Designing Kitchens and Bathrooms - Granite countertops on particle board?

My cabinets are made of oak veneer plywood on the front, back, and exposed sides, but the inside dividing pieces and floors are particle board, will this support new granite counters?

Please let me know, I had posed a different question on here and someone named "Mantripp" made a comment about a neighbor having their particle board cabinets collapse from the weight of the granite, (though I'm not sure if their cabinets were ALL particle board or just partially (like mine). Now I'm concerned, anyone with experience or insight on this?? Please share your thoughts! Thanks!!!

Sharon - My cabinets are maple face frame with particle board boxes. I have granite countertops. The installer assured me that it would be no problem. I did have to install additional support over the sink and dishwasher (no cabinet) opening because of the large cutout in the granite.

Sharon ES,

As Wayne mentioned, there should be no problem at all. When someone says they collapsed, I think other issues were involved and not mentioned. It's amazing how fear strikes those wanting to do the right thing.

Although not necessary, DEPENDING ON WHERE THE COUNTERTOP IS LOCATED, it is recommended that you apply ¾ inch plywood sub-counter to the top of your cabinets to support the granite.

This does a couple of things...it will add support above appliances such as dishwashers and compactors, support holes for sinks and cooktops. It also helps support small cantilevered ends and breakfast bars. The slabs can be glued to this plywood surface using thinset, liquid nails subfloor adhesive or a two part (bondo) type adhesive.

The advantage to plywood is that you can level the slabs much more easily without moving them once they are in place. In any event, if you are using frameless (european type ) cabinets or framed cabinets that have upper retractable cutting boards, you will need to raise the granite ¾ inch to clear the double bull-nose which hangs down ¾ inch. Plywood is a cheap and easy way to do that.

Hope this helps!

Hi, I have a similar situation. I am in the process of putting new cabinets in my kitchen. They have maple wood doors but the cabinet frames are made of particle board. They are new and feel very strong so I am not concerned about the weight of the granite, but I do have some related questions. I will be hanging the upper cabinets soon but the granite isn't in place yet. What is the thickness that I could expect for the granite, so I can account for this when I hang the upper cabinets? Should I go ahead and put the 3/4" layer of plywood down, as recommended here? And the granite will be another 3/4" (2cm) or 1-1/4" (3cm) depending on the thickness of the granite, is this correct? So, from my un-finished cabinets, I could expect another 1-1/2" to 2" right? What about the span accross the dishwasher, I'm assuming I will need to span some 2x4's across? Thanks for any advice!

floridagator,

MINIMUM distance between TOP OF COUNTER TOP and BOTTOM OF WALL CABINETS is 18". If using traditional counter tops, they are normally 1 1/2" - the total space requirement is 19 1/2".

So when marking your wall cabinet placement, the total distance from floor to bottom of your wall cabinets should be 52 inches. Regardless of the cabinet height, 30, 36 or 42, the minimum distance of 18" should be maintained between top of the counter and bottom of wall cabinet.

If you are going with granite, regardless of its thickness, this is of no matter UNLESS you are installing appliance garages. Then it is a matter of either calculating the actual garage height, 3/4" plywood, granite top. Personally, there is trim available to finish this type of install so the 19 1/2 inch rule is considered standard.

You must have a minimum of 17¹⁄₂" between counter top
and the wall cabinet for proper appliance garage operation, if you are installing any.

2x4's are not needed and frankly don't know where that came from! Particle board cabinet boxes are strong enough to handle granite so they is no need for any concern here.

The gap between cabinets where the dishwasher resides need only to have 3/4" plywood. Thus the need for 3/4" plywood placed over all the counter tops is best as I described in the earlier posting. The total height from floor to top of 3/4 plywood is 35 1/4 inches.

Hope this helps!

To my knowledge, only the 2cm slabs need the plywood underlayment, the 3cm do not and in fact I have never seen ply under a 1& 1/4" slab. If you were setting granite 12" tiles you would need two layers of 3/4" ply and the 2x4 cleats as extra supports wherever you could fit them in, especially in the corners and in the sink areas where long open spans are prevelant.

Tileguybob,

In most older homes whereby the existing cabinets are not level, I suggest using plywood. As I mentioned before in my previous posting, not always necessary but it has its advantages WHEN it is used.

In new homes, where installations of cabinets were right on the money, I have not seen them use 3/4" ply unless we had longer spans that required additional support, regardless of the thickness.

Just want to make sure everyone understands the reasons behind it, not reasons not to use it.