Best way to do a 28' clear span?

[justbarriault]

Hi all, I have many questions posted in a different thread so I think my most important question is getting overlooked or not getting the proper attention. My new garage is 28' wide with 16' ceilings and I'm putting a very short second floor in the back (28' wide by 10' long), mainly for easier access to my attic, and I'd like to do this with no vertical supports. I'm thinking either a long LVL or steel beam to span the 28' width, as I believe the LVL required would be very tall. I figure a steel beam across the front of this with a 2"x8" carriage bolted to it would allow my to nail my floor joists to that. Make sense? Does anyone have experience with this setup? I don't need to put a trolley on it, and plan to have 8' clearance below it, and around 7' above which gives me a foot to play with for beam height etc. I really don't want some monster beam that's excessive since this will have 1,000lbs or less on this small area. I'm thinking it will be used for my staircase going to the second floor and hardware storage

 

[Mike K.]

I built 28' x 60' using 14" tall I-Joists. As I remember, the spec was 14"o.c., but we used 12"o.c.. With 2x6" walls, 9'' ceiling & full second floor. The net result is a completely open floor plan.

Mike K.

 

[Cyberbear]

I did something similar back in 1986 for a two story addition next to my existing single story shop. I needed to clear span 25.5' and we used a steel I-beam that was not too large for my application. I can't remember what size the beam was but I think it was no higher than 12" perhaps more, but certainly less than a wood beam of some type.
Because of my location I needed engineered plans that specified the beam size. You can easily look on the Net and get beam sizes and load bearing charts, then simply do the math and find your proper beam size. I once studied architecture back in the mid 1960's and I used my old text book charts to determine what I needed. The engineer said I was right on but he had the rubber engineering stamp.

 

[justbarriault]

Thanks Cyberbear. I started researching that but got busy so will dig deeper. I am fortunate that I have no building codes on non-living dwellings in my town, so no stamps required. I figure about any steel beam will at least hold everything up, and then if i start to notice a sag I could always weld some additional support to it of some sort. As I'm going through different thoughts or possible issues, I'm thinking that I should leave the beam at least 1/2" to 1" short to deal with expansion/contraction of the building due to the temp changes, that way it doesn't bulge my walls. Does this seem to make sense?

 

[nadogail]

I think prefabricated light gauge steel trusses would work for you. Or a hybrid truss made of wooden chords with steel pieces as angles. Each truss would be light enough that a small crew could hoist them into place.

Steel I beams are impressive, but without a crane they can be difficult to set in place.

With time and patience, you could laminate the top and bottom chords from lumber and use EMT conduit for the angled members.

Take a look around large clear span buildings, like bus station loading areas or warehouses, take a lot of pictures. Buy the lumber, glue, bolts and screws and go to town.

Typically those trusses are set on 24 inch centers.

 

[justbarriault]

I'm not sure if you are understanding my plan completely, but I do understand what you are talking about. I'm really thinking of something very simple though. I have 16' walls up and an attic space built into my trusses, and halfway up I want a 10' long floor. I'm thinking I can get away with a beam of some sort 10' forward of the back wall to span the 28' width of my garage, and then nail 10' joists 16" OC from that to the back wall. A crane isn't an issue since I bought one to build this shop, although I do have it for sale at this point now that the garage is built. If the beam is light enough I can use my Kubota tractor with the forks on it

 

[TommyK]

For attic loading and only 280 sf you could do that with LVL's. Your lumber yard should be able to size it for you. I would think 3 16" LVL's would be overkill.

 

[nadogail]

For sure I do not understand your plan, I ***-u-me-d that your building is 28' by 60' and you wanted a clear span of 28'.

Sorry to burden you with my misunderstanding.

My mental picture was a few guys with ropes pulling 28' light weight trusses into place.

Good Luck with your project.

 

[CNGsaves]

Might consider Flitch Beam (sandwich of LVL & flat steel) instead of steel I-Beam.

 

[theoldwizard1]

I built 28' x 60' using 14" tall I-Joists. As I remember, the spec was 14"o.c., but we used 12"o.c.. With 2x6" walls, 9'' ceiling & full second floor. The net result is a completely open floor plan.

Mike K.

