How to support 90" countertop in sewing room?
November 10, 2013 6:52 PM   Subscribe

How can/should I best support a 90" span of countertop, in a room where we want to do sewing, crafts, and schoolwork?

This room has a 90"-long wall where we plan to hang up a countertop. We don't want to have to put in a center leg; must we? Or can we get by with a couple of strong L-brackets at the back of the countertop that tie into the wall studs? (I already plan to run lengths of 2"x4" around all three walls to help hold up whatever countertop we choose.) What's the maximum span I should be working around?

My first idea was to use a slab of laminate countertop, or maybe a pair of 2"x12" or 2"x10" boards joined together. (But I also saw where someone used cheap laminate flooring on plywood so they could easily replace damaged segments. Clever!) Is laminate-on-OSB the best choice for the worktop? My wife is worried that it will chip easily. Would a couple of wide boards, glued up into one plank, be better? Or something I am not thinking of?

We expect this to bear a fair bit of weight, from a sewing machine up to a couple of kids working together on a project and leaning their full weight on the countertop to cut things.

Thanks for any advice or experience!
posted by wenestvedt to Home & Garden (12 answers total) 4 users marked this as a favorite
I'd put in a center support just because when my sewing machine is at full speed, having the table surface vibrate is incredibly irritating. Perhaps instead of a leg, you could build some kind of storage cabinet or drawers.
posted by jamaro at 7:10 PM on November 10, 2013 [5 favorites]

If you want maximum stiffness (and you do) you want to use plywood, not OSB. OSB is great where sheer strength is needed but it flexes as LOT. I would use two thickness of 3/4" plywood fastened together with screws and construction adhesive with laminate glued on top. You can get individual squares of laminate that come with the glue already on them and it will be very easy to replace when you chip a square (make sure you buy lots of spares as the manufacturers switch out colors and patterns often and finding one to match in the future could be tough). An L bracket probably will allow some flex in the top mid-span as they don't usually have enough support without a hypotenuse connection. What I have done in my workroom is to install a triangle support underneath so that the hypotenuse is from the front of the workbench to the baseboard behind the counter-top. I used the double thickness of plywood as mentioned above and just cut it with my circular saw in the shape I needed to fit exactly. This allows for a lot of support but still keeps the area underneath clear for legs and such. If you want a really cool looking countertop you can install engineered wood (or even pre-finished hardwood for a butcherblock look) flooring on the workbench.
posted by bartonlong at 7:15 PM on November 10, 2013 [1 favorite]

I have a basement area with several laminate countertops (formica over particle board). typical home depot kind of stuff. Supported at about 3' intervals by a frame the prior owners installed. It has been sitting there for more than a decade and is warped 10%. The frame is lame, small dimension lumber, made into X braces. Not very professional, but even if it were, the spans invite warp, even under no load.

if you want it to be 'furniture' quality, i'd aim for dense supports....24" or less. You can make big wooden gusseted L brackets that extend from the wall forward, but don't expect the material to be perfectly flat in a few years. Kitchen cabinets continuously support front, rear and sides and that's one reason they look OK for a bit. If you can find TWO used cabinets and place one at either end, you can have a big empty space in the middle that can be easily bridged with good supports over a smaller span. Might work better. Plus, storage.
posted by FauxScot at 7:22 PM on November 10, 2013 [2 favorites]

If it were me, I'd want to maximize possible storage space. Could you put cabinets or shelving under parts of the counter, both to make best use of the space and to help support the counter? They wouldn't necessarily have to be as deep as the counter, they could be set back to allow for some knee room if someone was sitting there. And you could have some deeper storage in some areas, which could be the places you use for standing work.

I am envious of you being able to have such a long workspace, but I'd be even more envious if you had a ton of room to store fabrics, papers, and whatever other supplies. Can I come play?
posted by padraigin at 7:50 PM on November 10, 2013

If you do decide to go the drawer route, these Ikea Alex drawers are awesome, and can be very stylish.
posted by barnone at 8:10 PM on November 10, 2013

Best answer: If you take a 2x4, stand it on edge supported at each end, and then stand in the middle you'll barely flex it. Three 2x4s on edge and then screwed to a piece of 3/4" plywood are easily going to support the loads you are anticipating.

So that's what I'd do. Make a frame for your shelf out of 2x4s. Have three lengths of 90" (each edge and one for the middle) and then two short lengths at each each to fit between the lengthwise pieces. (this keeps the lengthwise pieces fully supported by the blocking you are setting the shelf on). Glue (regular carpenters glue) and screw (don't use nails, cheap deck screws or gyproc screws will work) a sheet of 3/4" plywood to the top of the framing and then glue down a sheet of counter top laminate using contact cement.

Some ways to fancy it up:

Cut a 3/4 x 3/4 rabbet (actually most 3/4" plywood nowadays is 11/32" so watch for that and make your rabbet match the thickness of your plywood) in the back edge of the front stringer. Ripe 3/4" off your remaining two stringers and your end cross bracing. Then when you add your plywood to the framing reduce it's width by 3/4" but run your laminate right to the edge. This gets you solid wood over the entire front edge of the shelf instead of an unfinished plywood edge.

If you have access to a router then once the laminate is glued to the substrate you can take a round over or 45 chamfer or ogee or finger nail bit and cut a detail on the top edge. This eases what is otherwise a painfully sharp edge. This is also the easiest way to perfectly match the edge of the laminate to the shelf.

If you don't have a router at least take a hard sanding block and round over about an 1/8" of the top edge.
posted by Mitheral at 9:01 PM on November 10, 2013 [1 favorite]

Response by poster: Thanks for the answers so far! Keep 'em, coming, please.

Ninety inches may sound like a lot, but I am six feet tall so my arms come surprisingly close to both walls (72") when I am in the middle of the room. :7)

We are hoping it can be used solo or by two people, so I am going to think seriously about Mitheral's plan as a way to avoid a center leg.

And jamaro, you are entirely correct about the dancing sewing machine!
posted by wenestvedt at 4:11 AM on November 11, 2013

Best answer: I found this when I was looking to make a long desk (6 feet long). This guy made a really long desk for his wife to use a sewing desk.
posted by Jaelma24 at 4:54 AM on November 11, 2013 [1 favorite]

I've got a wall-to-wall desk that's about 10' long, supported on cleats along the back and sides. It's made out of 2" thick ipe. It was pretty solid and stable that way, but when we put a single supporting leg at the front center, it became noticeably more stable.
posted by adamrice at 8:12 AM on November 11, 2013

Response by poster: Dang, that's a slab of a desk!
posted by wenestvedt at 8:26 AM on November 11, 2013

Jaelma24's picture is exactly what I was trying to describe. Mine are solid, not a frame but the end effect is the same.
posted by bartonlong at 11:36 AM on November 11, 2013

Response by poster: I want to build those sweet-looking cantilevers, but I didn't have time. :7(

So in the end I bought a 8-foot piece of the cheapest formica countertop at Lowe's and cut off like four inches (with a new, super-finetooth blade for my circular saw) from one end. I hung 2"x4"s on the side walls as cleats, and then bought two angled steel brackets at Lowe's that were rated for 400 lbs. each and screwed those into the studs under the counter.

Nothing in the damn house is square or level, so after I dropped the counter into place I drilled one nice, long screw down through the countertop into each of the 2"x"4s and made it pretty with a finish washer. Steady as a rock now!

The counter cost I think $83, the brackets were under $10 each, and the lumber & screws I already had. DONE!
posted by wenestvedt at 8:51 AM on December 5, 2013

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