Connect Steel Plate to Existing Wood for Removing Load Bearing Wall

[AKSherpa]

I have a friend that would like to remove the wall in the attached picture and provide a 12 ft wide opening. The wall is supporting approximately 92 sq. ft. of sloped roof covered with clay tile and 60 sq. ft. of flat roof with membrane. For the factored vertical loading I have calculated the maximum shear at the left side to be 5,800 lb's and the maximum moment at roughly 58" from the left side to be 22.5 kip-ft. I am looking at either a 3/8" x 12" steel plate or a MC 12 x 10.6 steel channel, both A36.

I am interested in thoughts concerning screwing the steel plate or channel to the wood to support the load currently carried by the wall. I am particularly interested in information concerning "modern" lag screws such as those manufactured by "Screw Products, Inc..

Note, the 2 x 10 at the top of the wall is a single 2 x 10 rim board for the flat roof.

Thanks

 

[jayrod12]

12 ft isn't incredibly far, why not do it out of engineered lumber. Deflection aside, a 2 ply 11 7/8" deep lvl would do the strength requirements.

 

[AKSherpa]

Good point jayrod12. I recommended moving the ductwork, propping up the wall and installing a 4 x 12 wood header or something similar. They are set on not moving the ductwork and are determined to bolt a steel plate to the living room side of the wall.

I am interested in thoughts concerning lag screwing the steel to the wood. In particular bolt size, pattern, # of bolts and spacing at ends for shear transfer, the bolting options of either the 2 x 4 wall top and bottom plates or the 2 x 10 rim board. Also any experiences or information concerning the use of "modern" style lag screws, such as those manufactured by "Screw Products, Inc." with attached washer, for attaching steel plates to wood.

Thanks

 

[bhiggins]

You have that stud pack taking the point load from the ceiling beam above, how do you plan on transferring the roof load from the stud-pack to the side of your new steel beam? Seems like it wouldn't work. Plus splicing those existing beams with steel seems wonky in general.

I'm not aware of any lag screws that can penetrate 3/8" thick material. This is traditionally done with (2) rows of 5/8" through-bolts @ 12" to 16" O.C. and extra bolts at the supports.

 

[AKSherpa]

Thanks bhiggins. I am with ya on the wonky and appreciate your opinion and info.

In my mind the only use for the existing 2 x 10's in design calc's is to provide lateral restraint to prevent steel plate from buckling. As far as lag screwing thru the steel plate I envision drilling the holes thru the steel. Also, very good point as to carrying the point load to the beam. In my calc's I am using a 6.3 kip point load at 54" from left end of proposed steel beam. That gets back to my original question.

I am interested in information concerning carrying the calculated loads to the existing wood. Is it possible to carry the loads to the existing single 2 x 10's and 2 x 4 plates? As far as the "modern" lag screws I ma referring to common screws sold at lumberyards that are "fairly new" on the market advertising themselves as alternatives to traditional lag screws. The new style claims much higher shear and pullout strengths than traditional lag screws of similar diameter. I am interested in hearing from anyone with experience or advice for fastening a steel plate to wood with either traditional lag screws or the newer style screws. Specifically, what kind of shear and pullout strengths could be achieved connecting to the single 2 x 10's and 2 x 4's?

Thanks

 

[bhiggins]

Seems like the contractor just wants a "screw it on" solution that doesn't exist. The easiest and cleanest solution I believe is to do a 2-ply 11-7/8 LVL connected to the 2x10's with screws such as Simpson SDS screws, construct a new stud pack from the LVL to beam above to take the roof load, then finish with new framing above the beam flush to have a clean appearance- kind of like a furr-out.

 

[AKSherpa]

Thanks bhiggins.

Are you suggesting supporting the LVL with jacks studs under the ends or just screwing it to the existing framing?

Also, I am looking at a table that indicates the 2 ply 11-7/8" LVL has a moment carrying capacity of 18 kip-ft. I have calculated a maximum moment of 22.4 kip-ft.

 

[bhiggins]

Forte by Weyerhaeuser is an excellent, easy, and free program for designing wood members. You should get more capacity if you consider the fasteners as bracing your beam. Or you can go as deep as you want if the end product will be concealed. I would use jack studs on the new beam, who knows what will be remaining when the contractor removes the existing wall.

 

[AKSherpa]

Thanks for the info bhiggins, much appreciated.