Dating a shed

[Foragefarmer]

I am interested in roughly dating a shed through its construction. Shed is 14' by 16'. Shed was moved in the 1950's so  is on a block foundation. Shed sill is 10" by 10" and hand hewn. I believe the structure was built using scribe rule since I can see marks on the sill corresponding to mortises. For instance a brace mortise is marked with 4 chisel marks two of which are overlaid with bit marks. Another stub mortise is marked with an upside down VII. The other framing is sawn and is only two dimensions. 3x4 and 4x6. So floor joists were 4x6 I believe because you can see the pockets but were replaced with 2x10' at some point. Corner posts are 4x6 mortised and tenoned in with a 3x4 scabbed to it to create an inside corner and pegged to the sill. Braces are 4x6 mortised and tenoned to the sill and corner posts and pegged. There are 3x4 studs 24" on center using stub mortises in the sill and plate. Studs and braces are lap jointed where they intersect. Plates are 4x6. Ceiling joists are 4x6. Rafters are 3x4 with a white oak sapling collar still with the bark on nailed with what looks like forged square nails. I am only relating the parts of the structure that I have seen/can see. 

Any thoughts would be greatly appreciated.

[Don P]

It sounds like what I call transitional. The corners are built up rather than being "guttered" 8x8's with a corner notched out of them, sawn light members with hewed heavy timbers, elements of braced frame construction. I'm going to guess if you pull a nail they are cut rather than forged. Look carefully at it is it cut on 2 sides from a flat plate with a blunt tip, burrs on one face convex on the other from stamping and often split lengthwise, or, forged and drawn from nail rod to a point with a "rose" 4 strike head. That colonial nail and machine saw marks typically do not go together. If vertical sash saw marks and from the framing description it is earlier, maybe turn of the century era, if circular saw marks, around here you're probably getting into the 20's. Pure guess.

[rusticretreater]

Look at the design and composition of the nails used.

[Foragefarmer]

So as far as nails. At some point the shed was used as a smoke house, I don't think that was its original purpose at all. So Interestingly on one side of the rafters are cut square nails and on the other side they added round nails. But the nails used to attach the collars are different from the cut nails. One collar broke at some point; maybe too many hams, and those nails were left in the rafter and the collar nailed above them. The heads are struck and the shaft sure doesn't look cut but they are rusty. I guess I can pull one. 

It is newer than my house. Everything that is original of the framing in my house is hewn. And larger. 12x12 sill, 10x10 corner posts with I guess a 4 inch notch since everything else is 6" thick.

My house is not the original house. The summer kitchen burnt in 1942, but I have a photo from 1931 and it was a 2 room log structure (some clapboard was falling off a corner) with a central chimney. The county historical society says log construction ended in the county in 1765.

[Foragefarmer]

I was wrong. They are cut square nails. 

Not circle sawn. Vertical saw marks on the rafters. 

Another reason why I don't think it was a smoke house to begin with is that there is white paint on the interior of the plate between the ceiling joists. 

[beenthere]

Not circle sawn. Vertical saw marks on the rafters.

Not definitive for aging/dating as sash-gang sawn and band-sawn lumber show vertical saw marks. 
Circular saws found in large mills and small circular mills were abound after the large circular mills changed to large band saws. 

[Foragefarmer]

So I pulled 3 nails out of the rafter and from searching and reading the internet and they look like cut nails with a hand struck head. Burrs are on the same side. Which would put them in 1810's to 30's from what I've read?

They talk about the direction of the iron fibers?

[Foragefarmer]

So I did some further reading and found that you can see which way the fibers run by trying to round the shank over. And the nail broke with a light strike from a framing hammer. So the fibers run across the shank which puts it prior to 1830. So 1810 to 30 and maybe closer to 1810 from the framing details.