We are removing a couple of load bearing walls as part of renos in our home. The engineer specified a W8x21steel beam to replace the load bearing wall. The floor joists are 2×10. The joists are 2×10 and W Spruce. Their span is about 12' and are spaced 16" on center.
The space above the joists is comprised of two bedrooms and 2 bathrooms (shower in one and tub in the other). The upper area is being renovated and bedrooms will have hardwood flooring (carpet previously) and tile in bathrooms.
The contractor had originally put the bolts too close to the joists and ended up cutting some of the LUS210Z hangers to make them fit. Our engineer has since asked the contractor to move the bolt locations so that they no longer interfere with new hangers.
For the hangers the engineer has directed the contractor to use LRU28 hangers instead. We also checked with Simpson and they confirmed that LRU28 can be used but recommend that we use SD10x1½” screws into the face flanges and SD10x2½” screws through the double shear joist fasteners.
Questions:
As it turns out several of the joists are not sitting flush with the beam and have as much as a 1/2" gap at the top and 1/4" gap at the bottom between end of joist and steel beam.
We checked again with Simpson – they advised that they have test results with short cut joists for LUS hangers but not with LRU ones. They checked the test results and advised that even with the bottom two nails not really going into the header and short cut joists the LUS hangers would be fine when installed with SD9x2 ½ (SD9212) screws (as long as they are not cut of course). They are unable to comment on the LRU hangers as they don't have test results with short cut joists. To sum it up they recommend using the LUS for that reason but say ultimately it's the engineer's decision.
It is not clear if our engineer was aware of the short cut joists when he ok'd using LRU hangers and we are now very concerned about using LRU hangers given the feedback from Simpson.
Please note that only a couple of joists (shown in picture) are sistered so aware that a different hanger is needed for those. Picture is meant to show gap between joist and beam.
We would greatly appreciate any feedback based on the above. Thx
(edited for clarity)
First image is view from directly below the beam and looking up. You can see the gap between bottom of double joists and beam…the gap is more like 1/2" at the top of the joist.
Best Answer
I think the joists cut short are fine because, 1) required bearing is satisfactory, 2) withdrawal out of hanger is not of concern.
1) Your 2x10’s at 16” on center spanning 12’ will support a maximum of between 100 per linear foot (plf) and 155 plf depending on the species and grade of the lumber. Therefore, the maximum load on each hanger is:
155 plf x 6’ = 930 lbs.
Lumber can withstand between 375 psi and 455 psi in compression perpendicular to grain before it starts to crush. Therefore, the MINIMUM bearing length required in each hanger is:
930 lbs. / 375 psi x 1.5” (width of joist) =
1.6” into hanger
The joists cut short at the top of the hanger is not important...there is no load on that portion of the joists, except to provide support for your subfloor.
2) Withdrawal out of the hanger is not supported by the side nails, but rather by the subfloor. That is to say, the joists cannot “move” out of the hangers because they are secured in place by the nailing of the subfloor into each joists.
Summary: If the joists extend about 1 5/8” into the hangers, they can support the maximum load that a 2x10 joist at 16” on center spanning 12’ can support.