How do I support a granite countertop over a dishwasher?

Question

I'm currently designing a kitchen for myself - I'm going to be building all of the cabinetry, and I'd like to install a granite countertop. The counter will probably be 2cm thick as I'm told this is a standard thickness, and I'm also told that this will need plywood support, which is fine as I'm actually just going to build my cabinets with a full ply top for support, but how do I support the countertop over the dishwasher? I found some websites talking about "mesh support" but they also said that this is not sufficient for a 2cm worktop, and I also can't find out what this "mesh support" actually is.

This is the dishwasher we've bought: https://www.frigidaire.ca/Kitchen/Dishwashers/Dishwasher/FGIP2468UF/

It says that the minimum height is 33.5" and the underside of our countertop is going to be at 34.5" so do I literally just put a sheet of ply across the gap between the two cabinets (I would be able to do this in such a way that the two cabinets will effectively built together with a single board spanning the top of both cabinets plus the gap, if necessary)? Will that look strange?

Edit: I should clarify, I double checked with the supplier and they told me that standard in Canada is to have a 2cm thick or 3cm thick solid slab without a separate nosing/apron on the front. The two answers received so far are therefore not relevant to my situation.

Answer 1

The dishwasher gap needs no special support. But it usually requires a brace to attach the dishwasher's tabs to, which is then covered by a trim.

1. Install the lower cabinets, sink cabinet(s), the pantry cabinet and the fridge panel..etc. If you also install the upper cabinets, that's fine.
2. Leave the gaps for the dishwasher and stove. Install a dishwasher brace.
3. Buy the sink
4. Call the installer to measure and determine what support is needed, if any.
5. The installer will place the granite, glue/caulk it to the cabinets.
6. The DIYer can install the under-mount or drop-in sink, silicone the counter edges, tile the backsplash etc..

A countertop that is 3/4in thick (2cm) may require underlayment, usually 1/2in or 3/4in plywood, to spread out the support around the cabinet sides it rests on, but it won't add much to the strength.

Another reason to add an underlayment is to visually build it up for a thicker look with nosing, and to avoid the extra weight.

A countertop that is 1.25in thick (3cm) usually does not require further support or build-up.

The price difference is often small enough that the thicker look is simply achieved by thicker granite rather than a lamination plus nosing.

The plywood has nothing to do with spanning the dishwasher gap: usually kitchen cabinets have no top, and the only support for the countertop is provided by the sides of the cabinets. Whether there is a dishwasher or a drawer underneath makes no difference.

Also, adding plywood on top of the cabinets is not going to close the gap between the bottom of the counter-top and the top of the dishwasher. To close that gap, you'd apply a trim, and treat it very well do withstand the steam from the dishwasher.

Different manufacturers have different requirements and practices, and whether plywood is added depends on the stability of the chosen granite and how it will rest on the cabinets. The origin of the stone and thus its strength matters, but I can't imaging that the country of installation would matter.

If the plywood is applied, nosing is required to hide the lamination edge of granite & plywood.

Your granite stone finisher will apply the plywood and nosing for you for a strong hold and finished look.

Bracing for the dishwasher space may be provided to ensure proper 24in sizing of the gap for it. The brace can be removed after installation of the granite. Or you can keep the brace in order to screw the tabs at

If plywood is required, you would generally not install the plywood for them, and instead leave the cabinets and dishwasher spot open on-top. Best to confirm with the installer.

If you are applying (granite) tiles for the counter top -which is a different matter-, then the plywood would be installed first, and then the tiles are laid on top.

Image: https://www.diynetwork.com/how-to/rooms-and-spaces/kitchen/installing-a-do-it-yourself-granite-countertop

Answer 2

It shouldn't "look" like anything at all, when finished (the countertop, nosing, and installed appliance/cabinets would hide it, unless you are not nosing the granite top, which will look weird, and not just there.)

Nosing = extra material at the front edge of the countertop, hanging down. Commonly a strip doubling the thickness epoxied on with appropriate granite countertop epoxy. Then that double-thick edge is trimmed, ground and finished. Discuss with your stone fabricator, or look it up if you are your stone fabricator.

A single sheet spanning the three spaces would be best, yes.

Answer 3

Using ply between the cabinets and the worktop makes sense. Since the span for the dishwasher is around 600mm, 1/2" ply (marine for when water drips round the back, etc) will be enough - the worktop itself is totally supported by it, face to face. O.k., if you're going to sit or walk on it, go for 3/4".

It makes sense that there will be a space, as small or large as you want, between top of dishwasher and bottom of ply. If the ply rests on the dishwasher, it will be a pain to get it out when it goes wrong.