equivalent steel beam

[87jeepwrangler]

i'm adding a 21'x31' garage to my house, with living space above. only place i could find local that specs beams works with wood only, and they spec'd two Rosboro Big Beams along the 21' span, dividing the long length into 3 even spaces leaving the joists with 10' spans each.

the spec'd beam is 5.4375" x 16" deep, by 21' long. I have the printout the engineer gave me, but is there a way to convert that to an equivalent steel beam? hoping it saves me a few inches in ceiling height, and hoping i could perhaps throw a trolly on a steel beam for some light lifting in the garage.

 

[spy604]

If it lists the load, and the allowable defelection, then yes. Post up what you have here. Ill dig out my AISC handbook.

 

[snorky18]

I can't answer specifically without a lot of variables that you haven't have mentioned (and may not know the answer to), and some calcs, but for a 21' span to give you a rough idea you could probably get an I beam in the 6-8" tall range that would suffice for typical loading and some light lifting.

What I'm less sure of is how you would tie 2x joists into the side of a steel I-beam. There may be a way, but I'm not as familiar with residential construction.

And if you have to put the I beam UNDER the 2x joists, then it's eating your headroom, which is what you were trying to avoid in the first place.

Also keep in mind tht the heavier 8" beams could weigh 1200-1400 LBS at 21' long.

Are you having trouble finding a steel supplier for a beam, or is it just that the engineer/company you have been using only specs wood? Knowing your location could be helpful as well.

What you're looking at doing is very worthwhile (ie both increasing headroom and having a place for a trolley)-it's on my wishlist if I ever build. I would encourage you to push to find someone to spec and supply a steel beam if at all possible. They'll want to know what the heaviest load you would hang would be.

 

[spy604]

you can check this out for yourself.
http://www.toolbase.org/PDF/DesignGuides/ResidentialSteelLoad_SpanTables.pdf

Your tributary width would be 10' . Then look down the table until the span reaches 21'. That shows you need a W12x14 beam. Thats 12" nominal height X 14#/foot of length.

21*14 = 294# per beam X 2 beams = 588#
Thats $600 if you pay a buck a pound with cut charge.

 

[87jeepwrangler]

here's the printout on that beam. is that the info you would need?

to connect the joists to the beam, i would assume i'd need a drilled beam spec'd so i can attach(through bolt) a 2x to the webbing of the beam, then just use joist hangers.

the steel would only hang through the ceiling the height of the steel minus the joists.

if it was heavy enough, i'd have no problem renting a crane for a couple hours to get the beam in place. i think it's worth doing.

there are steel suppliers in my area, i'm sure i could find the beam if i knew the specs on what i needed. as for how much i plan on lifting, i may want to lift an engine on occasion, but so infrequently, that i'd probably throw a few jack studs under the beam before lifting so i didn't need to oversize the beam too much.

 

[spy604]

usually the beams are mounted with the joists on top, if you tie the joists into the side of the beam youll have trouble getting your upper floor level, and you probably wont have room for a trolley underneath.

I did this exact thing in my own garage. I laid a 2x8 on top of the beam, bolted and glued. Then i could set the joists on top of the beam and nail right to it. You do lose a bit of headroom, but you were going to have a 16" beam there anyway, so you probably come out even.

 

[snorky18]

you can check this out for yourself.
http://www.toolbase.org/PDF/DesignGuides/ResidentialSteelLoad_SpanTables.pdf

Your tributary width would be 10' . Then look down the table until the span reaches 21'. That shows you need a W12x14 beam. Thats 12" nominal height X 14#/foot of length.

21*14 = 294# per beam X 2 beams = 588#
Thats $600 if you pay a buck a pound with cut charge.

There's more than one right answer. Those tables are likely optimized for efficiency, i.e. high strength for low cost. You can go to a shorter beam with a heavier weight per foot and keep the same capacity, and get more headroom. More along the lines of say a W8x35.

It's just a question of how much $ the OP wants to pay for X" of headroom. And how much additional weight he wants to hang, which the original beam doesn't accout for, and we don't know yet.

 

[JakeKohl]

usually the beams are mounted with the joists on top, if you tie the joists into the side of the beam youll have trouble getting your upper floor level, and you probably wont have room for a trolley underneath.

