Will my floor support a Grizzly G1023SL?

[Bo]

I'm about to buy a Grizzly G1023SL table saw (left tilting with weight spec'd at 430 lbs on a 20.5" x 20.5" base) and am a little concerned about putting that kind of weight on my shop floor.

The shop is 12' x 20' with 1/2" plywood floor over 2x6's at 16"OC (they span the 12' width). The whole thing is supported on 10 piers around the perimeter without any additional support in the middle.

Should I be concerned?

Thanks,

-Bo

[Charlie Self]

Bo asks:

I'd be concerned without the saw. That's really over span for a 2x6, and the

1/2" ply doesn't help matters.

Can you get under the floor and add a doubled beam up the middle, support on the ends and in the middle?

Charlie Self "Bore, n.: A person who talks when you wish him to listen." Ambrose Bierce, The Devil's Dictionary

[frank]

Yes. Can you get a beam under the middle? Even then the 1/2 plywood it too thin. You will need to beef it up under the saw.

[frank]

If not he can work through holes in the floor, even pouring pads and slide some support under as well. Driving long pieces of 3/4 inch rebar down the side of each 2x6 as far into the ground as you can and then pouring concrete down to hold them will work as well. If not I would screw and glue 3/4 inch sheets of plywood over the existing floor.

[Bo Hick]

in article [e-mail], [e-mail] at [e-mail] wrote on 8/20/04 10:47 AM:

That's what I suspected. The room was built as a storage area originally. I do have good access underneath though it's on a pretty steep slope (about

3' above grade on one side and about 12' above on the other [then drops another 15' into a creek that our house spans]).

So if I were to run a double beam of say two 2x10s (or?) down the center of the 20' length (making the 2x6s span only 6') and support it with another

4-5 piers and then use additional ply (maybe 1/2"-3/4") under the saw itself..does that seem like I might be in better shape?

I don't want to win a Darwin award and drop my new saw through the floor into the creek!

Thanks for all the help!

[Charlie Self]

Bo Hick asks:

What I'd do is run tripled 2x10s, three piers, though four lets you place all breaks on a pier. Then come back with 3/4" T&G flooring. Screw that down. You might want to use adhesive, too.

Then, when you go nuts and decide you gotta have an 800 or 900 pound 20" planer, you're safe.

Charlie Self "Bore, n.: A person who talks when you wish him to listen." Ambrose Bierce, The Devil's Dictionary

[frank]

IMO 3ply 2x8s would be a better choice.

3/4 inch screwed down would be about right. I have a friend who used 2 glued sheets of 3/4 K3 particle board to firm up under his jointer. K3 is cheap, just don't get it wet.

[Bill Stock]

Seems a little light. My shops on a concrete pad, but we do have an aquarium in a similar sized room with 2*8 joists. The aquarium probably weighs about

800 pounds, but it's on the outside wall perpendicular to the joists. It's been there a year, but YMMV.

Get two large friends to stand beside you in the spot where you want the saw and see how much give the floor has.

I guess you don't want to spread out the weight of the saw by building a longer base (90 to joists) for it? This would play havoc with the height and make it a bitch to move.

[Gary]

No shortage of opinions here, and here's mine. What you have is a real nice trampoline; boing! boing! boing! Sounds like you had Darwin for an architect; 2X6 joists with 12 foot span overhanging a river.

I agree with a couple of the others, put a beam of 3 ply's of 2X8's down the middle and sheath the entire floor with 3/4 ply with glue and screws (T&G would be too costly and less structurally sound, i.e. a joint ever 2.5 to 6 inches.) 1/2" ply is not fit to walk on, much less place a heavy machine on.

Gary

[David]

That, or use 1-1/8" Sturdifloor, a T&G flooring product that's even avail. at HD. For that small of an area, the cost bump is insignificant.

David

Charlie Self wrote:

[Gary]

about half way down that beam to support it.

================================== | | | |

[Charlie Self]

Gary responds:

T&G plywood isn't much more costly than straight sanded. It forms a better floor than butt jointed.

Charlie Self "Bore, n.: A person who talks when you wish him to listen." Ambrose Bierce, The Devil's Dictionary

[Gary]

Yeah, that's the stuff I mean, 3/4" T&G plywood. In fact, I think its called Sturdi-floor. You said "Then come back with 3/4" T&G flooring" which I read to be solid wood "flooring". Looks like we're in sync now.

[Dave jackson]

You are already over the limits for a 16" o.c. 2x6 span by almost 2 ft.for a max 30 lbf/ft live load (the minimum allowed) floor. Definately add a sturdy girder of at least double 2x10's under the exsisting and support it in at least three places. Nail the girder together with 3 16d nails vertically every 16" or so on both sides. Get 3/4 ply or osb and glue and nail it to the 2x6 joists over the 1/2". Use 5-6 8d ring shank nails per 4' row. This should solve the trampoline effect on your floor. --dave

[Bill Rogers]

If you are of a mind to have only 1/2" plywood for a floor over 16" spans, you should be concerned about doing any woodworking at all. No matter if you inherited it or built it, rebuild it ...properly ...even if you don't have a ton and a half of shop tools.

Bill.

[patriarch]

David wrote in news: [e-mail]:

I've used this stuff recently, but it's also been around for maybe thirty years in a similar form. We put it down with Liquid Nails and pneumatic- driven 16's. The floor no longer bounces. At all.

Less than $50/sheet at Orange BORG. Take someone along to help you load it. Not a one person job for anyone I know.

Patriarch

[Bo Hick]

Actually my grandfather (a firm believer in Darwin) built in the early 70s. I think he was flying the communist flag in front of the house at the time and probably smoking a lot of what he was growing. It is Northern California after all! I think the only reason it's still holding together pretty well is because my grandmother oversaw it all.

-Bo

[Bo Hick]

in article [e-mail], [e-mail] at [e-mail] wrote on 8/20/04 11:37 AM:

Thanks to everyone for all the advice...what a great resource! I went down today and drilled a small hole through the floor and found that it is actually 3/4" ply (not 1/2"). Not that that really changes a whole lot in the long run.

I think my plan is going to be: Triple up 2x8s (I have many long ones around) run them down the middle and support them with piers in four locations. Then screw & glue some sort of sheet good (maybe Sturdi-floor or OSB [I'm not familiar with K3]) overlay to the whole floor.

As it stands I'm surprised by how little trampoline effect I get right now. If I stand in the center of the floor and hop up and down (I'm 180 lbs) I don't notice any real deflection in the floor. At any rate, I'm going to beef if up and get that saw in there!

Thanks again,

-Bo

[Eric Tonks]

You may also want to diagonally brace those piers. I would not want to put much weight, vibration and movement if the tall ones are not braced. The whole shed could fall into the ravine.

[Mike Marlow]

I'd be more concerned with 2x6's spanning 12 feet than I would with 1/2" ply spanning 16". I agree that 1/2in does not make a good floor, but 12' is too long for 2x6 floor joists.