Wallplate cutting tolerances.

[epsilonGreedy]

My carpenter failed to show at the weekend to prep the wall plate timber for the brickie to bed down.

 

To help get things moving I plan to cut the timber lengths to match the dimensions of the inner block wall (plus 100mm for each half lap). Now I am considering the finer points of the job.

1. I understand the preferred minimum run of a timber section should be 3m or failing that a section should support a minimum of three truss ends. (My wall plate was delivered in 4.8m lengths.)
2. What about an abutment where the wallplate meets a chimney or a single story wallplate butts up to a two story wall. Should I allow for a 5mm expansion gap?
3. In the case of outside hip corners, is a standard half lap joint still recommended? I ask because I saw a video where a 45 degree chunk was lopped off the corner of the wall plate to accommodate the fall of the hip timber.