Building A 32-Foot-Long Conference Table

... and then christen it, "The Titanic." March 9, 2008

Question
I have a customer that wants a conference table that is 7' wide X 32' long! He wants a solid wood top, also. I am thinking about using 5" square legs that will be mortised for an apron around the table. Would 5 legs on each side be enough? Top would have to be in 4 sections to move, and I thought we would assemble legs and apron on site. It will probably be made of knotty pine. Any advice on this?

Forum Responses
(Furniture Making Forum)
From contributor H:
You do realize how much a piece of knotty pine that size will expand and contract? If a 20" panel moves 3/16", do the math. Advise your client against solid wood. Or make the table as several smaller ones that butt up against each other.


From contributor G:
If you have the entire top coated with a poured resin (top and bottom), would this stop\slow the expansion\contraction? They could pour it on site. They do a lot of commercial bars this way.

From contributor P:
Have you done anything like this before? If not, I suggest you sub it to someone who has. The approach you describe has a lot of problems, too many to go into here, but the expansion issue is real. Also to consider: a table this large makes its own microclimate in a room. The underside will experience very different temperature and humidity conditions from the top. Solids are very likely to warp or crack in this situation. You need to discuss these possibilities with the client, and see how committed they are to solid wood.

From the original questioner:
I've made many tables, but nothing this large. What would you recommend for the top? It is going to be covered, anyway, with a vinyl logo and glass on top of that.

From contributor W:
A 7 foot wide solid top made from flatsawn red oak will change width by 1-1/4 inches if the moisture content varies 5% (which is not an unheard of moisture swing). The same top made from flat sawn sugar maple will change dimension 1-1/2 inches. Glass covering won't change measurably. But the client promises to maintain strict humidity control, right? Right...

From contributor P:
If they put glass on it, kiss it goodbye. The moisture differentials between top and bottom will curl it up like a potato chip. Believe me: I've seen it happen to a 16' solid table. Humidity control in the room is a start, but it's the humidity and temperature differences between top and bottom of the table that will doom it.

From contributor U:
Tables this size really have to be engineered correctly by someone familiar with large panel construction. Asking us, while a good start, will not guarantee a sound final product. The expansion on this would be enormous, uneven and catastrophic if not managed correctly. Remember, nothing can stop would movement.

Don't even think about a full perimeter apron. Even breadboard end would move so much, it would look like the table fell apart. There is a place for veneer, and a place for solids. This is a candidate for veneer. You should come up with a very pleasing section design that visually flows, but can be made of many field-joined panels.

About the glass on top, that can do some serious damage. I saw a lawyer that did that to a 50k koa desk. Buckled the whole thing. Guess who he went after...

From the original questioner:
I made a lawyer a solid walnut table about 3-4 years ago. It was 1 1/2" thick top. He put glass on top of it and it still looks perfect. Might have been lucky?


From contributor G:
I still think you should look into getting it poured. Have the vinyl logo and stickers under the resin. Very durable and no moisture intrusion.

From contributor J:
If it is going to have a logo on the surface and be covered with resin, why start with wood? Use plywood with a nice veneer and avoid the movement issues. If it's going to end up looking like plastic, there is no need to use wood of any substantial thickness for the top.

From contributor D:
I agree with the cautionary tales above - this is not as simple as it may seem. As for the "pour it top and bottom" to prevent wood movement, I disagree. Nothing will prevent wood movement if the RH changes. Thick finishes will slow the moisture exchange some, but cannot prevent it. The finish will also have to move with this solid top. Think of this thing moving 1-1/2" - can any finish be that flexible for long?

From contributor A:
Forget the pour-on epoxy. You would be better casting the table out of epoxy and pouring on some wood. This table has to be engineered. I would imagine nomex honeycomb core/fiberglass skins with thick veneers. This is not a job for a slab of wood.

From contributor S:
The apron and legs would be okay if some sturdy rails (say 2.5" by 3.5" section) crossed them under the top and the top of whatever material was screwed down to them. The old masters kept the tops thin and the frames sturdy. The guy above who put glass on a half inch top got away with it for that reason. Any solid top over inch and half could have saw kerfs running the length of table, on the underside of course. Kiln dried and double checked moisture contents a must. Bang a pin meter into one of the doors in the room! Good luck... Or if you have none, use veneered MDF!