Looking for design advice for built-in desk with long span

[Gary Oney]

Hello,
I am attempting to build a built-in desk and cabinet for my home office. The area I am constructing it on is a bit of a challenge, due to a 45 degree angle in the wall, along with two windows. Furthermore, I am hoping to do this minimal supports, because I have 4 monitors on my desktop, and I am hoping to avoid knee-knockers while moving around my workspace. The total wall distance is 12', with a 30" cabinet taking up space on one wall. I attached a couple of images I created with Sketchup for illustration. The wood would be Red Oak (plywood and boards), with the desktop surface being 3/4" MDF with a formica top.

The problem I have is that the lack of supports will likely sag the MDF top. I have limited support on the back wall due to the windows, and the total distance from the left wall to the cabinet will be 9'6". Wooden support runners seems inadequate, so I thought I might use steel instead by hiring a local welder to construct a frame for me to attach the desktop. My design involves 1" steel tube (square or round), bolted to the wall studs at each end with a floor brace on the left side and an angled brace about midway. I attached another Sketchup image to show my proposed solution.

Looking for feedback on the design and my proposed solution. Is the idea of a steel frame overkill? Underkill? Just plain stupid?

[Kenneth Speed]

It looks like the steel frame would work but I wonder if you're not opening a Pandora's box with it. Would the welder be able to make it fit precisely enough, would it be flat? If it needs adjusting, can you adjust it? I'd hesitate to go that route because I'm not a steel guy.

I'm not entirely convinced you need that much support anyway, I think you really need to support the counter top joint and perhaps run a small apron under the top for some added rigidity. The joint can be supported with a steel bracket or a wooden support shaped like an inverted L or with a metal tube ( chrome or brass) running between the floor and the underside of the counter.

Ken

[Gary Max]

Personally--- I like over built--- my desk top is 5 inch thick Hard maple. Would a leg between the windows be in your way if you moved it into the center?

[Jason Roehl]

I'd have your steel guy fabricate some brackets to go on every other stud underneath the desk. That 1" square tube welded perpendicular to 3/16" plate with a small angle support should be plenty adequate without impinging on your knee room.

For aesthetics and perhaps some function, I'd say that the left end needs less of an acute angle, perhaps even square it off.

[Harry Hagan]

A tapered bracket like this would work.

Bracket.jpg

[Gary Oney]

Thanks all for feedback. Some thoughts in reply...

It looks like the steel frame would work but I wonder if you're not opening a Pandora's box with it. Would the welder be able to make it fit precisely enough, would it be flat? If it needs adjusting, can you adjust it? I'd hesitate to go that route because I'm not a steel guy.

I gave a lot of thought to the idea of precision, but I think it can be done with reasonable accuracy. As far as adjusting, if necessary, I assume that I could probably make minor adjustments with shims in order to level the desk.

Would a leg between the windows be in your way if you moved it into the center?

Yes. Although I toyed with the idea of a leg against the back wall, with a 45 degree brace 2/3rds of the way up, but that would not solve my problem with potential sag on the free-spanning area of the windows (where I have no support in back either). The windows are roughly 42" wide.

For aesthetics and perhaps some function, I'd say that the left end needs less of an acute angle, perhaps even square it off.

That bugs me as well, but I did not want to square it off where a corner of the desk is in the middle of the window. The reason for the angle is that the wall where the desk ends has a door that limits the space in order for the door to open fully. Thus, if I go further, the door will bang into the desk. Although I can obviously solve this problem with a door stopper, it creates another aesthetic problem due to a half-opened door. Nonetheless, I have not yet reached a conclusion which way I would rather go - it changes daily.

I did make one change to my plan. I realized that I do not need to go all the way to the wall on the right side, but I could end the steel runners at the cabinet, which should make construction a little easier. See attached pic, which also provides a better view on the angled bracket. If I go this route, I would cover the angled bracket with Red Oak trim, so none of the steel would be visible unless someone crawled under the desk.

[Dale Cruea]

I have to wonder what it will look like from outside.
Also, make the steel frame in 3 pcs. The left side, the wall bracket and the right side.
Add short pcs of tubing or solid pcs of stock to the wall bracket that will slide inside of the larger tubing.
Also consider the wall thickness of the tubing. I don't think thin wall tubing will work well here.
Keep in mind the mounting holes to be drilled into the tubing. The location and size.
This will weaken the tubing some. Keep the size as small as possible and the location as close to the ends as you can.
You may want to consider angle iron with a piece welded along the open face. This can be very strong but heavier than tubing.

[Gary Oney]

I have to wonder what it will look like from outside.

See attached picture, if you can get past the rather disorganized nature of Sketchup as I did not bother to recreate the finished look of the outside of the house. The windows have horizontal blinds, so the real view would not be as clear looking in as the Sketchup image makes it appear. Note that I included a 2" Red Oak apron around the edge facing the window. If you look at the earlier picture of the desk from above, I made a 2" indention from the wall at each window, both for aesthetics and since doing so will effectively take the place of grommets for monitor cabling.

Also, make the steel frame in 3 pcs. The left side, the wall bracket and the right side.
Add short pcs of tubing or solid pcs of stock to the wall bracket that will slide inside of the larger tubing.
Also consider the wall thickness of the tubing. I don't think thin wall tubing will work well here.
Keep in mind the mounting holes to be drilled into the tubing. The location and size.
This will weaken the tubing some. Keep the size as small as possible and the location as close to the ends as you can.
You may want to consider angle iron with a piece welded along the open face. This can be very strong but heavier than tubing.

Good suggestion on the use of variable sized tubing as a means of adjusting the size. I'll consider that when talking to the welder. I had planned to use 1" square tube with 1/8" walls, but I'm just guessing that it would be adequate. I was not planning to drill mounting holes - instead I planned to use brackets that wrap around the tube, then screw to the MDF. Aesthetics on the mounting are not that important since it won't be visible anyway, and that way the tubing retains full strength.

[johnny means]

Google work station bracket. We use them all the time in commercial and institutional settings. Use as many as you want, plenty of knee room. Some of them even have holes for wire routing.

http://www.cshardware.com/fastcaps/fc-sb21x24wh.asp