I did this exact thing in my own garage. I laid a 2x8 on top of the beam, bolted and glued. Then i could set the joists on top of the beam and nail right to it. You do lose a bit of headroom, but you were going to have a 16" beam there anyway, so you probably come out even.

I've seen them through bolt with carriage bolts wood lumber to the flat webbing in the center of an Ibeam and hang joist hangers on that wood. You're still going to have to work out how to get it all level at the top but it's a start.

 

[spy604]

I've seen them through bolt with carriage bolts wood lumber to the flat webbing in the center of an Ibeam and hang joist hangers on that wood. You're still going to have to work out how to get it all level at the top but it's a start.

I have seen that too, and it works. The real problem with that for OP is that theres no room for a trolley if its done like that.

 

[spy604]

There's more than one right answer. Those tables are likely optimized for efficiency, i.e. high strength for low cost. You can go to a shorter beam with a heavier weight per foot and keep the same capacity, and get more headroom. More along the lines of say a W8x35.

It's just a question of how much $ the OP wants to pay for X" of headroom. And how much additional weight he wants to hang, which the original beam doesn't accout for, and we don't know yet.

Youre absolutly right, they are sized for economy.

A W12x14 has a moment of inertia of 88.6in^4, so we need to stay above that to maintain our deflection.
To go to a 10" beam, you would need a W10x19 - I=96.3
or a W8x28 - I = 98.0

None of this takes into account using it to lift anything. I would need a bit more info from OP as to how much he is planning to lift, and what height beam he might want.

 

[snorky18]

To attach a smaller W beam to a large W beam and keep the same top height, you can cope the top flange of the smaller beam back far enough so the web of the smaller beam can extend under the top flange of the larger beam till the web of the smaller beam touches the web of the larger beam. You can use angle as clips on both side of the connection and either bolt or weld it.

If you coped the top and bottom of the wood joist back in a similiar manner, could you use angle as clips for the wood? Maybe even make a U shape clip to support the bottom of the joist, (sort of a custom joist hanger), and make the hanger protrude enough to provide clearance for a trolley?

 

[spy604]

To attach a smaller W beam to a large W beam and keep the same top height, you can cope the top flange of the smaller beam back far enough so the web of the smaller beam can extend under the top flange of the larger beam till the web of the smaller beam touches the web of the larger beam. You can use angle as clips on both side of the connection and either bolt or weld it.

If you coped the top and bottom of the wood joist back in a similiar manner, could you use angle as clips for the wood? Maybe even make a U shape clip to support the bottom of the joist, (sort of a custom joist hanger), and make the hanger protrude enough to provide clearance for a trolley?

You lost me with the coping. If you are going to upsize the beam, you gotta do the whole beam. Well you dont have to, but thats a whole lot of work and steel is cheap. While OP hasnt responded yet, the W8x28 would be a good choice. If the joists were 2x8, we are back to the 16" tall that he had before, so no headroom loss, and without doing any calculations, is almost certainly large enough to handle an extra 1000# for lifting.

 

[87jeepwrangler]

planning on 2x8 floor joists (to match the existing house).

if i tie them into the side of the steel, then a 12" tall steel beam will only drop 4" below the ceiling joists (not enough room for a trolly).

couldn't i just get an oversized beam, and therefore more room for the trolly? a 14" beam would hang down 6" below the joists. at 16" beam would hang down 8" below.

as for how much weight i'd like to lift with the trolly, like i said above, i'd like to occassionally lift engines, but i'd be more than happy to throw a temporary jack stud under nearby for how little i would lift an engine. otherwise, it would just be lighter stuff like transmissions and transfer cases.

 

[spy604]

If you wanted a 14" beam, the lightest they make is a W14x22, which is grossly oversized. Nothing wrong with that, its just way more than you would need, safety-wise. If you thought you needed more room, there a W16x26, but now we're back at 16" and 26#, where you could save yourself some time by putting the joists on top. Your call. You only gain maybe 3" by putting them into the side, due to the need for the trolley.
Add the hassle of drilling a bunch of holes, and buying joist hangers, and messing around getting the floor flat on top, and youll see why I did it the way I did.

