I have posted this question in another forum, but this forum looked more active, so here goes:

As an admitted novice, I hope to add a small timberframe porch/shed extension to off the back of an existing timberframe ell on my home, circa 1750 (the ell is on a dry stone foundation, as will be the addition). I have desinged the shed adition as a free standing structure, connected to the ell only by side sheathing and rafters. Here's my question -- should I instead connect the frame of the new shed frame to the existing ell frame? I hesitate to do so because I do not want to damage the integrity of the existing frame by adding joinery which was not originally contemplated. Also, although I can easily connect the old and new posts with additional girts, how should I effectively connect the old sills with the new sills so that both structures are essentially one?

Any advice would be greatly appeciated.

Many thanks - Sam Davenport