I’ve just discovered this rather lengthy document and thought it might benefit some forum members.
This no longer seems to be working on my machine, @Tim_Gilbert, but perhaps it is just my system which is faulty.
I have tried the link myself and unfortunately it no longer works. I have looked for an active link. Try
The original post is too old for me to edit.
Edit: This is not a like for like substitution. The original post was for traditional buildings but the replacement is for historic buildings. I included it as it was all I could find at the time and it still held pertinent information.
I came across this today:
A new link for traditional buildings:
I would also recommend this book from the Society for the Protection of Ancient Buidings. A good read.