Floor load calcs need help

[YLee Kioti]

Received a Graceland Portable building, a 12 x 20 with 12" center floor joist.
Graceland could not tell me size of floor joist, neither seemed interested in finding out. It appears that sales is the strong point and tech support is a bother(?), my perception only folks. Not a slam on them, it's how I perceived the conversation.

Was informed that floor loading is 60# live load (moving something around)
and 10# dead load (storage) per sq. ft.
So based on the info below what or how would one calculate how much # per sq. ft. is this mower placing on the floor?
Just a quick take I did a 6'x4'/800# and got 33.3.
However, I'm thinking this is too simplistic?
If the mower does overload the floor (floor material is the synthetic not plywood), would adding a layer of plywood help with the load bearing?

My Gravely weighs in at 802#.
Here are specs on the ZTHD 48:

Weight (assembled) 802# Length 79 in / 200.7 cm Width (Chute Up) 50.8 in / 129 cm Wheels Front 13.0 x 6.5 in - 6.0 in (33.0 x 16.5 cm - 33.0 cm) Wheels Rear22.0 x 11.0 in - 10.0 in (55.9 x 27.9 cm - 25.4 cm)

 

[bigtiller]

Are you sure about the 60-10 live/dead per sf load weights?

 

[Runner]

The dead load (10) is the weight of the structure (joists and floor surface). The live load (60) is how much load you can put on it per square foot. So you are OK from an overall loading standpoint.

You might want to check your floor sheathing material to make sure it is able to resist the 200lb point loads from the four wheels.

My guess would be it's OK. The Engineers will be along to check me shortly....

 

[YLee Kioti]

Are you sure about the 60-10 live/dead per sf load weights?

Yes, got them from Graceland support via two phone calls.

 

[YLee Kioti]

The dead load (10) is the weight of the structure (joists and floor surface). The live load (60) is how much load you can put on it per square foot. So you are OK from an overall loading standpoint.

You might want to check your floor sheathing material to make sure it is able to resist the 200lb point loads from the four wheels.

My guess would be it's OK. The Engineers will be along to check me shortly....

So the sheathing is that synthetic flooring material. Not sure how thick it is. The support guy did not convey interest in answering my questions.
Now am considering laying in some 19/32 plywood. Three sheets, for driving in and storing the ZT.
Then I'll have a trip point mid-floor of shed-sigh...or spend more cash and lay in entire new material over the synthetic floor.
Hm..

​

 

[paulsharvey]

So, if we figure each rear tire is supporting about 200#/sf, we probably are at the point that If you park the ZTR in the Same place, every time, or leave it parked for months, you will likely get some subfloor sagging. I dont think you should worry about falling through or anything.

You can solve this by screwing down 2x12s in the wheel path. They won't really do much add strength, as much as spread the load over a greater area. If you chamfer the ends, you won't be bothered hopping up onto the 2x12. We won't change the live loaf at all, but we can half the #/sf that you are creating (or maybe 1/4 the live load).

 

[paulsharvey]

You can't think of the ZTR as a 4x6 area; the weight is applied to the floor in 2 smallish areas (rear tires) and 2 small areas (front casters).

Adding plywood won't Hurt, but it will deflect with the floor, something more rigid, like 2x material will spread the load across the floor joists/subfloor, and you will be fine.

 

[YLee Kioti]

I agree: something more rigid, like 2x material will spread the load across the floor joists/subfloor, and you will be fine.

It's my tunnel vision that gets locked up. So yeah this is good.
I happen to have two 2x 12's.
So, soon as I'm done stapling insulation and tinting windows, it'll be move in ready.

Appreciate the: simple is good approach. and the shed 12' width gives me room to park it over the 2X's.....!

Alrighty another quality job well done!

Thanks everyone.
Hey and appreciate y'all not snitching to my wife.
She tells me all the time: you over thinking it again!

 

[ning]

Do you know which directions the floor joists run?

 

[paulsharvey]

Do you know which directions the floor joists run?

In almost all of these buildings, they will be running across the short span, which works perfect, because generally, the door is going to be on the narrow side, and running 2x12s in the wheel path, you can span something 8 floor joists.