 

[87jeepwrangler]

i see what you're saying, spy, and it all makes sense. i guess it comes down to money vs time vs headroom.

with setting the joists on top of the steel beam, i would need to glue and screw a 2x to the top of the steel beam, correct?

so with an 8" steel beam + 1.5" 2x and an 8" joist, i'd be looking at 17.5" total height?

attaching the joists to the side of the beam, assuming a 14" beam, i'm 3.5" taller ceiling height to the bottom of the beam, correct?

also, the span table you pointed out accounts for supporting the above floor, but there are also additional walls and ceiling joists landing on those walls (not the roof though). by that span table, is it possible that the 8" beam you are referring to is actually undersized for the given load?

 

[snorky18]

You lost me with the coping. If you are going to upsize the beam, you gotta do the whole beam.

I knew I should have started with a picture....

I was thinking main steel beam, but with smaller wood joists attached in a manner similiar to this:

Though with wood I would probably want an additional angle attached to the web of the steel beam to serve as a "shelf" at the bottom of the joist to bear the weight.

 

[Fastback]

I used a "Lite Steel Beam" and was going to recommend that, but I see the page is down and the company is defunct. They do have competitors though, and a folded steel beam has huge advantages over a heavy steel beam. Deflection under its own weight at span is the thing.

 

[87jeepwrangler]

Ha. Funny. I already have a lite steel beam in my house. I put one in about three years ago when i moved a wall in my house. Super easy to work with. They are out of business tho, and i dont think a trolly would work on those.

 

[nehog]

I once spent time talking to a structural engineer who did steel. His comment stuck with me: "Despite what people think, steel is not stronger than wood, and you won't save a lot of space using a steel beam. Figure the dimensions as being the same with engineered wood and steel and you won't go wrong." (I was working on an early plan to build a garage and wanted to span so I could have no posts in the center--the resulting steel I beam was as big as a wood one would have been.)

 

[87jeepwrangler]

"Despite what people think, steel is not stronger than wood, and you won't save a lot of space using a steel beam. Figure the dimensions as being the same with engineered wood and steel and you won't go wrong."

did your guy also mention how well a trolly rolls along an LVL?

just kidding. interesting take, but the big benefit for me going to steel is the possible ability of having a built in gantry.

 

[87jeepwrangler]

I knew I should have started with a picture....

I was thinking main steel beam, but with smaller wood joists attached in a manner similiar to this:

Though with wood I would probably want an additional angle attached to the web of the steel beam to serve as a "shelf" at the bottom of the joist to bear the weight.

i've heard of steel beams with built in joist hangers, but i can't imagine that's a budget friendly option. through bolting a 2x to the webbing and then using joist hangers seems like a solid option to me.

 

[jonahbones]

Would bolting a 2x to the web of the beam on both sides add tot he stiffness of the beam ?
Would then adding noggins to the floor joists along the length of the beam also spread any point load from the trolley further into the floor structure ?

 

[Sureshot]

I think you can cap the flange with channel to increase the strength if required. My gantry crane is done that way.

To get the floor level you could rip the appropriate sized spacer to sit on the bottom flange and be screwed to the 2x on the web.

 

[nehog]

did your guy also mention how well a trolly rolls along an LVL?

just kidding. interesting take, but the big benefit for me going to steel is the possible ability of having a built in gantry.

True, true!

But you'd need to add that gantry weight (static and dynamic) to the beam's load.

 

[spy604]

i see what you're saying, spy, and it all makes sense. i guess it comes down to money vs time vs headroom.

with setting the joists on top of the steel beam, i would need to glue and screw a 2x to the top of the steel beam, correct?

so with an 8" steel beam + 1.5" 2x and an 8" joist, i'd be looking at 17.5" total height?

attaching the joists to the side of the beam, assuming a 14" beam, i'm 3.5" taller ceiling height to the bottom of the beam, correct?

also, the span table you pointed out accounts for supporting the above floor, but there are also additional walls and ceiling joists landing on those walls (not the roof though). by that span table, is it possible that the 8" beam you are referring to is actually undersized for the given load?

The table takes into account the fact that there is living space above that beam, so that includes walls, floors, people walking, etc. I did a quick calc on the additional weight for the lift, and strength wise it is completly safe, and if you were to lift 2000#, it would defect an extra .22", which is a little out of spec if the floor above was fully loaded, which i doubt it will be. They assume a 40psf live load.

