Replies

1. 
   woodrae | May 16, 2007 07:32am | #1

   Hgajr—

   Interestingly, we recently had to increase the height of an old oak pedestal table for a couple in town. Many older tables were designed and built for generations of smaller people, and for chairs with shorter seat heights, so it’s not uncommon to raise them to modern standards, which for casual seating and dining is between 28 and 31 in. For the job we did, we simply added a couple layers of 3/4-in. plywood under the top, using screws and glue for the joinery.

   I think you can do the same thing with your table, only you’ll need three layers of 3/4-in. plywood to create a height of about 29 in.

   As far as the diameter of the plywood lamination glued to the quartz goes, I confess that I’m not familiar with this particular material, having never worked with quartz. (Are we talking about solid quartz here? Is there a layer of fiberglass mat adhered to the underside to strengthen it? Or is this some sort of plastic laminate made to look like quartz?) If you’re working with solid quartz, I think the prudent move is to ask the stone people that are working your top what the maximum unsupported overhang for quartz can be. If they can’t tell you, call a local stone company that specializes in countertop fabrication. However, with as many stone tops that I’ve worked over the years, I would hazard a guess that the overhang could be as much as 6 in. or more. But you should definitely get a stone expert to answer this for you. Assuming you can go with a 6 in. overhang, that leaves a plywood diameter of 24 in. I would go ahead and cut the other plywood discs to this diameter, perhaps beveling the lowest disc so the edges aren’t prominent when seen from table height. If you have to have a smaller overhang, then make the first supporting disc to the specific size needed, and then make the remaining discs 24 in.

   With three layers, and a fourth counting your quartz/plywood lamination, you should still have plenty of knee room. The rule of thumb for knee space is to have an apron under the top that’s no more than about 4 in. wide. Your layers of plywood will still be less than that dimension. In fact, you could probably go with a total of five layers and still have enough room for sitters.

   Use the hanger bolts to attach the first two, gluing these two layers together first and then using nuts in counterbored holes to snug the discs tight to the column. Then simply glue and screw the remaining layers to the layers below. Finish up by screwing from below and through all the layers and into the single layer of plywood adhered to the quartz, using plenty of screws in countersunk holes. Screws every 6 in. or so around the perimeter, with a few in the center area, should suffice. Don’t glue this last connection in case the top should ever need to be removed from the base, which it likely will. This arrangement should be plenty strong.

   Another option is to add blocks under the three [?] or four [?] pedestal legs. Scrape and clean up the underside of the existing legs, and then glue and screw or clamp the blocks in place. You can match the blocks to the table’s color with stains and a few clear coats of finish, perhaps using some glaze to imitate age. If the feet of the table are carved, you can compliment the lines by carving the edges of the blocks to match the style of carving on the feet. If you make the blocks about 1 1/2 in. thick, then you can use less layers of plywood above.

   I hope this helps. Feel free to ask more if you’re still a bit unsure!

   —Andy

1. 
   hgajr | May 17, 2007 04:15am | #2

   Andy,Thanks for your suggestions. I will probably do exactly what you suggested with the layers of plywood. I will also check with the stone people to determine the size of the plywood glued to the quartz top. By the way, the top is not solid quartz; it is man-made using quartz for the design. Have a Blessed Day.hgajr