# 12' desk span?



## gizzygone (Jul 26, 2012)

I'm building an office in my basement. I was thinking of just using a 12' long Laminate countertop as the desk surface, but I really want to eliminate any mid-section support. 

I don't think a 2x4 ladder frame will provide me the span, so I got to thinking a metal ladder frame would do the trick...

But, that's where my knowledge ends. 

Does anybody have any ideas? What would a frame like this need? Or cost?

I even thought about maybe using black iron pipe (since I dont weld).


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## SeniorSitizen (Sep 10, 2012)

gizzygone said:


> I'm building an office in my basement. I was thinking of just using a 12' long Laminate countertop as the desk surface, but I really want to eliminate any mid-section support.
> 
> I don't think a 2x4 ladder frame will provide me the span, so I got to thinking a metal ladder frame would do the trick...
> 
> ...


Go to your home center and ask to test one of their 24 ft. aluminum extension ladders. Open it the full 24 ft., block the one half length that's on the floor up 1/2" on each end and stand in the center. Now ask the sales person if the pencil you placed under the center of one rail can be easily removed. This will give you an idea of how much deflection it will have. But of course you'll be using both halves side by side.

Wooden ladder? May work if you build a torsion box


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## mako1 (Jan 7, 2014)

Why would you need a 12' desk top with a clear span under?Why not buy a couple cheap drawer boxes and have some storage while supporting the top?


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## Daniel Holzman (Mar 10, 2009)

The load on a desk is typically very light, unless you plan unusual activities on top of the desk (I will leave the ideas to your imagination). If all you are going to do is write on the desk, and maybe put a few computers on there, total load could be less than 200 lbs (that may be generous, assumes some heavy printers etc. For example, I have 12 feet of desk in my office, all it holds is a few computers and a printer, total weight less than 100 lbs. Course if you plan to put books up there, totally different story.

In any case, add up all the things you want to put up there. Include possible live loads (for example do you want the ability to stand on the desk). Then divide by the total area, which in your case is about 24 square feet (assumes 2 foot wide desk). Notice that even at 200 lbs, total load averages only about 8 pounds per square foot, very light. At that load, you could certainly build a 2x4 foot frame to support the load with limited deflection, maybe you would need (4) 2x4's the long way to support the laminate.


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## mako1 (Jan 7, 2014)

Daniel:I understand that you are a civil engineer and probably much smarter than I but a 12' long by 24" deep countertop /or desktop with a simple 2X4 frame on the outer edges with a minimal load of 100 lbs. will not support itself in the center for very long.
It all may look good on paper but in reality just does not function well.


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## gizzygone (Jul 26, 2012)

The clear span is just for convenience. I plan on making it a mixed use space: computers, writing, and Maybe hobbies (model making, etc). 

I will likely use cabinets on either end to shorten the span (maybe down to 10ft or even 8ft). 

I know the counter itself will need support, so I'll need some sort of frame, and I would hate for it to come tumbling down: should somebody decide to get a little x-rated down there... Or worse, if somebody were to use it as a changing table or something. 

The ladder doesn't seem like a bad idea, aside from the cost.


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## Daniel Holzman (Mar 10, 2009)

Mako: Just for a thought experiment, I did a few calcs on a 12 foot long, 2 foot wide desk with three 2x4's running the long way spaced one foot apart (in my post I suggested (4) 2x4's). I assumed 10 pounds per square foot live load (total of 240 lbs of stuff on top of the desk, relatively uniformly distributed), and 5 psf dead load (includes weight of framing and laminate).

I assumed structural grade framing. The factor of safety against bending comes out to 2.84, very favorable. The maximum deflection at the center under load comes out to be about 0.15 inches, which is probably acceptable. I realize this is theoretical, as I have not built a desk like this, but every significant structure in the world is designed based on theory, and they usually work out OK. Not sure why you think the desk would fail in the middle.


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## mako1 (Jan 7, 2014)

Daniel: I do respect your opinions and knowledge on this board .You help a lot of people but as a cabinetmaker and remodeling contractor for 40 years I always question the numbers.This would sag in the middle before long IMHO.your calculations don't take in the nature of construction lumber today and the moisture content and and a few other variables from the real world.I do respect your knowledge but have dealt with these things long enough in the real world to know the difference.


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## gizzygone (Jul 26, 2012)

Would angle iron have any support for such a span? 

What about 1.5" black iron pipe? Maybe if I filled it with concrete?


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## Bondo (Dec 8, 2007)

> I was thinking of just using a 12' long Laminate countertop as the desk surface, but I really want to eliminate any mid-section support.


Ayuh,.... Is this an off the shelf boxstore sawdust board supportin' the laminate, or is it got plywood for strength,..??

I'd think 3, 2x4s lengthwise would support a small car, muchless a desk top,....

Use big 90° steel angle brackets along the wall to support that side, 'n a couple 2 drawer filin' cabinets under it,....

Which is how My dumpster found corner plywood backed laminated countertop/ desktop is held up,....
4 big corner brackets against the wall, a cheapo imported oak 2 drawer file cabinet on one end, 'n a cute little antique dumpster found 3 drawer, slide out writin' surface, real oak cabinet, that I built a spacer on top of(bonus 3"x 18" slot/ shelf) to bring it up to the counter/ desk,...


