I have one section of the first floor with I beam engineered lumber 11-7/8" joists to span 20 foot area of a 20x20 room, so we have some open space in the basement. The other part of the house has 2x10 floor joists, so this is making the floor height different and it needs to be the same height on the first floor so the hardwood flooring can be installed. Can I use joist hangers nailed to sill plates for the I beams and drop the joists down inside the foundation wall to give them the same height as the 2x10s?

The framer is supposed to start on Friday, by the way.

  • 6
    Your whole plan should have been engineered such that this floor height thing would be no question - just look at the plans (blue prints). – Michael Karas Nov 16 '16 at 5:28
  • @MichaelKaras Sadly some designers make decisions in a vacuum giving no thought to method of construction, complexity, cost, etc. The difference in floor height may not have been reconciled in the construction documents and/or the owner/framer/GC may prefer another solution than the one currently drawn up. – Damon Nov 21 '16 at 9:11
  • 1
    Michael Karas is right--this is one of the fundamental functions of a designer. Their product is worthless otherwise, and I'd put it in their lap to resolve. So, this becomes a question for your local building inspector. The question is too broad and complex for some yahoos on the internet to answer for you. – isherwood Nov 21 '16 at 15:22

The answer to your question is yes, you can drop the joist lower into the basement via different means depending on construction method.

Although typically in most basements the joist do not hang inside the foundation wall; they either sit on top of framed basement walls which can be easily lowered in height given basement walls typically have every stud cut to reconcile an uneven floor; or they sit on top of the foundation wall and the foundation wall would need dropped in the area of the deeper joist.

As a general rule, we avoid supporting things by ledgers if we have the option of sitting on top of something.

Another option that may not be of much expense is to raise the depth of the other joist to 11-7/8"; a plus is using a minimum strength 11-7/8" I-joist would give you a very stiff floor compared to the 2x10's. It would also simplify the framing a bit to have a cohesive floor depth throughout the main level.

| improve this answer | |

Not the answer you're looking for? Browse other questions tagged or ask your own question.