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I'm preparing to remodel my basement. A steel I-beam runs the length the of the basement with vertical steel columns spaced periodically across the span. The beam is 5" wide and 8" tall. I'm considering constructing a 2x4, non-load bearing wall directly under the beam but I'm not sure how to attach the 2x4 framing to the underside of the beam.

Here's a picture of the beam: steel i-beam

How can I attach a 2x4 wall frame to the underside of a steel I-beam.

  • what diameter are the columns that are holding this I-beam up? – ThreePhaseEel Mar 24 '15 at 1:02
  • The columns are 3" diameter. Will that impact how to attach the framing? – Spig Mar 25 '15 at 10:57
  • You'll have to adjust the studs to make sure you don't have a stud trying to go where a column already is :) – ThreePhaseEel Mar 25 '15 at 22:14
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You have a few options.

Frame around the beam.

This is probably the easiest method, though it changes the dimensions of the room slightly. Simply build your wall either in front of, or behind the beam. Attach the top plate to the joists.

Weld studs to the beam

You could weld threaded, or non-threaded rods (studs) to the bottom of the beam. Then drill holes in the top plate to align with the rods (studs). If you used threaded rods, use a washer and nut to attach the top plate.

Nuts and Bolts

Drill holes through the top plate and the beam flange, then use nuts and bolts to attach the top plate.

Powder actuated fasteners

You could use powder-actuated fasteners to attach the top plate to the beam.


WARNING: For any method that alters the beam in any way, consult an engineer for fastener schedule, size, and placement.

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    That warning is critical. Anything that alters that beam in any way effects its load bearing capacity and could bring the whole house down. The engineer will not only tell you what kind/size fasteners to use, but also where in the flange you can put them. – FreeMan Mar 24 '15 at 1:33
  • Powder actuated fasteners is the way I have always seen it done. A 2X6 wall is a nice touch, hides the beam and post too. – Jack Mar 24 '15 at 4:13
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    Offsetting the wall in front and enclosing the beam and the neighboring HVAC supply (barely visible in the picture) in a soffit in the adjacent room seems more appealing than involving a structural engineer and altering the beam. I've also considered using the lower ceiling space for closets for the two rooms. – Spig Mar 25 '15 at 11:12
  • I’d advise against 1) modifying the steel beam in anyway, including drilling holes in it, welding anything to it, etc. because you can change the dynamics of the composition of the beam, and 2) installing anything (studs) under the steel beam which will transfer a load to the floor when the steel beam deflects. You’d better be sure you understand the amount of load and the resistance the beam will withstand or provide an adequate slip joint for the studs. – Lee Sam Nov 26 '18 at 5:11
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Notice that sill plate sitting on top of the beam? Held on with some nails hammered part of the way in, then bent over the flange? Do the same with your top plate. The sill plate has the advantage of gravity holding it in place, so you'll probably want to put more bent nails in, especially if you'll have kids down there playing who may be running into it.

Since the wall's not load bearing, it just has to stay vertical, and that should do it.

To address Tester101's valid concerns:

You will need to use a 2x6 to match up with the width of the beam. You can build the 2 x 4 wall to one side of the 2x6 and have all the 'ledge' on the other side (suitable for the utility room side, if there is one), or you could center it and have a small bump on either side.

If you go for the uneven build, you'll get an offset of (5 1/4" - 3 1/4") 2" on one side. If you drywall that, the sheetrock will take 1/2 - 3/4" of an inch.

If you center the support wall, you'd have 1" on each side leaving 1/4 - 1/2" after dry walling (depending on thickness).

You could, of course, build the whole wall out of 2x6, and that resolves all the above issues.

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    If the beam flange is 5" wide, and a 2x4 is 3.5" wide. How would you get the bent over nails to grab both sides of the beam? And if you only use bent over nails on one side of the wall, how do you prevent the wall from moving the other way? – Tester101 Mar 24 '15 at 0:50
  • This wall will have to be built in sections anyway -- note the detailing at the top of the structural column holding the I-beam up! – ThreePhaseEel Mar 24 '15 at 1:02
  • The bent over nails will also be in the way when you put up drywall. – Tester101 Mar 24 '15 at 3:46
  • I like the idea of a 2x6 wall. I'd noticed the nails on the sill plate and thought wondered if the same would work for the top plate of my framed wall. Speaking of drywall, would I need to add some structure in the hollow of the I-beam to provide backing to the drywall enclosing the beam? – Spig Mar 25 '15 at 11:15
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build your wall on one side or other securing top and bottom plate so beam and wall don't move. on the other side use I joist to box in or wood frame it in or use of steel channels to enclose it.

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