Either wood I-joists or parallel chord truss joists. Much lighter than a steel I-beam and likely less expensive. Steel would definitely require a crane, the others, probably not.

 

[youwish2bme]

I just finished up my 26x36 so a 25' clear span. We used 16" TJI's on 12" centers and it's like a brick **** house...

 

[bczygan]

None of these options are the correct answer until you know the load you intend to support.

Assume a live load of 50#/SF and a dead load of 10#/SF.

First, let us design the joists. Assuming no finished ceiling underneath we can use L/240. #2 and better Hem-Fir for the material. Let's try 2x6's and space them at 16"o.c.
This calculator shows a span of 9'8". Ledger and double LVL take up 5", so this is adequate.
http://www.awc.org/codes-standards/calculators-software/spancalc

The LVL has a contributing area of 5SF/LF times 60# equals 300#/LF of uniform load.
Let's use a 1.9E LVL which is readily available. From this chart we can pick a combination for L/240 which will give a deflection of 1.4".

http://parr.com/PDFs/LP%20LVL%201.9E.pdf

A beam made up of 3 of the 1 3/4x16" deep LVL's will support the load.

28' is a pretty long span with that load. I would compare steel if 16" was too deep and compare costs for the LVL plus flitch plate(s) solution, but that would need engineering. Check weights as well.

Also, the ledger needs designing that supports the other end of the joists. It also supports a 300#/LF load. It's size depends on how often it is supported and attention needs to be given to how it is fastened.

Bill

 

[csp]

The OP isn't wanting to span the 28' for the entire length of the garage.

He's wanting to install one beam ~10' from the back wall running parallel to the back wall. Then use that new beam to support joints running perpendicular to the beam with the other end of the joists supported at the back wall. He's in essence wanting to create a second floor only covering the back 10' of the garage, leaving the remaining area open to the 16' existing ceiling.

 

[jim whitney]

I did a 28'x30' garage with full upstairs with an I beam ,the I beam stands the 30' span with 2 x 10 joists it,s 6" x12" and has no problem supporting the load .i even have a trolley with 1/2 ton chain falls on it.

 

[justbarriault]

BCZYNGAN, thanks so much for such a complete answer, but CSP is correct. I'm sure a bunch of large LVL's or smaller beams running parallel with the back wall would work great, but I just don't think it needs to be that complicated for how little the weight will be up there. I think I'm going to call the steel yard and see about a 28'x2"x10"x1/4" rectangular stock piece or a small I-Beam. I know this may seem kind of odd, but I thought I came up with is putting the stairs from the main floor to this short second floor on hinges with a rope and pulley to lift it up when not in use to give me once again a fully open garage floor. When winter comes and I really like to get everything inside for a snow storm the more room I have the better. This second floor and attic space could easily go a couple months unused so why trip over the stairs. I also really need my truck/equipment bay to be available when I need it, but it will not be needed very often as I don't actually own a class 8 truck, I just deal with them and when I bring one home in the winter, I'd like it in a heated environment so that they don't freeze up on me (has happened in the past). Jim Whitney, how thick was the steel you used? 1/2"?

 

[Radix2]

BCZYNGAN, thanks so much for such a complete answer, but CSP is correct. I'm sure a bunch of large LVL's or smaller beams running parallel with the back wall would work great, but I just don't think it needs to be that complicated for how little the weight will be up there. I think I'm going to call the steel yard and see about a 28'x2"x10"x1/4" rectangular stock piece or a small I-Beam. I know this may seem kind of odd, but I thought I came up with is putting the stairs from the main floor to this short second floor on hinges with a rope and pulley to lift it up when not in use to give me once again a fully open garage floor. When winter comes and I really like to get everything inside for a snow storm the more room I have the better. This second floor and attic space could easily go a couple months unused so why trip over the stairs. I also really need my truck/equipment bay to be available when I need it, but it will not be needed very often as I don't actually own a class 8 truck, I just deal with them and when I bring one home in the winter, I'd like it in a heated environment so that they don't freeze up on me (has happened in the past). Jim Whitney, how thick was the steel you used? 1/2"?

Bczynan's answer is about exactly what CSP and you are describing - a beam across and short joists back to the wall. The three plies of LVL are what make up the beam to span that distance at the L/240 deflection.

