Hi. I've had some old oak beams out in the garden for the best part of a year while my house was being renovated. I'd like to bring some of them inside to use in consttructing a bookcase. Obviously they've been exposed to a lot of rain, bugs etc. Is it going to be possible to use them and if so how should I prep them and how long before I could actually use them? Haven't a clue! Thanks for any advice.