Replacing a brace in a mortise and tenon building.

[leeroyjd]

Is it possible to replace a broken or missing brace?
We have an old barn that had one missing for years. It now has a brace but it's just a 45 that's been nailed.
Seems like if I make the tenons shorter than the mortise depth, I may be able to do this.

[Don P]

The only way I can envision that working is if one end is normal and the other has a loose tenon in a long bridle notch in the brace, then peg at least twice through the bridle and long loose tenon.

[Ljohnsaw]

Or maybe a two piece brace that has a center lap joint that is more of an angle.

[D L Bahler]

I have seen it done, where in order to replace a lost or broken brace one of the mortises is elongated so that a replacement brace with tenons like those on the original can be "swung" in place, and then a piece of dense wood is inserted into the hole below the new brace and pegged in place. 

[Heartwood]

Like D L Bahler says; from Historic American Timber Joinery, by Jack Sobon:


 

[Tom King]

I've done it in old house frames by putting wedges in the mortises where the long points of the tenons would go.  The tenons can't be perpendicular to the timber that the mortises are in, or you can't get it in there.

I make a full sized drawing (can just be on sheets of plywood) to size the wedges, and the brace.  The outside ends of the tenons have to be parallel if you want it to be tight when you get it in place, and want to stay in place.

It will still serve it's function fine, since it's in compression.

You can fit the lower tenon, and shape the top one so it will go in under the filler.   The full sized drawing can show you what will work.

[VictorH]

I would prefer one or two of the options already mentioned.  Another option would be to open up the mortise on the post and make a brace that is tenoned on one side and "let in" on the post.  The Tenon would need to be tapered a little so it will allow the brace to swing into place.