Creativity, Practicality, or Heresy?

[John A. Schaefer]

I'm going to be building a "Contemporary" Mission / Prairie style desk for my office. I'm finalizing the design right now, but it's basically going to be a large desk surface (72" x 28") with no drawers or storage underneath. I'm planning to go traditional and use red oak for the base. The Visio drawing below gives you the general idea.

161606

Now, here's the potentially heretical part. Instead of using wood for the work surface, I'm seriously considering granite. :eek: The desk will be used for a couple computers, as well as for writing and sketching on paper. (I think my cat will also appreciate laying on the coolness of the granite.) I think that the granite will give me a better overall surface and provide several lifetimes worth of service. I'm concerned that if I build the top out of oak that I'll also need to put glass over that in order to give me a usable surface that won't be easily damaged.

So, is this just crazy? This will be by far the biggest piece that I've built to-date, and it's my first time working with red oak, so all comments, thoughts, feedback, or alternative ideas are appreciated.

[Thomas Bank]

I like the concept, but I'd run the concept past the people you'll be buying the granite from. I have a feeling they'll say something about the slab only being supported in the corners. Very easy to crack/snap an unsupported stone slab.

[John A. Schaefer]

Thomas-
Thanks for reply. You raise a very good point. I was planning to support the granite with 1/2" ply (the dotted line under the top in the drawing), but I will need to confirm all this with the granite yard just to be safe.

[Jamie Buxton]

Thomas-
Thanks for reply. You raise a very good point. I was planning to support the granite with 1/2" ply (the dotted line under the top in the drawing), but I will need to confirm all this with the granite yard just to be safe.

My mind's eye likes the look of that table. However,half inch ply of that size offers almost no support in the middle. Get a sheet, support it near the ends, and put your hand in the middle to flex it. You'll see it doesn't take much force to bend it enough that the granite is at risk. I'd put something more like 1 1/2" thick solid wood (not plywood) under it.
Of course, if you're putting a solid lumber subtop on the piece, you could just as well lose the granite, and declare the lumber the desk top.

[Thomas Bank]

As Jamie says, 1/2" ply isn't going to do anything to support granite. A 1 1/4" slab weighs about 20 p.s.f. A 2" slab weighs about 30 p.s.f. So you're talking 280 to 420 lbs. for just the stone. And granite is brittle.

They'll typically use a 3/4" ply sub-base for granite countertops. And that is supported by the base cabinets - not clear spans like your desk. Even the base cabinets are beefed up as they get wider. Unfortunately, your desk is going to start to look more like timberframing than Mission/Prairie at that point! :)

[Paul Murphy]

The granite would look beautiful, but might be uncomfortable to rest your arms on. That would be one very effective heat-sink!

Red oak is a pretty hard wood, and I doubt you would do it any damage in an office setting. I have a “counter-top” of red oak over my shop cabinets, and it still looks great after 5 years of workshop life. You could fill the grain on a red oak top for a more formal look, and red oak is fairly stiff so it would perform well even unsupported in the middle. I think a top made from 6/4 stock would be pretty rigid.

Either way, your desk will look beautiful.

[Mark Valsi]

Although it will look great, I think you will find that you are sorry you didn't include drawers and closed off storage space of some kind

[Tom Walz]

Really like the design.

Not sure how much adding the the support for the top will change it. I am not sure you can do it with just a sheet of plywood and no further supports.

[Nathan Allen]

Easy: Throw a blotter pad down
Medium: Create 2" thick support stretchers around the perimeter, increase the size of the four corner posts and M&T all of them together
Hard: Torsion box support the entire top, provide a loose fit false front around the perimeter. Granite sits on top of the torsion box, torsion box on top of the four corner posts.

Like other responses, that granite is going to be heavy, at the very minimum you'll have to support it to distribute the weight

[Chip Lindley]

I really like your granite idea! Supporting it successfully will be your biggest design challenge. Keep us posted as to what the Granite People say! If they poopoo your idea, perhaps Corian could be employed to give the look, yet save save on weight, and add a bit more forgiveness to your design.

[Greg Portland]

Instead of using wood for the work surface, I'm seriously considering granite.You should be able to figure out a way to support the slab effectively. However, a bigger problem would be the use of ball point pens on granite. With thin paper I've found that that the pens do not work very well (not enough friction to roll the ball and get more ink). A blotter pad would solve this problem but might not be the look you're going after.

[Neil Brooks]

Two cents more....

I love the idea, but ...

When our house was built, the builder neglected to put corbels on the island, to support the roughly 2-1/2" thick granite top, as it hung 18" OVER the island (to get chairs and knees underneath) for a 4' run, on two sides.

[Still with me ? ;)]

The granite people were clear: do NOT use the island until the free span gets corbels installed, underneath. They insisted that granite DOES have a propensity to crack, and that that's about its only weakness.

I can't speak for your particular design, but ... wanted to second the notion that you probably SHOULD get some input from people who make their living engineering and installing granite.

Good luck !

[Mark Rakestraw]

I'll just chime in to agree with the need to support the granite. I've used solid surface (Corian) on tables and buffets and it will also need support, not as heavy but much more saggy. I would be thinking about using a 3" skirt board all the way around for support. A drawer would be nice, but then of course the skirt board would no longer be structural.
Mark

[Brian Tymchak]

I'm concerned that if I build the top out of oak that I'll also need to put glass over that in order to give me a usable surface that won't be easily damaged.



