Interesting flooring to joist detail

I was helping my boss clean out his basement this afternoon, and noticed an interesting flooring detail. I have seen many floor boards that have been adzed for proper thickness over the floor joist. These floor boards had been shiplapped, and on the underside of the shiplap, they had put a 1/2" wide rabbet down to an even thickness. It was only about 1/16" to 1/8", depending on the flooring deviation. They then used this as a guide for the adze work. Kind of a neat approach. Has anyone else seen this?


Dave

This is a standard detail in eighteenth and nineteenth century softwood flooring, here in the Uk.
Ged Gardiner wrote a fascinating article for the Georgian Society, in which he dismissed the currently accepted theory; the rebate was made with a sash fillester plane, ( as described by Walter Rose, in the Village Carpenter). Instead he postulated that the rebate was made using a standing fillister, or a rebate plane with a depth gauge, ( the depth being gauged off the visible face of the floorboard). In practice, the carpenter would lay the floorboards face down on a flat plank, then plane from above until the depth stop made contact with the flat plank, and the rebate on the floorboard would now be cut to a standard depth. Then using a hachett or an adze the waste could be removed to this depth, once the position of the joists were known.
Hope you can follow this.

Thanks, Sussexoak. That makes sense to me. This frame is c.1830 square rule. I haven't gotten much of a chance to study the frame, as most of it is covered over. However, I got a small glimpse of it in the bathroom we are renovating. I can't see all of the beam, but it's big, and has 2 3/4" mortises, which is kind of odd. The house next door that I'm gutting is also c.1830, I haven't seen the same flooring detail, but I've got more ceiling to pull down, so I'll be keeping an eye out for that. The scantlings for both are up and down sawmill, and the rest is hewn. There must have been a sash saw somewhere around here, as I've seen many up and down members in buildings around here, including my horse barn.


Dave

Dave --

I recently saw this detail for the first time on a ca 1814 scribed house frame in Morgan County, Ga -- about 15 miles from here.

As a side note, this would have been one of the very first houses in the area and it was very well built -- not the usual frontier rush job. The sills of this house featured the cleanest and best hewing I have ever seen. So clean, I was blown away. I hope to go back when I have more time and do a proper job of surveying it.

Gabel