Hello everyone! I am very new to woodworking and got the bug bad. I just purchased a 1.5" birch top to make a smallish first bench. I've been trying to come up with a plan to make this, but they are all overly complicated without the benchtop being about twice as thick. The top is longer and wider than I need, so I was considering cutting it down to the dimensions I need, gluing the excess to the bottom and then filling in the areas where I don't have enough excess with 1.5" x 1.5" to 2" maple or ash ribs or runners spaced a couple inches apart. The plan is to glue, clamp, and screw all of this in place, and then remove the screws after the glue sets so I don't have any stray metal in the ribs so I can drill dog holes through them if necessary. Once I have this done I'll run something like a 3" piece 6/4 Maple apron around the front vise and end vise sides, which will now be fully supported by the "3 inch" thick top. I have attached a drawing if I'm not making any sense. When doubling up a laminated top to increase thickness can it all be glued together, or do I need to allow for expansion/contraction?
Thanks to anyone who can give me some advice!
-Patrick