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## SeniorSitizen (Sep 10, 2012)

If there is a corner available, a couple of 2-0 6-8 hollow core doors with a 2 drawer file cabinet to support the ends and a triangle filler / support built to fill the inside corner. That triangle area is for mostly decor like the kids pictures, your mother inlaw or MIL to be etc. I better leave the decor to someone else. Help me gals. Where is Starting over when ya need her?


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## gizzygone (Jul 26, 2012)

Yep... It'd be one of those sawdust cheap counter tops the big box stores stock. I'm looking for a budget build here, but looks like I'm in for an expensive project. 

I just wish I could weld.... And i could make some custom frame to lay on a 2x4 ledge


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## gizzygone (Jul 26, 2012)

Since I have the attention of a few engineers: can I try a few more options?

1: would a fiberglass u-channel provide enough support?

2: what about just making my own "butcher block" like desk, using 12' 2x4's, glued and screwed together (I'd elimaye the laminate top, and just sand and urethane the wood). Or would that also just sag?


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## mae-ling (Dec 9, 2011)

Ifg the 3.5 or 4" top is not to thick then yes your 'butcher block' idea should work. I would put a laminate top on top of it though for durability.

I would consider supporting the back and sides with boards on teh walls, maybe sides on cabinets or whatever. Then along the front use 1.5" square tubing, maybe 2 of them side by side. these would sit on posts at the ends maybe.


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## SPS-1 (Oct 21, 2008)

mako1 said:


> Why would you need a 12' desk top with a clear span under?


 Why does anybody need a 6000 pound Hummer to drive to the grocery store? Because we can.

But back to the op's question---- can you get a hold of a couple of pieces of 3 x 3 x 1/4" angle iron ? If you can manage to properly support the angle iron, you could stand on the center and it would barely move (200 pounds .08" deflection on 2 pieces of 3x3x1/4 angle back-to-back)


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## gizzygone (Jul 26, 2012)

I was looking at a website called metals depot. It has some interesting options. 

I just wish I could compare the strength of them all


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## mako1 (Jan 7, 2014)

gizzygone said:


> Would angle iron have any support for such a span?
> 
> What about 1.5" black iron pipe? Maybe if I filled it with concrete?


 What are you thinking about?I thought your OP was about a desk top?Concrete would do nothing to support a 1.5" steel pipe to begin with.Why not just use a tried and true wood structure that will work for your application?


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## gizzygone (Jul 26, 2012)

Just brainstorming ideas is all. I know black iron pipe to be fairly strong, but I wasn't sure if it was load bearing. I was thinking concrete may stiffen it up, such that I could make a black iron pipe frame for the counter top material. 

But, I know concrete has more compressive strength than torsional strength. 

The problem with traditional wood framing is bulk: To span the whole distance I'm guessing I'd need 2x6 framing, plus the thickness of the counter top. 

If I could afford a welder, I'd likely try to teach myself how to weld a steel ladder frame... But the cost is prohibitive.


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## 123pugsy (Oct 6, 2012)

I make desk supports on a regular basis at work for commercial office furniture.
A 2" square tube with a 1/8" wall running across, a few inches from the front and back edges so it's less noticeable should do it. Drill holes thru it and use long screws to screw it to the underside of your desk top.

The key though is to support each end and lightly "bounce" on it to give it a slight crown so that when it's all done including the wood top it sits flat and true. Crown the tubes before screwing them to your top of course.


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## mae-ling (Dec 9, 2011)

No need to weld. Us eangle brackets and screw the metal that goes across the front to your posts on the sides that are under the two ends of it. 
I suppose if you had a welded frame you could just anchor it to the wall and maybe not need posts. If you do not want posts/support at the ends talk to a welding shop about welding it for you.
Or - - - better yet buy a new toy and watch you tube videos and learn to weld. New tools are always good option!!!!!!!!!!!!!


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## gizzygone (Jul 26, 2012)

123pugsy said:


> I make desk supports on a regular basis at work for commercial office furniture.
> A 2" square tube with a 1/8" wall running across, a few inches from the front and back edges so it's less noticeable should do it. Drill holes thru it and use long screws to screw it to the underside of your desk top.
> 
> The key though is to support each end and lightly "bounce" on it to give it a slight crown so that when it's all done including the wood top it sits flat and true. Crown the tubes before screwing them to your top of course.


You think 1/8" wall is enough? And would I need just two lengths of tubing? 

How much weight do you gather it would support?

The entire rear would be supported by a 2x4 bracket nailed to the wall to rest the counter on


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## ChuckF. (Aug 25, 2013)

You could adapt some of these to your 2X wall structure:










http://unisourceparts.com/p/49/herman-miller-support-arms


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## gizzygone (Jul 26, 2012)

ChuckF. said:


> You could adapt some of these to your 2X wall structure:
> 
> 
> 
> ...


It's funny. I was looking at the Elfa track system last night and thinking the same thing, but the cost was astronomical.

I'll have to look Into that a little more. If I can find a wall mount system that's more affordable, I'd much rather go that route.


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## 123pugsy (Oct 6, 2012)

gizzygone said:


> You think 1/8" wall is enough? And would I need just two lengths of tubing?
> 
> How much weight do you gather it would support?
> 
> The entire rear would be supported by a 2x4 bracket nailed to the wall to rest the counter on


If you have a 2x4 cleat on the wall already, you are only supporting half with the tubes, so yeah, the 1/8" wall would be fine.

2-1/2" square would be a lot better if you have room for it.


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