Improving Top Chord Joinery - Steel Knifes

Howdy!

Ill get right to the point...

Our timber framing operation does not typically get to do traditional joinery. In our part of the country the structural details generally include steel plates. We also end up using all thread / bolts in many cases. Again, this is all following the engineers structural requirements.
We have recently been noticing our top chord joinery (see image below for basic knife plat detail we often use) tends to open up at the bottom once install and under load.
When possible we are going to push harder to use traditional joinery (i.e. running the king post long in-between the top chords and using mortise and tenon and pegs, tongue and fork connection with pegs if no king post), but in the meantime, does anyone have good ideas for keeping out top chord joinery tight? Specific ways to use additional fasteners, how to incorporate traditional concepts into the structurals our needs.

Any help is appreciated!

Hi RLT,

The use of metal brackets in traditional timber-framing is not unknown.

In older frames this is much more likely to be required to repair or strengthen the frame. Later on The Victorians made good use of metal brackets in their building designs e.g. see the attached pic of the old Bradford Wool Hall where ridge brackets not unlike your no3 image have been employed. Unless dry seasoned wood is used you will doubtless get gaps opening up. Structurally these probably don't matter but might not look great.

The best answer to your query is probably to sign up to take a course in timber-framing e.g. as run by Jim Rogers (see below) or Heartwood (TFG).