20 ft clearspan

[benchracer1]

I am building a mezzanine that will be 20 long and 10 ft deep. Obviously the joists will be about 10 ft long . I need to go with 20 ft. Clearspan. I'm going to use an engineered beam. I've looked at the tables and they are all quite confused. Can anybody tell the proper beam size for this application?

 

[GMCGarage]

I am building a mezzanine that will be 20 long and 10 ft deep. Obviously the joists will be about 10 ft long . I need to go with 20 ft. Clearspan. I'm going to use an engineered beam. I've looked at the tables and they are all quite confused. Can anybody tell the proper beam size for this application?

Looks like a PSL 1.8E 1.75"x24" is in the ballpark. Make sure you design your bearings correctly, thats alot of load coming down.

 

[jbwilkins]

Looks like a PSL 1.8E 1.75"x24" is in the ballpark. Make sure you design your bearings correctly, thats alot of load coming down.

Look at laminating multiple beams together before going with something like a 24" beam, 2-3 (maybe more) shorter beams can probably be designed to work, and be easier to source ....You're also losing a lot o headroom with a 24" deep LVL......

I'm no engineer so I'm not going to suggest anything, but I'm looking at this from a purchasing standpoint (what I do for a living)....

 

[Samh]

I am building a mezzanine that will be 20 long and 10 ft deep. Obviously the joists will be about 10 ft long . I need to go with 20 ft. Clearspan. I'm going to use an engineered beam. I've looked at the tables and they are all quite confused. Can anybody tell the proper beam size for this application?

Those charts are hard to read. The one I used gave a value on load per linear foot. So a 50lbs/sqft on a 16 tributary value(which is half the distance of joist on either side of the beam) was 800lbs/linear foot. Which meant 2 1-3/4"x16" LVLs sistered together. To elaborate further, a 10ft floor joist would have a tributary value of 5 ft, as only half would be carried by the beam. Using 50lbs/sq ft would give you 50x5=250lbs/linear foot.

If unsure, your local lumberyard can take your specs and run it through their software to size appropriately.

 

[strutaeng]

Somewhere in the neighborhood of 16" deep minimum, either the sistered (2) 1 3/4 LVLs or 3 1/2 PSLs for your typical "light-wood" construction and loading.

LVLs vs PSL vs. etc. will depend on availability. As mentioned already, make sure you have supports that can carry the load, all the way to the foundation.

I would do a spread footing for this type of load at each support...5,000lb at each end +/-

Good luck.

 

[brewchief]

I would also consider using I joists and running them the long way, they might end up cheaper then a beam and regular joists.

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[theoldwizard1]

I don't find them hard to understand (but maybe I am missing something).

You need to know your load, your span and you joist spacing (typically 16" O.C or 24" O.C.). The way I read it, for a 20' span, 24" O.C. and a 40 lb per sq ft live load you will probably need a 12" TJI 230 wooden I-joist. You would need 6 of them, and they would have to be attached to something much stronger than an existing wall (ledger supported by 4x4s under each I-joist).

If you are planning on running the joists the short way, you are looking at a steel beam. Also, proper support columns (not attached to the walls).


Do it right, or don't bother !

 

[Diesel Dan]

Second floor of my living quarters have 24' clear span engineered floor joists, 16 o/c.

 

[Stuart in MN]

Without saying what's going on the mezzanine, it's pretty difficult to guess what size beam you need. Will you be storing boxes of Christmas ornaments, or your collection of anvils?

 

[benchracer1]

It's just for my vintage dirt bikes. Probably 6 of them side by side

 

[mike93lx]

Look at laminating multiple beams together before going with something like a 24" beam, 2-3 (maybe more) shorter beams can probably be designed to work, and be easier to source ....You're also losing a lot o headroom with a 24" deep LVL......

I'm no engineer so I'm not going to suggest anything, but I'm looking at this from a purchasing standpoint (what I do for a living)....

No need to lose headroom. The top of the beam doesn't have to be in the same plane as the joists. Hang them flush with the bottom.

 

[GMCGarage]

Look at laminating multiple beams together before going with something like a 24" beam, 2-3 (maybe more) shorter beams can probably be designed to work, and be easier to source ....You're also losing a lot o headroom with a 24" deep LVL......

I'm no engineer so I'm not going to suggest anything, but I'm looking at this from a purchasing standpoint (what I do for a living)....

He didnt state he had a headroom problem, and with his lack of knowledge I didnt want to suggest a 2 or 3 ply beam that would need proper connection design between the plys. I went with the most economical also in mean of amount of material.

 

[GMCGarage]

Second floor of my living quarters have 24' clear span engineered floor joists, 16 o/c.

