2x12 load bearing Q’s 4 countertop | GTAMotorcycle.com

2x12 load bearing Q’s 4 countertop

OmegaBravo7

OmegaBravo7

Well-known member
Wondering if anyone has an engineering background, or can speak just from experience...

The objective is to build a 9ft x 11inch bar countertop fixed at both ends (no legs or support anywhere between between the two ends).


Using two 2x12’s stacked (to gain super strength to prevent flex), 9ft long and 11in deep.

The countertop will be quartz with 4” edge

Will this bar countertop hold steady without any bend/flex? I don’t want to endanger anyone nor do I want to crack the stone.
 
Curious to why it has to stretch the 9'?
I'm by no means an expert, or even that knowledgeable, but I don't think they will stay true over time.

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have you considered a material that is more dimensionally stable ?
2 x 12's across that span should have plenty of strength
but unsupported, wood is prone to twisting etc from temp/humidity changes
not likely to be a safety issue, but not a great base for a stone counter

steel would be a more suitable material
and would not need to be 12 inches high
 
J_F said:
have you considered a material that is more dimensionally stable ?
2 x 12's across that span should have plenty of strength
but unsupported, wood is prone to twisting etc from temp/humidity changes
not likely to be a safety issue, but not a great base for a stone counter

steel would be a more suitable material
and would not need to be 12 inches high
Click to expand...
I don't think the 2x12's are gonna be vertical like joists.
I think he/she wants to lay them flat.

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J_F said:
have you considered a material that is more dimensionally stable ?
2 x 12's across that span should have plenty of strength
but unsupported, wood is prone to twisting etc from temp/humidity changes
not likely to be a safety issue, but not a great base for a stone counter

steel would be a more suitable material
and would not need to be 12 inches high
Click to expand...

I considered welded 2x3 with 1.5” legs at the ends. I figured using the 2 x 12’s would be something I can do and would be much more cost-effective

what did you mean it would Not need to be 12” high?
 
Joe Bass said:
Curious to why it has to stretch the 9'?
I'm by no means an expert, or even that knowledgeable, but I don't think they will stay true over time.

Sent from my Pixel 3a using Tapatalk
Click to expand...

It’s from wall to a small wall, that space is 9ft (it goes in front of a window which is 9ft wide).

i should’ve mentioned, this is for a restaurant
 
I would work with it as though it were a floor surface. It might make it easier to find specs.
People are going to at least lean on it, and at some point a drunk or several,
may decide that sitting or standing on it, is appropriate for the occasion.
 
2 2x12's laid flat will not have super strength as you typed, but glued and screwed together it fits the deflextion risk as per bakaboys "sagulator"

i'd look at building a torsion box from plywood using a grid system similar to an airplane wing, lots of glue and fasteners, certainly will not twist or move like 2x12's will

if it was my top I would use a steel frame or a box construction , I would not use 2x12's even though it would most likely work, but I see future problems. Gravity over time would be my concern
 
So the question boils down to is a 3" deep by 11.25" wide wood beam supported at both ends 9' apart stiff enough to avoid cracked quartz? I'm going to say no on gut feeling and run some numbers later to check.

Edit:
Based on the sagulator, you have a small chance on installing it without cracking. As soon as someone leans on it or heaven forbid climbs on, it's all over. A 100lb load in the center is ~0.8" deflection and boom goes the quartz.
 
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IIRC the deflection for stone is 1/360 of the span. Regardless of the calculations the bigger problem with wood is the reaction to humidity and warping. Things like floors get stability from cross bracing etc that might not work for your application. If it absolutely had to be wood a pri-laminated beam would be my choice. The manufacturers would have specs.

What could happen? Well if alcohol is involved, just about anything.
 
Like the man says, you can't lay boards flat, boards won't have any strength or rigidity that way. Aluminum or steel would be a better material to work with so you can keep the support beam dimensions small. Artificial Quartz is a very heavy countertop material and you have to expect patrons might lean, stand or sit on this thing at some time, it's going to need to be very sturdy.

lol I actually have a length of steel laying out back that might do it.
 
GreyGhost said:
So the question boils down to is a 3" deep by 11.25" wide wood beam supported at both ends 9' apart stiff enough to avoid cracked quartz? I'm going to say no on gut feeling and run some numbers later to check.

Edit:
Based on the sagulator, you have a small chance on installing it without cracking. As soon as someone leans on it or heaven forbid climbs on, it's all over. A 100lb load in the center is ~0.8" deflection and boom goes the quartz.
Click to expand...
A piece of a 2X4 on edge is eight times as stiff as one on the flat. The calculation has a cubed factor. The 2X12 would be a bigger waste of lumber.
 
Should I go measure that piece of steel yet?
 
Damn dudes, you guys brought up some excellent valid points

Guess I’ll have to shell out the extra cash for a welded custom steel base.

How is:
a rectangular box constructed of
Three 9ft 2x2 steel square tubes, 1/4” walls. 1/2” plywood laid and screwed on top (stone directly on steel would crack)

The legs will be 1.5x1.5 steel square rubes with 3/16” walls on each end.
 

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22 foot length of steel, rectangular profile 4" by 6" looks like 1/8" to me, used it as a concrete form it was expensive.
like 6 or 8 hundred dollars expensive. (correction 587$- lol my lovely wife found the receipt)

You could wood core fill it for extra strength, I've done that with aluminum profile tube.
 
Trials said:
22 foot length of steel, rectangular profile 4" by 6" looks like 1/8" to me, used it as a concrete form it was expensive.
like 6 or 8 hundred dollars expensive. (correction 587$- lol my lovely wife found the receipt)

You could wood core fill it for extra strength, I've done that with aluminum profile tube.
Click to expand...

That’s heavy duty right there but I don’t want to go that high on the edge. 4” or 6” height would be too high for this place.
Curious, why didn’t you use wood for framing concrete?
 
OmegaBravo7 said:
That’s heavy duty right there but I don’t want to go that high on the edge. 4” or 6” height would be too high for this place.
Curious, why didn’t you use wood for framing concrete?
Click to expand...
it was a freestanding piece that held back the 7 inch concrete pour between the main house and the garage. It always comes to a point where steel or aluminum are your only options. Men were walking on that beam during the pour, it had to be small in profile to finish the concrete and strong as **** to hold back the concrete pressure without distortion.
 
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