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LVL beams and post use on block foundation


noake's Avatar
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05-15-11, 07:34 PM   #1  
LVL beams and post use on block foundation

Hello,

I built a 22'x22' workshop with 2x4 stud walls 10' tall, then a 12x12 pitch rafter roof. I set the stud walls on top of the 4"wide x 16"long X 8"high course of cinderblock set on top of the monolythic poured concrete slab.

Here is what I am wondering.....I am hoping to run some 18" tall LVLs across the 22' span of the building, then set 2x8s perpendicular on top for floor joists, plus plywood so I can basically have a 2nd story to use for storage. The 12x12 pitch roof leaves me lots of head room. I am looking to set the 22' LVLs on top of either a 4x4 post, or possibly one of this mighty-jack steel stanchons, and set it in the 2x4 wall cavity on each side of the building.

Will this load (LVL + floor joists sitting on top of post/stanchon) be OK to set on the bottom plate inside the stud wall, which is resting on the 4"x16" course of block that the walls are built upon? The bottom plates of the stud walls are anchored with the mud sill straps per and nailed per code. I kind of wish I had used the 6" wide x 16" long x 8" high course of block on the slab, but we are way past that.

Will the block support this post and beam + floor structure?

For the posts, should I go with the steel "mighty jack" floor stanchons in each wall? Or a 4x4 or 4x6 post? If I went with the 4X6 post I could even cut a beam pocket inside each 4x6 to hold the LVL beam snugly- then lag bolt through it or something like that.

Any ideas?

Thanks

 
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Bud9051's Avatar
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05-15-11, 08:04 PM   #2  
Just some questions while we wait for the pros.
How many LVLs and how far apart?
How thick is the slab, any steel?
What is under the slab, compacted gravel, soil, other?
What about using 22' I-joists all the way, 16" oc?

Bud

 
chandler's Avatar
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05-16-11, 03:58 AM   #3  
You can use the LVL (based on your answers to Bud's questions), but not on a 4x4. You will have to build a saddle at either end made up of 2 king studs and possibly 3 jacks to rest the LVL on. All will be hidden in the wall, but you need the support.
Using I-joists, you will find will be possibly cheaper than your plan, lighter in weight, easier to install, and less warpage than with dimension lumber.

 
noake's Avatar
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05-16-11, 05:15 PM   #4  
I plan on having two LVLs- spaced 8 feet apart. The LVLs are probably 2" think- 18" high and 22' long. I could go with double 16" or triple 14" LVLs but that would drive the cost way up. I was going to cantilever 3' past the LVL beam on each side (8' between beams + 3' on each side= 14' 2x8s spaced 16" O.C.)

As for the slab. The slab is 4" think on compacted sand. There is fiber mesh in the slab.

I would consider doing the I-Joists 16" OC since this would save the expense of the LVLs, and the 2x8 floor joists plus give me more headroom presumably. The only question is....what dimension I Joist would I need to run in order to span 22' without a post underneath in the middle of the room- that was the whole point of using the LVL.
Any idea on that?

Assuming I go with the LVL in the stud wall cavity- I think the width of the beam would be about 2" . Could you explain how I could build the saddle and get the two kings, and 3 jacks all under the 2" wide beam? I am not envisioning that one. I didn't think the 4x4 would suffice. How about the steel stanchon?

 
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05-16-11, 05:31 PM   #5  
If you use LVL, you would be doubling it, and that is how you would get it to fit the framing. How do you propose to cantilever off the LVL?
Use I joists in 11 1/2" and they will span 26' clear, unless I am mistaken. Rest assured someone with a TrusJoist span calculator will chime in and correct me if I am wrong. That is the beauty of the I joists. No center support is needed, and you use them just as you would your joisting, so no 2x8's would be necessary. Run the I joists every 16", or 19.2" if the specs call for it, starting at the door opening and go back to the back wall.

 
noake's Avatar
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05-18-11, 05:02 AM   #6  
Thanks for the feedback. I was planning on using a 18" high LVL- which would allow a single beam to carry the load spanning 22'. I could also use double 16" or triple 14" to carry the same load on that span. But, obviously it would be cheaper to purchase just two total 18" LVLs (one each spaced 8' apart). Then I would run the 2x8s on top and perpendicular to the LVL beams, and cantilever each 4' off the side of each beam. I will not cover the entire 2nd story with flooring- it will be more like a loft with each end open. I am not sure if that makes sense. But my question was about how to set the single (2" wide) LVL on top of either a post or a stanchon in each sides stud wall.


Each 18" x 22' long LVL will cost me approimately $190. Any idea what the I Joists that span this distance would cost? I have no problem buying them and spacing 16" OC for the ease of installation and the fact that I can attach subfloor right to the top and save the head room based on my other idea.

One question about I-Joists- I can set them on studs in each sides stud wall for most of the area I am trying to cover. But I have one area where there is a header over a double door right in the middle of the building. How would I attach to this part? Would a joist hanger be sufficient? Or must the I joist be resting on top of a post/stud. I am not sure how I could accomplish that with the door being right there.

Thanks for all of the input.

 
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05-26-11, 06:50 AM   #7  
Does anyone have any idea on this? How would I terminate one end of a I-joist if it was running into a long door header. Could I use lag bolts to secure a 2x4 or even up to a 2x12 to the existing header, then rest the end of the I-jois on the top of that? Or should I use a Simpson joist hanger like I would use to hang a joist on a deck ledger board?

 
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05-28-11, 04:11 PM   #8  
I-joists

Sorry I'm late getting into this. First, make sure the door header is of proper size to carry the weight. If it is, you can use hangers directly to the header. If not, you can probably attach something like an LVL to help carry the weight and then attach hangers to that. Also, I-joist companies make an OSB rim board that is about 1 1/8" thick and the same height as the I-joists that is used as band boards in floor packages. You could use this along the entire wall all the way around and attach hangers to that. Consult the supplier on bridging (blocking between joists) on large spans.

 
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