Base cabinets and low wall to support granite countertops

[Arman]

HI,

We are getting a 1 1/4" granite countertop installed, and I have a feeling we are going to have to reinforce our base cabinets. The construction is thus: 1/2" particle board sides and back and 3/4" solid Oak face- probably the cheapest possible builder supplied cabinets? The oak face looks like it has only been tacked to the rest of the cabinets with brads. I dont think they have been attached to each other real tight, I couldnt see the screws, unless they are hidden or something. Will such cabinets support the granite? What do I need to fo to reinforce them? I have a 8' straight run, a 2'-4"x

3'-10" "L" and a 6' long island.

My next question is, we plan to raise the bar area a few inches off the island surface and were planing to support the granite with a 2x4 wall. Do I need to pin this wall to the cabinets supporting the island? Also, when I attach the wall to the floor boards, do I use nails or screws, and how many at each point? This wall is also L shaped, will it be self supporting? What Can I do to prevent it from toppling over, like someone had asked earlier? THe granite over hang will be supported by brackets.

We are already way over budget with the granite and would like to reinforce the cabinets and build the support wall ourselves. I had taken a carpentry class with the carpenters union in Pittsburgh, so I am fairly confident I can do this.

Any help would greatly be appreciated.

Thanks and have a great weekend.

-Arati.

[Mike G]

Granite weighs 168 # a cubic foot. I'm not about to do the math but I would guess that some bracing or internal framing would be required

[Ralphw]

hello, Unless the cabinets are really in rough shape they should be fine, we just did a reface with old 5/8 melemine cabinets sides set 1 1/4 stone on top and all is fine.

screw the wall into the floor ...in floor joists if possible....and yes attach wall to cabinets...if the island is attached to the floor then you should be fine. Ralphw

[Bridger]

I'd worry about that.

standard operating procedure for one local kitchen remodel shop here is to support the stone on a tubular steel frame, bypassing the cabinets completely.

first thing I'd do is get the opinion of somebody local. we can't see what you have or shake it up a bit to see if any parts are ready to fall off or what.

pinning the wall and the cabinets should help them both. a good connection there will also help the joint in the stone to remain tight.

don't put so many fasteners that you split the wood. frame walls by themselves are great for compressive loads (straight down), but not as good for racking (shifting in the plane of the wall) or uplift. racking strength gets better with sheathing (see below) and uplift can be dealt with through the use of hardware.

being L shaped definitely helps. being U shaped would help more. what will support the free corner? sheathing it with plywood also helps.

3/8 CDX on one side should be fine. if you're still worried, glue the ply to the framing.

if you're worried about the wall overturning fasten it to the floor either with allthread or straps. you didn't say what your floor was made of, but the strap will need a solid connection (not nails) to the floor. if it's joists and sheathing, get a lag screw into the joist, through the strap, which wraps up over the top of the wall. if it's concrete, get an anchor drilled well into the slab with the allthread connected to that , running to the top of the wall with a nut over an oversize washer.

if the support is well designed, overturn shouldn't be a problem.

make sure that there is support fairly well distributed beneath the stone. fastening the stone to that support is the installer's job.

'

look inside your cabinets for places where you can slip in some support that will reach from the bottom of the granite to the subfloor. try to take the weight off of the cabinet wherever possible. particle board isn't known for great longevity in damp locations like kitchen cabinets....

2x4s can support a hell of a lot of load in the lengths you're dealing with

[Swingman]

Strictly some thoughts in the FWIW category:

You have limited choices without going to more expense. Seems like the guys installing the granite could give you some input, but then again, my recent experience is that many of these 'installers' just want the money and could care less.

Are the kick plates built in, the boxes themselves mounted on a kick plate base, or do they use leveling legs? The anwer to those questions will be of paramount importance, with leveling legs being the most problematic in my experience.

A 1 1/4" slab of granite is going to weigh roughly +/- 24 lbs /sf. That is thick granite, most of what I've seen is 3/4" slab which weighs in at around

15 - 20 lbs/sf ... with bullnose trim, it looks 1/14" thick.

Can you get by with thinner granite at a reduced weight/sf?

Although it is impossible to tell without seeing the cabinets themselves in person, if the base cabinets are sturdy and will not rack when force is applied front to back or side to side, if they are screwed to the wall through solid tack plates on the back, AND to each other; AND if you have a solid plywood substrate for the top that further ties the cabinets together, then most of the weight should be distributed straight down and you will most likely be OK, even with "builder's specials" ... again it is difficult to make that call without being there.

If they were mine I would do the following as a minimum if budget was a consideration: Satisfy yourself about the sturdiness of the kick plate method and/or legs; Make sure the base cabinets are adequately fastened to studs in the wall, and to each other; Brace (with glue and screws) the tops with 3/4" X 4" plywood triangles at the top four corners of each box; Add a

3/4" plywood substrate across all the cabinets and make sure that it is screwed into each corner brace at the top of each box.

You should be able to get a gut feeling of the effectiveness of these types of measures on your cabinets ... go with the feeling.

[Arman]

Hi all, thank you so much for your suggestions.

THe cabinets are maufactured by Wellborne and here is how they are constructed:

dont have levelers, at least not that I can see them. Kickplates look like they were attached to the sides.

Once again, thanks to everyone for your input!