Designing Kitchens and Bathrooms - Granite Counter Support without Base Cabinet

Hello: I plan to install two 3/4" granite countertops:
-- 41"x28" solid slab with 1/2" plywood underlay and
-- 47"x28" with sink/faucet cutouts, NO underlay

Neither will have base cabinets. Rather I want to install them each on four 2" adjustble tube table legs (stainless steel).

Can the four table legs support the granite alone (specs state a 220 lbs static vertical load)?

Or do I need to add another type of support, particularly for the one without the 1/2" plywood underlay? If so what do you recommend?

I bought the granite retail and haven't found a fabricator yet who can say for certain either way.

Cheers,
Jasper

What is the application? bath, bar, kitchen..
What type of sink? surface mount lightweight single bowl stainless, or heavy cast porcelain coated triple bowl under mount, or some where in between?
What is the deflection rate of the floor that the tube legs will be on?
Without further details I would think the one without the sink will be fine. I would think the one with the sink just needs some some horizontal cross support. Get some one to build a stainless 1"x2" frame attached to your 2" legs.

Just curious, what are you doing with all the plumbing under the sink as far as appearance sake ?

Can the four table legs support the granite alone (specs state a 220 lbs static vertical load)?


Hi Jasper,

I think that important question is how the granite load is transmited to the legs. A granite slab works in the same way as a concrete slab, so you'll need a thick slab or "beams" in order to transfer the load (granite, sink, random load, etc) to the legs without deformation of the slab
In my opinion a 3/4" granite slab is not thick enough and you will get stress / deformation of the slab. Remember that the granite is not a flexible material--> rigid materials don't inform in advance--> they just crack ;)

Hi Desert Eagle,

The deflection rate of the floor or the type of sink are not important in this case. The weight is less of the weight of a fridge or even a cabinet with a granite counter (both have legs). The puncture effect and / or deformation appear with loads over the codes' values
If you are interested, I can recommend several books about this subject

[QUOTE=Desert Eagle;1522624]

Hi Desert Eagle - the granite is for a small kitchen countertop with a stainless steel single basin undermount sink 21"x18"
(not sure the weight).

Glad you brought up the floor sloping, which I didn't think about but will definitely look into since the house is so old (100 years) and sounds like granite needs an absolutely level surface to prevent cracking.

Thanks for the tip on the 1"x2" frame.

The plumbing will be exposed for now.

Thanks, Jasper

Thanks PMGCA. Would you say a 1" underlay under the solid slab is enough and a frame ever 1' for the sinkcut piece would be enough?

Also, I would be interested in the book recommendations.

Cheers,
Jasper

Hi Jasper,

Just a note--> imagine this--> say a fat person seats on a not too strong chair, what is going to happen? the chair is going to break or the floor? --> your situation is more or less the same, so don't worry about the floor
There is more risk in the corners of the slab than in the floor under it

Underlay--> probably is enough but it will depend a lot of the type of granite, quality etc--> the most important thing s tha fact that the wood will help to transmit the load to the legs

Book--> try "Building Anatomy"