I'm bidding on a conference table for a local company. They would like a 4' wide by 12' long table with a couple of box leg bases. Top will finish around 1.5" thick.
I'm having difficulty finding 13'+ long boards to make it out of. I'm considering either end gluing boards, kind of like a hardwood floor, or running the boards across the width so I only need 4' long boards. If I go widthwise though I'm worried about wood movement over 12 feet and how that night affect the bases which are connected by a double trestle under the top. I calculate 1.6" of movement in the Midwest where I'm located and this seems like way too much to handle even with clips attaching the top.
Any thoughts or suggestions?

13' stock is available, but generally at a premium. If the customer is expecting continuous runs, then bid the job based on the cost of the material. If the cost is above their budget, offer the alternative of butt joints which would be somewhat less expensive. Building the table out of 4' shorts as opposed to long lengths would be a disaster in my opinion, you'll have end grain showing all along the edges and it will not be attractive.

Feel them out for their budget and see if you're able to meet their expectations and make a profit, otherwise make a bid and be prepared to walk away. That table, properly constructed, will not be cheap.

There is a reason one almost never sees a solid wood walnut table 12 feet long. They are usually veneer over MDF or some other substrate.

A table with the boards running width-wise might work, I have seen some, and they are not ugly, but once again, there is a reason one doesn't see them every day,

Splitting it into two 6' tables that meet in the middle is one approach - makes production and moving that much easier, and in theory, one can find nice 6' walnut boards much more readily than any 13 footers.

I helped build some solid walnut tables about that size for a university law library.The tops were made from 6/4 walnut, #1 Common grade, with a "rustic" finish.
The owner of the shop couldn't find any 12' long walnut locally here in the Midwest. The walnut he did find was very expensive.He contacted a mill in Tennessee, who did have some 12' long stock. He found that it was actually cheaper to buy it from the mill, rent a truck, and drive it back.
He found the mill through Woodfinder, so I would suggest you try them also.
Good luck with your project!
Rick W

Not a criticism but when I saw the 1.6" my mouth opened so ran it through my wood widget app and at extremes flatsawn walnut 48"w @ 80% @ 100F down to 35% @ 70F yielded -1.091" so you not completely off but any shrinkage over and 1" bring ups a Seinfeld laugh.
I have also had the fortune to do 3qty live edge walnut last couple years- 2 that were those sizes and the slab prices were reasonable but went through local small dealers and two were air dried w major checks that were bow-tied and resin filled. Just make sure you have a pin moisture meter handy.
For budget minded clients you might suggest 5/4 glue up infill with 8/4 long grain edging with 8/4 bead board ends which keeps cost & weight down and keeps it flat? Have not done this in walnut but a couple oak lately.
fyi - My website has been having issues lately, so if your not able to get thru you not the only one!

If we do one that size we use 1.5" mdf for the form with a walnut veneer and solid walnut edge. You can order some very nice grains from Certainly wood and have it laid up.

Thanks for the notes. To clarify, the 1.6" was over the 12' if I ran the board the short way. With normal midwest numbers, I only get .5-.6" over the 4' width.

The customer doesn't want veneer as they are buying this table to replace a veneer one that has fallen apart. Appears they just hired someone who didn't know what he was doing for the original table, but they're stuck on solid wood.

I thought about a breadboard end, but at 1/2" of movement, I don't think this will look too good. I can handle the movement in the construction no problem, but the appearance of 1/4"+ sticking beyond, isn't too appealing. This would actually be my preference as wood would be cheaper and the added end support would be great.

I found 12' stock, but figure I'll only get about 11.5' out of it after trimming. I was able to find slabs that were 14' that I can rip down and have a lot of waste though. I'm planning to present to them an 11.5' table and a 12' option with the 12' option being about $3000 more due to the wood.

I'm also presenting a 12' option with two 6' pieces joined in the middle. Not as appealing, but much easier to move around for me and the wood is far cheaper too. I figure a couple of large T bolts will hold it and I have a third middle leg already due to some media they want run from the floor through the table.

Maybe a design change that will help to hide the movement , if you design the top with bread board ends that are wider than the top maybe enough so when the top shrinks or grows you still have a wider bread board end .Look at Greene & Greene furniture they used a spline of contrasting color at this intersection as an embellishment as opposed to trying to hide it .

cabinet shop next to me asked for a large walnut top from me. i priced lumber to bid but found lumber liquidators offered 25 x 144 butcher block tops for a fraction of what my wood cost was. true not a custom boardroom quality conference table, but he bought 2 tops cut joint on his slidèr glued together to make his 4x12. he was happy.

Butcher block or cutting board? I would guess the latter, the difference being that true butcher block has the end grain up.

Actually, I think that might make a very good looking table. Since the long grain would be vertical, over the 12' length of the table there would still be considerable seasonal movement, but that can be managed with proper base design.

IMO a top that big out of solid is wasteful and foolish no matter how you slice it. If they have a hang-up you need to educate them. What about having a pro lay-up with 1/16th walnut veneer. Might be a compromise.

It is wasteful to make a table out of wood? You are kidding, right? You know that wood grows on trees and there are 3 trillion trees on the planet, right? And this is "Woodweb", right?

Which reminds me - I need to sharpen my chainsaw - they aren't going to cut themselves down...

I meant wasteful money wise. Also consider the weight. But if that's what they want....

I am sure the buyer appreciates you looking out for his budget, but that is his concern, not yours.

Be concerned about this. #1 you gotta source that timber Difficult. #2 You have to glue line rip large planks. Nightmare without heavy equipment. #3 you have to glue it up and figure out how you are gonna plane something that big. Does Jason have a 48" anything? Do they even make anything that big?

A CNC would do the trick.

So, I did mean breadboard ends in my above post not beadboard, my bad.
On the straightline rip - I have had great glue joints w Festool track saw especially with the secondary glue-ups that are to big and cumbersome to pull off w/ a joiner - tablesaw combo. So gluing is a matter of clamping and clamping flat. I don't see a problem, besides the last glue-ups are so wide you would card scrape, hand plane and sand anyway with dominos spaced on 8-12" centers, no biggy. Thick veneer would be OK but your trading labor for materials at that point if you doing it right with balanced panel construct. Depends on the client and usage, I've seen too many veneer tops gouged beyond reasonable repair, hope you have a good burn in kit.

Thanks everyone for the help.

Turns out the customer thought they had a 14' deep service elevator that was really only 10' deep and so the answer was pretty simple in that the top was going to have to be two pieces. Kind of unfortunate as I was really liking the bread board design, but this will work too. Will end up with three legs so the center leg can support the two pieces joined together with T bolts.

I would have used a festool jaw to rip the boards if I went with 12' boards, but with just 6' ones now, I'll use the jointer. Dominos work great to bring it all together and I have a 25" planer so I only have to worry about cleaning up one glue line and with dominos and doing it right, it shouldn't be more than a few thousandths.

Getting the two top pieces to match in the middle with the T bolts could be a little trickier, but with some time, I should get this very tight. If there are any tricks out there, I'm all for it though.

The three legs will be connected with a couple of 8" wide trestles that will hide the cables as well and I'll attach the legs to the top with those small metal table top clips to allow for movement.

Thanks again for the help and suggestions.