# Shed Floor - Options to make more rigid?



## joecaption (Nov 30, 2011)

It's needs that third 4 X 4 or it's going to sag and the door will stay out of wack.
A 2 X 4 joist at 24 O/C would be a disaster, add those extra joist, with the joist that close to grade I would be using PT.
If that shed's walls are not at least 6" above grade there's going to rotting issues.
What do you mean by 3/4 PT for sheathing? Do you really mean for the sub floor?
I would not use that for a sub floor or for sheathing, it's going to be soaking wet, full of voids and loves to delaminate, no T X G.
Use Advantech instead.


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## lenaitch (Feb 10, 2014)

I agree that door #2 is the best way to go. At 6' your are right at the span limit for a 2x4 no matter how many your have.

If it's not too late you might see if you can find deck blocks that are grooved for 4x lumber. Regardless, your blocking should be set on pads of several inches of limestone screenings or something similar for drainage. If you are in an area subject to freeze-thaw try to avoid using hollow concrete blocks.

I agree that a plywood floor is perhaps not ideal but I did the same several years ago in a house we used to own and it is still fine. Unless you use it in such a way that brings in a lot of moisture (like a snowblower), a shed floor stays fairly dry. It is, after all, a shed.


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## kal72 (Jul 10, 2016)

Thanks for the replies. So I will get a third 4x4... Sounds like adding the extra joists at 12" oc might not be a bad idea either or wouldnt be needed with the third 4x4 beam? After reading Joes reply, I just read about the advancetech flooring - never heard of it until now but a little too late. I thought I as doing well by listening to the Lowes guys and spending 3 times the price on PT vs OSB.

All my floor assembly is pressure treated including plywood floor -the plywood will be 6" above grade. I have the 3/4" crushed and screening under my block, but I did use cinder blocks with holes and I am in Ontario...hadn't heard how they work or not in freeze thaw.


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## Fix'n it (Mar 12, 2012)

3 4x4 skids. 1 in the middle, the others all the way out under the wall = NO overhang .
2x4 16o/c would be ok for what you are doing. 12" o/c would be better = in case you get a tractor or motorcycle or whatever. 

your plywood is fine. just glue the gaps when the shed is done.
and don't let the plywood get wet, cover it if its going to rain.


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## Fix'n it (Mar 12, 2012)

oh. i am building a 10x12 right now.


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## kal72 (Jul 10, 2016)

Thanks Fix!

What do you mean by "Glue the gaps"?

I already have it framed at 24" OC, so easier now to just add joists to make it 12" (16 is no longer an option unless I re-do). 

No overhang makes sense now that I am going to 3 skids, but too much rework at this point to do that. Best I can do is to probably have 8" of overhang at the door, and 12" at back of the shed.


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## lenaitch (Feb 10, 2014)

If you can still get at them, consider filling the block holes with screenings.


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## Fix'n it (Mar 12, 2012)

kal72 said:


> What do you mean by "Glue the gaps"?
> 
> I already have it framed at 24" OC, so easier now to just add joists to make it 12" (16 is no longer an option unless I re-do).
> 
> No overhang makes sense now that I am going to 3 skids, but too much rework at this point to do that. Best I can do is to probably have 8" of overhang at the door, and 12" at back of the shed.



you probably will not have open gaps where the ply meets up (mine does, so i am going to close them with construction adhesive.

yeah, go 12" o/c. 

lets see a pic of what you have.


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## kal72 (Jul 10, 2016)

I guess the undersized shed kit floors are a common theme. The 2x4 joists didn't surprise me, but the 24" centers did.

I have added the third 4x4 beam in the middle and gone to 12" centers. 

I will load the hollows of the cinder blocks with my leftover screenings.

The only recommendation I didn't do was to have the outside 4x4s line up underneath the rim joists at the front and back. I have a 12" overhang front and back.

The instructions say to toe-screw each joists to the 4x4 beam. Wondering if I should also PL Premium the joists to the concrete block? 

Finally, should I be gluing the floor to the joists or just nail.

I have a feeling i will have more questions as I start to build vertically!
Thanks all!


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