Cracks from knock through (threads have been merged)

[John Wardle]

Hi getting some hairline cracking in these areas from a rsj I've had installed under this wall . Wondering is this supposed to be expected a bit. Blue lines are where cracking is

 

[John Wardle]

It is a internal knock through for kitchen diner

 

[tony1851]

The cracking can be caused by insufficient packing, or possibly even by deflection (bend) of the beam - all beams deflect to a greater or lesser extent.
Unlike the old soft lime plasters, hard gypsum skim coat is very unforgiving.

Did you have a steel post originally supporting the outer end of the beam? The cracking pattern upstairs suggests that the post may have settled on its foundation. If the beam is now supported directly off the inner skin of the wall, that should be sufficient support.

It's not surprising that you have a few cracks above, considering the work that has been done on that part of the house. Maybe just leave the cracks for the time being and if they don't get any bigger, just cut out and fill, and ease any window casement which might be sticking.

 

[John Wardle]

Hi Tony
Yes that was vertical post end. Which is now in the wall. I've noticed that the outside seems to have vertical crack in the render the opposite side to the corner window crack on the picture