Hes looking for a beam design, I think he has his joists already.

 

[Diesel Dan]

I am building a mezzanine that will be 20 long and 10 ft deep. [Obviously the joists will be about 10 ft long [. I need to go with 20 ft. Clearspan. I'm going to use an engineered beam.

Hes looking for a beam design, I think he has his joists already.

Was just pointing out engineered floor trusses will clear span 20'+
Doesn't say if he has joists yet.
Without knowing more design details I'd consider running the joists longs ways.

 

[benchracer1]

Actual don't have the joists yet. Kinda just in the design phase. I will however be using either 9 7/8 or 11 7/8 tji joists. I was hoping to use an 11 7/8 lvl or glulam beam beam possibly 3 ply. That would keep it consistent with other elements in the shop. Using the joists long ways might be an option. As a last resort I could add a support post but prefer not to....steve

 

[mike93lx]

If you want to do this right, get an engineer to look at it. You are talking about a very significant mezzanine.

If it was me, I would use the information here to inform my discussion with an engineer who would be able to look at the building and consider your needs in person

 

[larry_g]

Just spit balling out another idea here. You don't want a center support post in the beam, OK. Can you have a support post 18"-24" in from each end? This cuts your beam length ~20% reducing the cross section of the beam a lot. Use the area between the support posts and the outside wall as storage cabinets, peg board wall, or whatever you can imagine. If you have work benches on the side walls then the support posts can be the end support of the bench.

lg
no neat sig line

 

[GMCGarage]

Actual don't have the joists yet. Kinda just in the design phase. I will however be using either 9 7/8 or 11 7/8 tji joists. I was hoping to use an 11 7/8 lvl or glulam beam beam possibly 3 ply. That would keep it consistent with other elements in the shop. Using the joists long ways might be an option. As a last resort I could add a support post but prefer not to....steve

Based on what you are going to be storing up there, then the LL could be reduced down to 50 psf. With that, a 3 ply 11-7/8" beam would work, the deflection is a bit more than I would like, but i doubt you are going to get the full 50 psf everywhere. Its going to be a heavy beam to place, have some help!

Why a TJI? Just to match other items? a 2x12 should be sufficient.

 

[mcbane]

I suggest you cost out both options. Dealing with the point loads under a 20 ft beam can be costly if you have a lightweight slab. Even more costly if there are hydronic tubes in that slab. If those costs are steep, the use of 20 ft engineered joists might be cheaper since that does a better job of distributing loads.


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[rburke65]

Consult an engineer.

 

[matt_i]

Here is one way to proceed.

Download this manual
https://www.bc.com/versa-lam-lvl-span-size-chart/

I chose eastern US but the other one will work too.

On page 28 of the .pdf file there's a distributed load chart for L/360 deflection for "VersaLam 2.0 3100 series beams".

Spans go down the left column, lets choose 20 because of the 20 foot span..

So how to come up with the live load. You have 200 sqft, lets throw in 50 lb/sqft for live loading. 10,000 lbs total. Because its max it can be divided between the two long ends, so 5000 lbs per long end. Check 5000 lbs / 20ft span = 250 lbs/ft.

So we look along the middle row of the 20' span row until you find a value > 250 which there is in the "double ply 14 inch LVL" column with a value of 296.

You build your deck with double 14" LVLs across each 20' span per the table.

There's a lot more to it than that of course. The .pdf just addresses the downward vertical load on the beam. The main concern I personally would have is for sway (side loading) and how to brace the legs. That connection at the upper corner of the under-deck bearing the moment load is the most significant and critical, and that is where I would recommend spending a lot more time on the design.

Make sure you check this with the product you are actually using. This isn't a design guideline, just a theoretical example.

 

[benchracer1]

Thanx guys. I'm a bit out from starting this. I have a 5 inch slab and it will be free standing. . I m also going to price a steel beam....steve

 

[mike93lx]

Having a 5" slab is different from a wood floor. Just added 63 psf dead load instead of maybe 10. 3 ply 11.875" is out the door.

3 ply 1.75x14 microlam LVL 2.0 E should be in the ball park.

If free standing you now have stability issues to deal with.

I would spend the 500-1000$ and get it engineered. Your in a seismic area, and having 15,000lbs of concrete up in the air you need to make sure its secure.

Concrete in the air? Huh?

The floor slab is concrete

 

[theoldwizard1]

We are fighting some "terminology" issues ! I believe what the OP wants is a beam that spans 20' (without intermediate supports) and that he can then run joists from a ledger on the back wall to the beam.

