Building second floor in a shop

[69Cat]

I'm going to put this out here and see if there are some other solutions to consider.

I need to span a 26' wide space (50' long) above my main shop to put in a 2nd floor for storage of the usual junk that collects through the years. Would estimate a 40 lb/sq ft loading at the maximum, keep in mind the heavy stuff would be around the edges and certainly not in the middle of the 26' span.

Due to screw up in the building I got a 12:1 roof pitch instead of 12:2 pitch so I am left with a little less headroom than planned and so I want to have a floor with a depth of 10 inches or so. Engineered wood trusses are 18" or 24" high for what I need and I have to run 8" joists on top of that too so I run out of room fast.

Thinking of using W8x28 Ibeams to span the 26' spaced every 12' and then put 2x8s into the webbing to bridge the 12' between I-beams.

Does anyone know how to calculate the deflection on an I-beam with a given span?

For securing the joists to the I-beam I can think of two options:
1. Angle brackets welded into the I-beam web and bolting or nailing the joists to the bracket (as per attached sketch)
2. Make a wooden header to fit inside the I-beam web and bolt it to the I-beam so that I can nail traditional joist hangers to wooden header.

Anyone try and do anything like this or have other ideas to provide a 26' clear span and minimum depth of floor?

Ken

 

[A_Pmech]

Ken,

You should have a look at two books:

"Wood Engineering and Construction Handbook"
By: Keith F. Faherty and Thomas G. Williamson

"Manual of Steel Construction"
By: The American Institute of Steel Construction

While I'm not aware that the Wood Engineering and Construction Handbook contains an example of exactly what you're planning to do, it will give you a few ideas.

Have a look at the Manual of Steel Construction for acceptable beam loading and spans, as well as attachment details for eccentric loads, such as your joists.

 

[GeorgiaHybrid]

Ken

I can get you the deflection table on a W8x28 in the morning. I don't think a beam that small will work for a floor load though. I would think something in the range of a W12x26 or W14x22 would be required. You might also think about using just the nailer on the bottom flange and skip the connection to the web. Add blocking between the joists to limit rotation and you should be OK.

Also just noticed that you are north of the border and the governing codes there use LRFD design and the CISC manual. As always, have a local engineer take a look at the design when you are done. You do NOT want to be under a load of steel that has a "boo boo" in the design and falls. There are times that engineers are worth their money. This is one of them.

 

[twostory]

My garage has a second story. I used 16 inch high wood Ibeam, 16 inch OC. The span is 26 ft. Your set up is very similar to mine. The second story is a little bouncy, but it can take the 40 #/sq ft load easily.

 

[kbs2244]

Check into the "Z-web" type roof joists.
They are lighter and cheaper then "I" beams.

 

[GeorgiaHybrid]

69Cat,

The maximum span of a W8x28 listed in the manual is 20-0 with a maximum total uniform load (in kips) of 27.1 (ASD) and 40.8 (LRFD) The deflection at that loading would be 1.7 inches or so. You need to get an engineer involved with this one and make sure to let him know what you are planning to place on the floor. Std loading would not include things a lot of us put in the attic (car parts, lawn mowers, etc.).

 

[KMR Construction]

once the beam is sized your local steel supplier can fabricate one with holes predrilled. bolt some 2x's in there and hang your joist off that.

 

[billfish111]

Hi Ken, steel is getting cheaper and if you went a little larger on the I beam you could engineer it for a hoist with trolly wheels that run on the bottom of the I beam. Simpson makes hanger that are designed to fit the top of an I beam for your floor joists. Good luck. Bill.

 

[69Cat]

Good info so far guys, thanks for the input - if you have anything else then please mention it.

GeorgiaH, I think I will call an engineer and see if I can get a quick calculation done. I found some data on the internet for I-beam ratings but I don't understand the terminology like you used in your post so I am at a loss to understand the data. A 12W would fit my height restriction but wouldn't want to go any taller if I could avoid it. The idea of just blocking on the bottom of the web is practical solution with blocking between joists. One inch of deflection would be fine since I would use plywood for the flooring and for the roof of the main level so wouldn't have to worry about drywall cracking and such.

I'll look into a hanger for I-beams - never thought that such a thing would already exist but now I can imagine it is not an uncommon application.

Attached is a sketch using a header bolted into the webbing and thus allowing basic joist hangars to be used. The additional 2x's bolted to the webbing should strengthen the I-beam and thus may help, but would need some engineering done to confirm that. This option adds a little more cost and time for me vs the first option (or what GeorgiaH suggested).

 

[GeorgiaHybrid]

You should be able to use a 12" beam for what you are wanting to do. Depending on the bldg code that you have, a W12x22, W12x26 or W12x30 should work. You could also add a wood nailer to the top flange to give you something to nail the flooring to. If you go that route, it might be easier to use a simpson hanger like billfish mentioned as you will have roughly 13" from the top of the bottom flange to the top of the nailer. That would be a LOT of blocking to bolt onto the flange (7 1/2" joist + 5 1/2" of blocking) or you could go to a 2x12 floor joist (11 1/2 + 1 1/2 blocking) and possibly space the beams further apart.

Food for thought when you talk to an engineer.