I'm not sure you should take on this project if you cannot understand what he wrote..?

 

[justbarriault]

I re-read it and understand it better, but no, I do not understand many carpentry terms or acronyms. What did throw me off was this part here:" I would compare steel if 16" was too deep and compare costs for the LVL plus flitch plate(s) solution,". It re-directed how I was interpreting his ideas. As far as taking on the project, I'm sure I can figure out how to put up a 28' beam and a few joists. I'm not a carpenter for a living, but I managed to do a good portion of the garage build and it hasn't fallen yet and I haven't lost too many fingers. I just got a quote on 2"x8"x1/4" rectangular steel, and it's much lighter than a 10" I beam, and much cheaper of course. I'm thinking I may bump that up to a 10" to be safe, but I'm thinking it will do the job.

 

[justbarriault]

My text may have looked ornery Nado, sorry, it wasn't meant that way. Thanks for the idea and Happy Holidays to you-Justin

For sure I do not understand your plan, I ***-u-me-d that your building is 28' by 60' and you wanted a clear span of 28'.

Sorry to burden you with my misunderstanding.

My mental picture was a few guys with ropes pulling 28' light weight trusses into place.

Good Luck with your project.

 

[Radix2]

I re-read it and understand it better, but no, I do not understand many carpentry terms or acronyms. What did throw me off was this part here:" I would compare steel if 16" was too deep and compare costs for the LVL plus flitch plate(s) solution,". It re-directed how I was interpreting his ideas. As far as taking on the project, I'm sure I can figure out how to put up a 28' beam and a few joists. I'm not a carpenter for a living, but I managed to do a good portion of the garage build and it hasn't fallen yet and I haven't lost too many fingers. I just got a quote on 2"x8"x1/4" rectangular steel, and it's much lighter than a 10" I beam, and much cheaper of course. I'm thinking I may bump that up to a 10" to be safe, but I'm thinking it will do the job.

You think it will do the job? Based on what?

How much deflection do you expect in your 28' 2x8 steel rect ?

Do you know why I beams are shaped like that ? - it is because they are the LIGHEST shape with the most strength. So by simple physics, your rect stock has to weigh more to be as strong - or this light cheap stock is much much less strong.... If I get a chance I will calculate for you the deflection in a 2x8 section at 28 feet - but there is no way "it will do the job".

You need to recognize that following standard practices and having good outcomes is different from taking a wild guess on a non standard problem.

Not trying to offend you, but you really need to understand what was offered above in order to get to the place that lets you ballpark your alternatives.

 

[justbarriault]

You think it will do the job? Based on what?

How much deflection do you expect in your 28' 2x8 steel rect ?

Do you know why I beams are shaped like that ? - it is because they are the LIGHEST shape with the most strength. So by simple physics, your rect stock has to weigh more to be as strong - or this light cheap stock is much much less strong.... If I get a chance I will calculate for you the deflection in a 2x8 section at 28 feet - but there is no way "it will do the job".

You need to recognize that following standard practices and having good outcomes is different from taking a wild guess on a non standard problem.

Not trying to offend you, but you really need to understand what was offered above in order to get to the place that lets you ballpark your alternatives.

No offense taken. 16" LVL's would take up more space than I would like due to I'm bucking for 8' clearance on the first floor, and would really like at least 7' on the second floor. If you guys think a steel I-Beam is the only good way to go I'm OK with that fact. Tubular Rec steel caught my eye for the simplicity of it, and how easy it would be to carriage bolt a 2"x10" plate to it and hinge a set of stairs on somehow. Does anyone have any idea on how small of an I Beam I could get away with? I priced out a W10 x4"x3/8" earlier, but just seemed excessive. Maybe I could go down to a 1/4" thick? Radix your thoughts or alternative ideas?

 

[Radix2]

for a 1/4inx2x8x28 beam supporting a floor with 50LL/10DL you will have a 4.25" deflection and a maximum stress of 43,300psi...

 

[justbarriault]

So my dog can walk on it but I can't set a pair of vice grips on it too long. Sounds like an I beam wins!