Edit:
You could also notch the joists where they meet the beam, so you could gain a bit of headroom that way. Maybe notch them the depth of the 2x sitting on the beam, so 1.5".
I put about 6-8 carriage bolts to hold the beam to the board, with some constuction adhesive for good measure. Probably not needed, but oh well.

 

[87jeepwrangler]

spy, that span table says "No roof or attic loads." i'm sure it would be adequately sized to support the floor and walls, but what about the 2nd floor ceiling joists, insulation, and ceiling drywall?

also, i know you can't just drill holes in the webbing of a beam wherever you want, there are guidelines. does the same hold true for drilling in the top of a beam?

 

[spy604]

i see what you're saying, spy, and it all makes sense. i guess it comes down to money vs time vs headroom.

with setting the joists on top of the steel beam, i would need to glue and screw a 2x to the top of the steel beam, correct?

so with an 8" steel beam + 1.5" 2x and an 8" joist, i'd be looking at 17.5" total height?

attaching the joists to the side of the beam, assuming a 14" beam, i'm 3.5" taller ceiling height to the bottom of the beam, correct?

also, the span table you pointed out accounts for supporting the above floor, but there are also additional walls and ceiling joists landing on those walls (not the roof though). by that span table, is it possible that the 8" beam you are referring to is actually undersized for the given load?

spy, that span table says "No roof or attic loads." i'm sure it would be adequately sized to support the floor and walls, but what about the 2nd floor ceiling joists, insulation, and ceiling drywall?

also, i know you can't just drill holes in the webbing of a beam wherever you want, there are guidelines. does the same hold true for drilling in the top of a beam?

I wouldnt worry about a few holes in the top web for bolts, the beams are sized for deflection, not for strength, they are very low stress. Thats one of the advantages of steel. Just dont put it out on the edge and you'll be fine.

As far as the ceiling loading is concerned, you could look at the next two charts where the dead load goes to 15psf and 20 psf. If we were being very cautious, and went with the 20psf DL, that says you need at W10x19, which has an I of 96.3in4

Since you want a 8" beam, the equivilant is still a W8x28. A W8x31 would add that extra safety you might want if you were lifting 1000+ pounds.

Have you checked on the steel prices in your area? Im in ohio and bought mine last year for $54/cwt, but yours could be double that depending on location.

 

[87jeepwrangler]

haven't checked steel prices, but the first price i got on the equivalent LVL makes the steel beam cheaper even at $100/cwt.

i'm still leaning toward putting the 14" beam in there and connecting the joists to the side webbing to save on head clearance. i realize its a ton more work, time and money for only a couple inches, but its eating at me.

any idea where i can find a drilling schedule for the vertical webbing on a beam?

 

[readhead]

A dropped beam with a plate bolted to the top would be the easiest way to go in this case and would not cause any plumbing or wire issues. The other option would be a flush beam with a plate bolted to the top and using top flange joist hangers. If this is getting inspected the beam will probably be required to be covered with drywall to provide fire protection for the beam which takes the trolly out of the equation.

 

[87jeepwrangler]

regardless of what size beam i use, im gonna need to support the beam with jack studs or columns at the ends.

id prefer supporting the steel with wood if possible. what is the most appropriate/best method to sit the beam on(can it rest directly on the top plate of the wall, or does it need an additional steel plate under the beam to spread the load? and to fasten the beam to the wood? can i drill holes in the bottom of the beam and bolt it to the top plate?

 

[atfulldraw]

raise your bottom floor wall height, install your steel beam and land your joists on top of it.

it is a new build, right?

 

[87jeepwrangler]

raise your bottom floor wall height, install your steel beam and land your joists on top of it.

it is a new build, right?

the 2nd floor has to be the same height as existing 2nd floor. one of the rooms will span across both old and new 2nd floor.

i'm not afraid of the extra work to tie joists into the side of the beam.

 

[readhead]

A stack of studs under the beam is all that is required. Drill the bottom flange and put a couple of 5/8" lags down into the studs. Your building department may require a strap across the beam to pick up the framing also.
If this is being permited I would presume that the building department will require engineering on the plans for this beam and whatever other structural items like the foundation .