Stair Tall wall

[pdev67]

Happy New Year!
Framer didn't frame the stair tall wall as per design attached, city inspector asked for the letter, can you please advise the solution? Or is it safe?

 

[CANPRO]

How did the framer stray from the design?

I can’t say I’m a huge fan of the framing in your attachment. Looking at wind load applied perpendicular, you have a reciprocal frame.

 

[pdev67]

Reciprocal Frame means?

 

[jayrod12]

It means although its theoretically stable, it's likely too flexible. There was quite the thread on here about reciprocal frames where a bunch if guys posted pics of examples using household items.

 

[MIStructE_IRE]

In terms of its resistance to lateral load, you either have a mechanism there or a reciprocal frame.

If this does in fact work I suspect it will be very ‘flappy!’ and has no redundancy.

You could resolve it by extending the sill trimmer.

 

[CANPRO]

How did the framer alter the wall framing? The contractor should have consulted with the engineer of record before making changes...but if that wall had to be stick framed, I can understand them wanting to alter the framing.

You can google reciprocal framing (the thread referenced by jayrod12 is a good read). Follow the load path for wind applied perpendicular to the wall - it will take you in circles.

 

[pdev67]

I asked the inspector, he said as per design two king studs are shown on the right side of door opening where is only one is installed. Framer said because of dimensions he could not installed two as another perpendicular wall was coming there (see in pictures). Inspector wants to fix it some how? Can we use straps to tie the one king stud with the another stud from the perpendicular wall?

 

[MIStructE_IRE]

I don’t see how that resolves the mechanism in the middle? You could have 10 kingstuds on the right hand side of the doorope and you still have a circular load path in the middle?

 

[pdev67]

I think , In the middle it is laterally supported by staircase midlanding

 

[KootK]

I'm not much bothered by the reciprocal frame business here:

- That's mostly a vibration problem exclusive to floors in my opinion.

- The proportions of this basically make the reciprocation just a moment connection between wall studs with a generous lap.

Obviously, there are things that ought to have been checked about the reciprocation / lap joint.

Can we use straps to tie the one king stud with the another stud from the perpendicular wall

Sure. Although, if you can tie the rightmost stud into the perpendicular wall sheathing somehow, that may be easier. Practically, there really aren't many situations where a stud pack at a framed corner will truly be a "wind post" in any meaningful sense.

 

[OldBldgGuy]

Where are the partitions that frame into this wall? If they are less than 20' apart, it's more efficient to have some horizontal plates for wind bearing at normal stud heights; it's more readily available lumber and more efficient use of it. The partitions then brace the ends of the horizontal beams.

 

[pdev67]

Partition walls are 7'4" apart and there is lateral support form stairs.
OldBldgGuy: Is any additional fixing required at right side of door? It has one cripple and one king stud only where as per design there should be two king studs. Can you please explain little bit of it?

 

[OldBldgGuy]

If the wall is laterally supported by the stairs it might not be a tall wall at all, but your stairs don't show on your drawing. If the partitions are only 7'-4" apart, build the walls just like the rest of the house with the double top plate running through at 8' (or whatever the first floor height is). Frame the 2nd floor wall directly on that double plate, or if you need more lateral support, which I doubt,build a box beam of 2 floor joists to match the floor assembly depth and then frame the upper wall exactly like the rest of the 2nd floor walls. You don't even need the partitions to brace this, the floor assembly will take this little bit of wind loading.