. If you had clean, oiled timbers, you could go over them with polyurethane w/o first sanding. A few of our timbers were clean and we did just that.
The notion that
my timbers will rot from the polyurethane is ludicrous. (your mileage may vary - yes, I've planed timbers that have water coming to the surface, and I wouldn't want to try and seal those timbers at that point. if nothing else, the finish would not adhere well!) Our timbers are on average 3 years old and partially (but not completely) seasoned. They have so many deep checks in their surface, that you could not effectively seal them if you tried.
If I had it to do over, I don't know for sure what I would do.
I would certainly try to permanently enclose the frame sooner. If you thought you could reasonably raise the frame and dry it in within 2 weeks, I would use nothing at all on the timbers... then clean them and polyurethane them once they start checking (6-12 months depending on their initial state?). For prolonged raisings, there seems to be no good answer to a question that badly needs answered.
I haven't been haunting these forums (and probably missed out on a lot of great discussions!) because I've moved on to finishing the house, with the timber framing becoming a cloudy memory. Mostly, I'm doing stonework these days, and my wife is refinishing the timbers. We think we can see the light at the end of the tunnel. And I'm still actively updating my
timberframe blog because there seems to be even less information on how to complete a timber frame than there is on how to raise one!
