Hi Mike,

The difference between scibe and square rule framing in a nutshell is standardization of building components to fit the particular building pattern. The easiest way to tell is to look for markings (carpenter's marks) at the joints that often look like (or are) Roman Numerals. If the frame has them, it's probably completely or partially scribe rule. I just looked at a frame today at an old grist mill in Yellow Springs Ohio that has scibe rule markings but also has square rule type housings in the roof system. Probably built by someone who learned to frame scribe, but was learning square.

The reason for the carpenters marks is to make sure each piece in the frame goes back exactly where it was scribed to fit. Consequently, you don't need to mark the pieces as you take the frame apart since they already are. You do need to make (or hire someone to) very good frame drawings and put all the marks you find on them as you take everything apart. Make sure to put the marks on the drawings where they are on each piece in the frame.

If the frame has no marks, it's probably square or mill rule. In that case you need to mark or tag the timbers as you go. We use a simple system that looks at the frame in plan view. The posts are usually in rows in two directions. They are lined up within the bents, and most often lined up across the bents too. Once you have a plan view of the post feet, you can identify the bents from left to right as Roman numerals and top to bottom with letters of the alphabet. Each post ends up with an alphanumeric ID like IA, IIC or VIB. For the most part, that's all you need since the walls girts, rafters, braces etc. are all the same within the pattern. If you need to add a third dimension, we use English numbers so a low wall girt might be IIA1 while the one above it is IIA2.

Clear as mud? It all makes sense when you do it.

Hope this helps.

Rudy