Kitchen Cabinet Design Question

[Jeff Wright]

I will be building my kitchen upper cabs using face frames attached to the carcass sides using the Sommerfeld offset tongue and groove system. The backs will be glued and installed in grooves set back 1/4 inch from the back edge of the carcass sides. I will build rail and stile frames to insure the top of the carcass components are held square. The back will be screwed into that top frame. The carcass sides will be 3/4 B-1 prefinished ply. The face frames will be 7/8 inch thick poplar (painted).

Question: Will 1/2 inch ply be sturdy enough for the backs versus 3/4 inch IF I plan to screw the cabinets to the wall through the backs and NOT use an upper or lower mounting strip? I would prefer using the 1/2 inch to save weight (and to some degree, cost); plus it would afford slightly more interior room.

[Roger Jensen]

I researched this a while ago and everyone thought 1/2 inch backs would be strong enough without additional mounting strips. I'm also using Spax screws from McFeely's to attach the back (they also hold the boxes together while gluing).

Roger

[Steve Clardy]

1/2 will be fine.

[Greg Riach]

Jeff

I have built a number of kitchen cabinets very similar to yours. I used 1/2 inch ply for the backs, and fastened as you are planning. I have had no problems after 10 years use.

Greg

[Peter Quinn]

I can't say I like the idea of large upper units bearing significant load held up with 1/2" backs and no screw cleats. It is not an issue of the cabinets strength, most are built to the point of over kill and I'm sure yours will be very strong. I worry about the screws pulling through the 1/2" material. I suppose using a #10 screw with a washer head like fast cap hanging screws would solve that worry, so I'd probably be careful to choose the right screws. For lowers I see no issues either way.

[Gene Howe]

Why not go all the way with marc's system and put the 3/4"X4" piece across the back, tongued into the top and bottom sides of the cabinets? I did that and grooved the underside of the 3/4"X4" and top side of the bottom piece. That made my back panel 1/4" thick. 1/4" walnut is a lot cheaper than 1/2". Of course, I downsized the cross pieces for the shorter cabinets.

[Jeff Wright]

Why not go all the way with marc's system and put the 3/4"X4" piece across the back, tongued into the top and bottom sides of the cabinets? I did that and grooved the underside of the 3/4"X4" and top side of the bottom piece. That made my back panel 1/4" thick. 1/4" walnut is a lot cheaper than 1/2". Of course, I downsized the cross pieces for the shorter cabinets.

Thanks Gene. I have made some cabs as you describe with Sommerfeld's system, however I found those top and bottom nailing boards ended up positioned flat against the wall and would prevent my scribing the cab sides to an uneven wall.