# Weight limit of plywood floor?



## UKCat

The floor in my shop is 3/4" plywood on treated 4×4 with 24" centers. I am trying to find out how much weight it can safely hold. I am hopefully going to pick up a G0490X tomorrow and this thing weighs 500lbs. I am concerned about putting it in my shop without doing something to strengthen the floor. I have a 250lb table saw and 300lb planer in my shop and the floor seems to support them without any problem, so maybe I'm worrying over nothing. Anyone have any advice on this?


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## sawdustbreath

It depends on how big the span of the room is to determine joist size and length


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## Finisher

You don't mention what your 4×4's are resting on? But, 24" center to center joist spacing is acceptable in construction that uses floor trusses and that type of floor I think is rated at 400 lbs. per square foot. The problem does exist of floors bowing a bit when you walk over them so I would think this would be a concern but if you are not experiencing that now you shouldn't be concerned.


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## UKCat

The 4×4 are on 2"x4"x6"(?) concrete slabs every 2 foot.


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## dkirtley

Low tech diagnosis: Jump up and down on the floor where you want it. If it is bouncy, you may have a problem.

Simple solution if it is too bouncy is distribute the weight with something under it and make sure you place it on a support beam.

Bouncing will be the biggest problem. I can't see a 500 lb static load being a risk of crashing through the floor.


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## bondogaposis

What is the span of the floor joists?


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## Granddaddy1

If I understand correctly, you basically have a sheet of 3/4" plywood installed on 4×4 joists placed 24" on center. Then the 4×4 joists are bearing on concrete footers or blocks placed 24" on center. If that is the correct assembly, and your concrete footers are level and adequately placed, your floor system will hold much more than what you're considering.

Good luck!


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## a1Jim

As a 25 year contractor I agree that you have more that enough support for a 500+ weight machine ,The other thing I would precaution others about is that 4×4s are not meant to be horizontle weight bearing members their only meant to bear weight for vertical loads . What should have been used is 2×6s pts or larger depending on spans.


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