Marble dining table help please

[Adam Herman]

great advise.

I would also go with a construction similar to the picture posted earlier. my father and I built a large version of this about 6' x 12' for a model railroad setup. 1.75x 5.5 oak aprons, 5 in sq poplar legs with the corner braces and 3 lags per leg on the diagonal as shown. the top was lighter, but maybe not by much with all the 0-gauge trains, the bridge, buildings, transformers, etc. top was 3/4 baltic with 1x4 oak rails around the edge and a "rung" at each plywood joint. about 11 feet of span between the legs and no sag whatsoever. that table has been around about 20 years now and is still flat as ever, I think it may qualify for some kind of flatness spec like a surface plate.

I think you have a good plan even if the slab weighs more like 400 lbs. I would add a center "truss" of a slightly taller dimension, could be solid or a couple thicknesses of ply glued, and about 3 ladder rungs in the frame. no ply infill, not necessary and does not really add any structure. I think dominos would be great.
I/we often way overthink stuff like this.

[Ollie McDottie]

A big thanks to all of you for your insights. Started project yesterday. Will post pics in a week or two when it’s done. The kindness and helpfulness of the folks on this site never ceases to impress me. You all the best.

[Rob Burch]

I don't think the table I made is as big as the OP was thinking about. Mine has a top about 63" long and maybe 32 wide (intentionally narrow per the wife's instruction since our dining rom is smaller). The top is granite and it is simply "stuck down" with silicone
Frame is red oak.

It has been in service for 3 years with no issues and we have moved it around a few times. No sign of flexing and cracking.

[Aiden Pettengill]

As someone working in the stone fabrication industry, the most important thing is making sure there is NO sag what so ever. Granite will flex some but marble is very brittle and will snap especially if its 2cm vs 3cm. Experience sucks! (I've broken my fair share of slabs!) Not really something you want when marble can run up to $180/sq ft for Calcutta Gold. Nice looking table Rob too!

[Rob Burch]

Thanks Aiden

My wife is pleased with it and she gets the only vote cast. It was the second piece that followed the beverage center you see behind the table.

You know how it goes.....built the beverage center and the minute it was installed..."I want a table to match".

This has now precipitated phase three which is a cabinet re-do. She was not happy with the timeline I was on so she want and had new granite (to match the table and the beverage center) and new backsplash tile. My part is new shaker style doors and a host of new drawers and slide out shelves followed by a re-painting of the cabinets. I am on the clock now.

My solution was different in that I would have started with a sledge hammer and ended up with all new stained wood cabinets. I lost that decision in a landslide on a 1-1 vote.

To the OP.....Did not mean to hijack your thread.

[Ollie McDottie]

As someone working in the stone fabrication industry, the most important thing is making sure there is NO sag what so ever. Granite will flex some but marble is very brittle and will snap especially if its 2cm vs 3cm. Experience sucks! (I've broken my fair share of slabs!) Not really something you want when marble can run up to $180/sq ft for Calcutta Gold. Nice looking table Rob too!

Thanks for this. When you say sag, do you mean in the middle or along the edge where the marble might overhang the inset apron by an inch or so? For the middle I'm building a torsion box of sorts to support the weight of the marble. Two supports running the length 12" apart with perpendicular lateral supports between them about every 21".

[Aiden Pettengill]

Thanks for this. When you say sag, do you mean in the middle or along the edge where the marble might overhang the inset apron by an inch or so? For the middle I'm building a torsion box of sorts to support the weight of the marble. Two supports running the length 12" apart with perpendicular lateral supports between them about every 21".

You want to be sure that the bracing and frame won't flex with the weight. From the sounds of it you should have plenty of bracing! So long as there isn't a high spot you should be good. Good luck and share pictures!
Aiden
ps. don't worry about the overhang! With 3cm or 1 1/4" thick stone (measurement systems vary depending on where the slab was cut) you usually can safely overhang 6" without support.

[Ollie McDottie]

A big thanks again to all who jumped on this thread with all of your excellent suggestions. Thought I'd share some pics of the base now that I've finished it. Again, so grateful to this forum and the insights of you fine folks who very much informed my construction. You all the best!!!



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[Tom Bender]

Ollie
You have built a nice ladder frame. It should provide enough support. Just a couple of concerns;

A torsion box would have protected the marble from twisting should the table be placed on an unflat floor or be lifted unevenly. I would not be comfortable with the risk you have created.

The leg to apron joints look suspicious. When the table is dragged those joints could fail catastrophically and crush the dragger.

I would follow advice given to adhere locator strips to the marble with hot melt or silicon.