The way I read page 5 of Eastern BCI and Vers-Lam Builder Guide that beam would have to be at least a 6x16 LVL ! A steel beam might be cheaper and actually lighter ! Lally columns would be required at each end. Also these columns need to rest on a "full depth" concrete footing, not just the floor.

Joists should rest on top of the beam or be attached with proper brackets (NOT simply toe nailed). A ledger along the back wall for the joits to rest on is questionable. If that wall is just a 2x4 stud wall, the ledger should be supported down to the floor with edge-wise 2x6s, 24" O.C.

 

[outdoorspace]

Just use floor trusses on the whole thing with no joists. My 24x13 clearspan loft was $1200 for the trusses and supports 75 lbs/sqft.

 

[GMCGarage]

Concrete in the air? Huh?

The floor slab is concrete

Dude! I read that as his slab on the mezzanine was concrete!

Is a wonder anything ever designed on here stands up!

 

[Diesel Dan]

This thread has perfect timing.
Stopped at a co-workers place and he was asking me about a mezzanine for storing "junk". He was looking at about a 22x10 with a 22' beam and 10' joists. He was planning a support post but didn't like it. Pretty sure he is going to go with 22' floor trusses now. If he does the truss build one end will be sitting on a wall and the other will just need a header along the barn wall.

Floor trusses

Man I miss having a Menards local.

 

[matt_i]

Imo steel is a choice that needs some second guessing.

- any connection to wood has to be analyzed, fabricated, usually involves stick welding and/or drilling large (> 1/2" dia) holes for structural bolts.
- someone has to cut the beam to +/- 1/16" of planned dimension. Not a thing that can be done with a circular saw.

All of that takes more time and capability than working with LVLs which can use adhesives, structural screws, nails, and cuts with a circular saw....just like regular wood framing.

 

[mike93lx]

This thread has perfect timing.
Stopped at a co-workers place and he was asking me about a mezzanine for storing "junk". He was looking at about a 22x10 with a 22' beam and 10' joists. He was planning a support post but didn't like it. Pretty sure he is going to go with 22' floor trusses now. If he does the truss build one end will be sitting on a wall and the other will just need a header along the barn wall.

Floor trusses

Man I miss having a Menards local.

A "header" may be inadequate (do you mean ledger? If really a header, make sure it is big enough). I would build a wall to support the other end properly. That is a lot of weight to have bearing on only nails

 

[GTO]

Looks like a PSL 1.8E 1.75"x24" is in the ballpark. Make sure you design your bearings correctly, thats alot of load coming down.

This is false information,please consult an engineer or architect....
fyi:A PSL starts @ 3-1/2"....you are speaking about a LVL they are 1-3/4".

Do not expect anyone here to spec a beam for you on here.

 

[spudley]

A "header" may be inadequate (do you mean ledger? If really a header, make sure it is big enough). I would build a wall to support the other end properly. That is a lot of weight to have bearing on only nails

The manufacturers calls for 3.5" bearing plates on walls for floor trusses. That said I'm not sure why the OP doesn't just go the long way and skip the beam as floor trusses are more than adequate to support his loads. Glue and screw some 3/4" sturd-i-floor on top and he's set.
BTW, anyone know how he's getting these dirt bikes up there?

 

[Diesel Dan]

A "header" may be inadequate (do you mean ledger? If really a header, make sure it is big enough). I would build a wall to support the other end properly. That is a lot of weight to have bearing on only nails

Header/ledger could go either way? You have truss headers that span 8-12 feet and support the roof load. Ledgers not so much? Definitely no on the nails. I wouldn't use nails on the truss header either even though many builders do. Where it attaches to the post he could run vertical supports down to the floor as wheel.

The manufacturers calls for 3.5" bearing plates on walls for floor trusses.

Not all do.
My 16"x24' floor trusses have are attached to a single 2x12 (ledger) on one end and supported by a wall on the other. They have a key on the ledger end where I'd just set it there to move it around and then secure it. Couldn't find the pictures, hope I didn't loose them.

BTW, anyone know how he's getting these dirt bikes up there?

Ramps!
Followed with Youtube videos.

Edit:
The ledger and trusses are attached with probably 100 Headlock fasteners.

 

[mike93lx]

Header/ledger could go either way? You have truss headers that span 8-12 feet and support the roof load. Ledgers not so much? Definitely no on the nails. I wouldn't use nails on the truss header either even though many builders do. Where it attaches to the post he could run vertical supports down to the floor as wheel.
.

Big difference, AFAIK. Headers bear on members directly, a ledger attaches to the face of members.