 

[Radix2]

No offense taken. 16" LVL's would take up more space than I would like due to I'm bucking for 8' clearance on the first floor, and would really like at least 7' on the second floor. If you guys think a steel I-Beam is the only good way to go I'm OK with that fact. Tubular Rec steel caught my eye for the simplicity of it, and how easy it would be to carriage bolt a 2"x10" plate to it and hinge a set of stairs on somehow. Does anyone have any idea on how small of an I Beam I could get away with? I priced out a W10 x4"x3/8" earlier, but just seemed excessive. Maybe I could go down to a 1/4" thick? Radix your thoughts or alternative ideas?

The lightest weight W10 beam is 15lbs per foot

if we use the 60lb/sq ft loading, that beam is still going to sag 2 inches in the middle and be stressed at 25,000psi.

you will have to decide how stiff you want this designed for - LL/240 is a 1.4 inch deflection - that is the typical max for rough work like this.

A 22 lb/ft W10 beam will get you down to a 1.2 inch deflection and 15,000psi stress level - this would be a valid type of design.

See what the weight per foot of your beam is.

you might argue on a lower floor loading - how certain are you that it will stay empty forever? 40 lb live load/10 lb dead load wouldn't be too bad.

 

[justbarriault]

The lightest weight W10 beam is 15lbs per foot

if we use the 60lb/sq ft loading, that beam is still going to sag 2 inches in the middle and be stressed at 25,000psi.

you will have to decide how stiff you want this designed for - LL/240 is a 1.4 inch deflection - that is the typical max for rough work like this.

A 22 lb/ft W10 beam will get you down to a 1.2 inch deflection and 15,000psi stress level - this would be a valid type of design.

See what the weight per foot of your beam is.

you might argue on a lower floor loading - how certain are you that it will stay empty forever? 40 lb live load/10 lb dead load wouldn't be too bad.

It certainly wouldn't stay empty, but very light storage, and mainly on the rear wall. The W10 beam I looked at was 45LBs a foot. That was 3/8" thick with a 4" web. I'm assuming a 22lb beam would be around 1/4"? To make me understand a little better, LL/240, does this mean Live Load 240 lbs/SF?

 

[justbarriault]

It certainly wouldn't stay empty, but very light storage, and mainly on the rear wall. The W10 beam I looked at was 45LBs a foot. That was 3/8" thick with a 4" web. I'm assuming a 22lb beam would be around 1/4"? To make me understand a little better, LL/240, does this mean Live Load 240 lbs/SF?

And I thought my "RBM, GVW, GCVW, FMCSA, and NFPA" terms confused people haha

 

[Radix2]

It certainly wouldn't stay empty, but very light storage, and mainly on the rear wall. The W10 beam I looked at was 45LBs a foot. That was 3/8" thick with a 4" web. I'm assuming a 22lb beam would be around 1/4"? To make me understand a little better, LL/240, does this mean Live Load 240 lbs/SF?

Somewhere you should be able to find a spec that gives dimensions of the various beam weights.

L/240 is just a deflection spec - you convert to actual deflection by putting your span in as L - so in your case - 28ft/240 = .117 ft= 1.4 inches.

typical finished construction is stiffer at L/360 or L/480 to prevent bounce or cracking plaster.

 

[shortykorte]

I have box floor joist, 16" height spanning 25'. With t&g subfloor it's very solid.

Sorry for rotated picture

 

[csp]

The question isn't the joists, which will only be 10' in the OPs situation, but the beam supported at the ends which will support the joists.

Box joists mean nothing to what the OP is asking.

 

[justbarriault]

I have box floor joist, 16" height spanning 25'. With t&g subfloor it's very solid.

Sorry for rotated picture

I can't figure how to use a forum period so no worries on a twisted pic. Looks cool, thanks!

 

[justbarriault]

The question isn't the joists, which will only be 10' in the OPs situation, but the beam supported at the ends which will support the joists.

Box joists mean nothing to what the OP is asking.

Correct, thanks. Think I'm going to use a W10 I beam with a weight of around 25lbs/foot as suggested. This should still allow me to bolt on a 2x10 board and continued as planned, maximizing my headroom and not costing a million dollars. I should also be able to lift this with my tractor instead of my 40k lb crane. I will then run 2x10 joists to the end wall and use 2x8 jacks. This will also allow me to weld or bolt on a hinged set of stairs so that I'm not loosing floor space 100% of the time for stairs that I will use 1% of the time. None of this may sound traditional, but after all, there's no replacement for garage displacement!