Instead of glass, maybe you could put a clear epoxy coat over the oak. I've never done it myself, but I've seen some really nice looking bar tops.. :rolleyes:


http://liquidglasscoating.com/?gclid=CIf8yv25lqQCFQlm7Aod1Hxn3g

[Jamie Buxton]

Instead of glass, maybe you could put a clear epoxy coat over the oak. I've never done it myself, but I've seen some really nice looking bar tops.. :rolleyes:


http://liquidglasscoating.com/?gclid=CIf8yv25lqQCFQlm7Aod1Hxn3g

Ick. Wood is beautiful, and can be very durable. Thick plastic is just ugly.

[Stephen Cherry]

How about white oak, instead of red?

[Bart Leetch]

I like the idea too, but lets talk about moving it if you need to.

Personally I like it but it doesn't sound very practical.

[John A. Schaefer]

WOW, has this taken off...:) At least no one's called me a heretic yet...:D

I still haven't given up on the idea of granite, BUT according to the granite fabricator there is no way that the design as shown would provide enough support for the stone.

But he did have some interesting ideas. As we're all woodworkers here, that's where we've been thinking for solutions. He suggested looking at steel as a support. While I don't think that a big steel plate would be very practical (to Bart's point about moving this in the future), Nathan's comment about a torsion box got me thinking of a steel tube ladder frame. So I'll be talking to a welder to get her input.

There's also a local place that does granite counter "overlays." You've probably seen ads for places that will "update the look of your kitchen or bath in a couple days." The pictures of their stuff doesn't look all that great, but I'll be going to their showroom on Saturday to see it in person and run this idea past them.

But I've also been looking at my lumber options (just in case). There's a local sustainable farm that has a lumber mill and takes trees that have come down in storms. I'm hoping to take off early one day this week and go take a look. They claim to have rough cut slabs up to 6" thick x 12" wide, although I'd only be looking at the 2" or 3" stuff.

I don't really want to compromise the design just to get the granite. I want it to look like the top is only supported by the 4 posts of the legs. If I can figure out a way to support the stone with relatively thin steel support structure, that may work. Or the granite overlay, if it doesn't look to artificial. Otherwise, it will probably end up being all wood.

Thanks for all the great input. I'll keep y'all posted on what happens.

[Neil Brooks]

My GUESS is that ... you'll only get serious strength, using steel, if you use either an I-beam or (square) box configuration.

I'll be watching this thread, with interest, either way.

One other thing: you're a big, fat heretic :D

Just kidding :) It's a great idea. Hope you can pull it off.

In truth, our builder messed up the first go with our kitchen island, but ... gent that he is ... left the "goof" slab, behind, for us. I'm long sitting on that thing, waiting for the perfect woodworking opportunity that would use it as a topper.

Likely a sideboard, or .....

Good luck !

[Justin Bukoski]

I'm considering using paperstone for a desktop. I'm waiting for some samples before I decide. I think its quite a bit lighter than granite.

One other choice might be lightweight concrete.

[David Helm]

How about white oak, instead of red?
I agree with Stephen. Traditional Mission furniture was usually made out of quartersawn white oak. Much prettier than Red.

[Warren Clemans]

Heretic! There, I said it. Craftsman furniture is made out of wood and sometimes bits of metal, but not rocks. I like the deisgn, but I vote for sticking with wood. Even if you can solve the technical challenges of using granite, it doesn't mean you should. Save the money on the stone and invest in some nice wide boards for the top.

[Brian Kincaid]

Looked into granite for a dining room table. Do you have any idea what the top will weigh? It is a big number.

-Brian

[Greg Portland]

You will want to be careful with your granite selection. The grain pattern in QS oak may appear too busy with some granites (lots of colors and patterns). A very plain granite may work.

Since you already have this in Sketchup (or other CAD program) you should be able to slap some granite pictures / textures onto the top and see if it's visually appealing.

[John A. Schaefer]

Brian-
The granite guys said to figure 16-20 pounds per square foot for 3cm thick material, depending on the type. Since the desk works out to exactly 14 sq ft, I figured a worst case scenario of 300 lbs. That should give you some rough idea for your table.

Greg-
I have the drawings in Visio, which for me is the quickest (and easiest) product to use. (After having to draw some pretty detailed network diagrams for work, I think I've used about every feature in the product!) But while it can do technical drawings very well, it doesn't do so great with textures and photo-realistic content. I do have sample piece of oak that I've taken with me to the various granite dealers, and it has helped me limit the choices somewhat. One place had a granite they called "Galaxy Black" which is black with some light flakes throughout that really looked nice, but it's in their highest pricing tier. Surprisingly, uba tuba didn't look to bad.

[Ed Hazel]

Why not just put the Granite in the center where you will be writing ect?

[Brian Kincaid]

...worst case scenario of 300 lbs...

... uba tuba didn't look to bad.

Thanks for the estimate. That is helpful! 300lbs is not something that is move-able after install. Not good for furniture.

Uba tuba is VERY popular and instantly recognizable by anyone who has upgraded their counter-tops! (like me :D)

-Brian