kashew Nov 12, 2013:

A typo? is it meant to be; fasten tHrough header with the lag screw?

Tony M Nov 11, 2013:

Not enough context to be sure, but... 'header' means a horizontal member at the top of something — the horizontal version of a 'montant', if you like! Apart from 'traverse' (= a cross-member generally), I am not personally familiar with other similar terms.

As for 'rough', it's hard to know what they are getting at here; my best guesses would be that it's either something put in place just temporarily, until something else can be finally put in place (but that seems improbable here), or that it is a piece of rough (i.e. sawn, not planed) timber (brut de sciage ?), as it is going to be subsequently clad or otherwise hidden, so doesn't need to have a good finish.