tolerances in frame construction

[Jim_Rogers]

I guess by "belly" you mean sag.

When a beam has deformed over years of load and has began to 'sag', that it has grown a "belly"?

To me a "belly" protrudes out.

I don't recall every seeing a timber grow something that protrudes out, other than branches on the tree when it was alive.

To discuss in timber framing terms one should try and use common terms which mean the direction of the distortion, as with standard lumber.

The grade rule books list definitions of warp, bow, crook, cup and twist. And other defects such as shakes, checks and splits.

A timber framer should understand these terms and how they effect your wood.

[hayton1960]

I was just looking at a back issyue of the tf journal, the one where they describe the repair of charlton court barn. Those 600 year old mortices and tenons were a bit on the sloppy side-1 1/2 " tenons into 1 3/4" mortises, cut up with a spoon bit and twybill (mortice axe) That structure held up a 100+ ton stone roof for all those years It was foundation subsidence that caused the major structural failures.

[Engineer]

I have helped two really talented guys cut and erect two frames in the past six months - my own house, and a 40x40 pavilion for the local Rotary club.   One lays out, one cuts, and five or six helpers and a crane put it up.  So far, every joint, when first put together, has either been a snug push fit or a slight tap or two with a framing mallet.  Pegs are all octagon hickory in drawbores.   You can't put a playing card in ANY of the joints once they have been pegged.    I wish I could have spent more time observing and participating in the layout process.    I have pictures of a couple of frames put together by another local "framer", and they are sloppy to the point of scary.  Some of the joints depend entirely on the strength of the pegs to hold them together - not good.

I'll be doing another frame next year, a 24 x 32 shop and office building, and I hope I can be part of a third frame raising that went together as well as the last two.  The house frame has been up for five months and some of the joints have minor gaps due to drying and shrinkage, but most are still airtight.

[Jim Haslip]

Goos Stuff. Keep it coming.