 

[larry4406]

My former detached was 28' deep. Used attic truss with 2x10 bottom chord to clear span front to back with zero steel.

 

[justbarriault]

My former detached was 28' deep. Used attic truss with 2x10 bottom chord to clear span front to back with zero steel.

Thanks, but my trusses are already done, and are similar to what you have done. This is for a small 2nd floor in between the attic trusses and the main floor, similar to what ShortyKorte has a picture of above. I appreciate the input though

 

[bczygan]

BCZYNGAN, thanks so much for such a complete answer, but CSP is correct. I'm sure a bunch of large LVL's or smaller beams running parallel with the back wall would work great, but I just don't think it needs to be that complicated for how little the weight will be up there. I think I'm going to call the steel yard and see about a 28'x2"x10"x1/4" rectangular stock piece or a small I-Beam. I know this may seem kind of odd, but I thought I came up with is putting the stairs from the main floor to this short second floor on hinges with a rope and pulley to lift it up when not in use to give me once again a fully open garage floor. When winter comes and I really like to get everything inside for a snow storm the more room I have the better. This second floor and attic space could easily go a couple months unused so why trip over the stairs. I also really need my truck/equipment bay to be available when I need it, but it will not be needed very often as I don't actually own a class 8 truck, I just deal with them and when I bring one home in the winter, I'd like it in a heated environment so that they don't freeze up on me (has happened in the past). Jim Whitney, how thick was the steel you used? 1/2"?

The design I did above is one single beam from sidewall to sidewall. Then wood joists running from that beam to the rear wall and a ledger running across that wall. This is the same layout as you described. The wood joists would be hung from joist hangers. If you do a steel beam, you will need to have a 2x bolted to the web so you have something to fasten the joist hangers to.

Also note that the ledger can be kept to a smaller size if it is supported more often, as it can be, since it is on a wall. And I prefer supporting it with wood columns and lag bolts as mentioned by someone above.

Understand?

Bill

 

[justbarriault]

The design I did above is one single beam from sidewall to sidewall. Then wood joists running from that beam to the rear wall and a ledger running across that wall. This is the same layout as you described. The wood joists would be hung from joist hangers. If you do a steel beam, you will need to have a 2x bolted to the web so you have something to fasten the joist hangers to.

Also note that the ledger can be kept to a smaller size if it is supported more often, as it can be, since it is on a wall. And I prefer supporting it with wood columns and lag bolts as mentioned by someone above.

Understand?

Bill

10-4 I get you now. Do you think a steel beam is easier and strong enough?

 

[theoldwizard1]

I have box floor joist, 16" height spanning 25'. With t&g subfloor it's very solid.

That is also called a parallel chord truss. Can be made out of steel.

 

[bczygan]

10-4 I get you now. Do you think a steel beam is easier and strong enough?

A steel beam isn't easier since you need to attach a nailer for the wood joists. And I would use steel columns for the steel beam. What it gets you is less depth.

Is it strong enough? Strong enough for what? The loads we are talking about and the spans involved can be supported with wood or steel or a combination.

Strong enough? Not unless it's engineered and sized to be strong enough. Same is true for wood.

The decision on which to use depend on the depth you need and the money you are willing to spend.

The steel beam needs engineering as was done for the wood one.

And as someone mentioned above, you can always change the loads you intend to support. It could be 40#LL and 10#DL.

Bill

 

[bczygan]

Another solution in wood would be a truss designed as a wall, with an opening sized as a door.

Bill

 

[MagKarl]

It really comes down to two choices, a beam that's taller than you want, or warm up to the idea of a post so your spans are cut in half.

 

[myredracer]

And if a clear span beam, depending on soil conditions, may need to pour a pad footing (integral with footing) where the posts for the beams are.

Curious - is this a permitted job and if so, wouldn't you need the beam to be engineered and signed off?

 

[csp]

I think this is the first thread I've seen on this site related to sizing load bearing structure where the OP wasn't immediately directed to an engineer to design it properly.