I would want the weight carried directly down to the foundation, as you would do with any header supporting a load bearing wall

 

[GMCGarage]

This is false information,please consult an engineer or architect....
fyi:A PSL starts @ 3-1/2"....you are speaking about a LVL they are 1-3/4".

Do not expect anyone here to spec a beam for you on here.

It would be a special order. Its the most economical if looking at section alone. I dont think they are in the tables.

 

[Diesel Dan]

Big difference, AFAIK. Headers bear on members directly, a ledger attaches to the face of members.

I would want the weight carried directly down to the foundation, as you would do with any header supporting a load bearing wall

Every pole barn I built they referred to it as a truss "header" and it was only attached by fasteners. Poles were not notched and no support directly to the ground.

Over 30 yrs later still standing in snow country.
Maybe it's just been mis-labeled and is actually a truss ledger?

As I mentioned before, my whole second floor of the living quarters is held up one end with a ledger. And that was the truss company engineers recommendation.

 

[scottydosnntkno]

We are fighting some "terminology" issues ! I believe what the OP wants is a beam that spans 20' (without intermediate supports) and that he can then run joists from a ledger on the back wall to the beam.

The way I read page 5 of Eastern BCI and Vers-Lam Builder Guide that beam would have to be at least a 6x16 LVL ! A steel beam might be cheaper and actually lighter ! Lally columns would be required at each end. Also these columns need to rest on a "full depth" concrete footing, not just the floor.

Joists should rest on top of the beam or be attached with proper brackets (NOT simply toe nailed). A ledger along the back wall for the joits to rest on is questionable. If that wall is just a 2x4 stud wall, the ledger should be supported down to the floor with edge-wise 2x6s, 24" O.C.

Page five is referencing a beam supporting the entire building width. So in that case a 20’ building width, the beam is carrying 10’ of floor each way. So if you want 20’ between supports holding 10’ then you need that big beam

But the OP is talking about carrying half of a 10’ span(so 5’) with a 20’ support distance. Which that particular chart doesn’t even go that low of sq ft area

The easiest way would be to use high strength floor joists (2x4 chords instead of 2x3) or floor trusses ran the long way. Either one can bear on the lower wall like a normal platform framed house. Or if the OP is balloon framing, they can bear on jack studs where needed.

No special tools, calculations, etc. just a clear span you can build the way you do the rest of the building. No point loads, footers, etc. it’s the same way millions of houses are built. Floor joists or trusses resting on a wall on a trench/spread linear footer

 

[scottydosnntkno]

Imo steel is a choice that needs some second guessing.

- any connection to wood has to be analyzed, fabricated, usually involves stick welding and/or drilling large (> 1/2" dia) holes for structural bolts.
- someone has to cut the beam to +/- 1/16" of planned dimension. Not a thing that can be done with a circular saw.

All of that takes more time and capability than working with LVLs which can use adhesives, structural screws, nails, and cuts with a circular saw....just like regular wood framing.

No inspector is residential construction gets down to, nor are houses built to that level of detail.

Every single house uses some amount of steel beams to support the first floor.

We measure the pockets after the walls are poured, and order our beams 1.5” less then that distance. Beams usually require 4” of bearing area on concrete walls, and our pockets are 6” deep so we have plenty of leeway.

And the connections, all we do is use a 2x6 laid flat, with 16d sinkers Nailed in the end an inch and hammered down and around the beam. Then your joists rest on top of that and are toenailed to the wood. There’s no fancy connections. If your doing a flush beam, it’s the same thing. There’s hangers that get nailed over the top of the flat wood and hang down to hold the joists

 

[theoldwizard1]

Pretty sure he is going to go with 22' floor trusses now. If he does the truss build one end will be sitting on a wall and the other will just need a header along the barn wall.

The wall the one end is going to be sitting on top of needs to have a full foundation underneath it, not just a 4"-6" concrete floor. A header/ledger attached the the other wall not adequate. That ledger needs supports going down to a foundation.

 

[scottydosnntkno]

It would be a special order. Its the most economical if looking at section alone. I dont think they are in the tables.

Weyerhaueser can resaw a 3.5” to a 1.75”. They have tables for them and yes they are special order. But it’s also the only way to get a treated structural wood beam for exterior use as well.

To just blanket say ‘wrong’ is ignorant just because he’s never seen or specd them before

 

[scottydosnntkno]

The wall the one end is going to be sitting on top of needs to have a full foundation underneath it, not just a 4"-6" concrete floor. A header/ledger attached the the other wall not adequate. That ledger needs supports going down to a foundation.

I imagine he has some type of footer since every state requires some type for anything bigger than a shed. A building with a 20’ span is definitely big enough.