Can you put floor joists on a steel I-beam or do you need a plate on top of the beam 1st?

Question

Hello,

I am building a house that is 26' x 40' I would like to have a steel beam spanning the 40' length at the center of the 26' wall over the basement. Right now I have a choice if I want the beam flush with the perimeter sill plate, or lowered 1-1/2" and have a sill plate on top of the beam. There will be a support column at 15'-10" supporting the beam. The ends of the beam will be in pockets in a poured concrete wall.

The house will be a stick framed with no load bearing interior walls. The basement will be finished with drywall on the ceilings and the above floor will be 3/4" hardwood. The joists will be blocked and toe-nailed to the foundation wall sill plate.

I was wondering if you can tell me:

- What are the advantages and disadvantages resting the joists directly on the steel beam?
- If I do need a 2-by plate between the joists and the beam must it be pressure treated?
- What size beam and column I will need and how much should I expect to pay?

Thanks for your help!

How do you "nail" into solid steel?

Answer 1

The most secure way to attach the sill to the beam is to drill through the plate and the beam. Run lag bolts through them and wrench it tight. Will hold better than any powder actuated gun.

Answer 2

Typically, the beam is flush with top of the foundation wall (whether block or concrete) and then a sill bolted down to the foundation. Anchor bolts in the masonry wall, bolts in the steel.
Advantages
When you specify the steel for the foundation, it is a bit easier to make the steel flush with the top of the wall.
Also there is an easy nailing surface with a plate on the steel.
Yet another reason is wood will slowly compress over the years. The sill will distribute it out.

And don't make it pressure treated. Answer above me is right.

As far as sizing the steel, call an engineer. But the contractor that sets the steel may be able size it, too.

Answer 3

Steel Floor Joists

Answer 4

It can be done either way, but codes here require the joists to be tied down against uplift. useing a sill board makes this easier. Sills on steel don't need to be pressure treated. Size of beam must be calculated by an engineer for the company selling you the beam. It is possible to have a steel beam rated for no support columns.

Answer 5

The way I have always done it is with a sil plate nailed to the steel beam. Then you can easily nail and hurricane clip the floor joist to the sil plate. In fact, that's a requirement per code in FL where I build to prevent uplift from hurricane type winds. Of course you attach the plate with a .25 caliber powder actuated nail gun like a Hilti. Don't forget to yell, "Fire in the hole!" lol
I would advise against using pressure treated against the steal beam because the new chemicals used in treated lumber is highly corrosive. Maybe OK if you put a layer of felt paper (tar paper) down first. Actually I still wouldn't use treated, because all the fastners you use in it will be totally corroded to nothing within 5 years. There are alot of studies going on right now about this. You may want to research this. Right now in most states treated lumber is not required to be used until it's approved under the new building codes.

Answer 6

I agree with papercut's answer,,,,but instead of using Pressure Treated lumber (ACQ is what the chemical is) and the tar paper (felt) I would strongly recommend using a Borate treated board as you plate. Borates will not have the adverse affects that the ACQ or the new MCQ treated lumber will have on the beam.

Answer 7

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Truth is, I've been a carpenter for almost 36 years, and I haven't found anything like this for less than 10's of thousands of dollars.

Answer 8

if i used a sill plate i would have some threaded studs welded to the top of the beam before it was set...saving a lot of hassel attaching the sill plate later...

Answer 9

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Answer 10

james m. I think you mean carriage bolts, not lag bolts. Lag bolts do not have nut threads, they have screw threads.