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Discussion Starter · #1 ·
I am building a shall shed 15'x8' for storage. I was wondering if using 1/2" OSB will OK for a floor? The Joists support system will 12" on center on top of concert blocks about 2" off the ground.
 

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retired painter
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With the joists on 12" centers it might be ok - 5/8" OSB would be better. Will there be plenty of ventilation under the shed?
 

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JUSTA MEMBER
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Warning.

Any water ever gets on your OSB, you have a pile of garbage.

I suggest going to real PLYWOOD (CDX EXTERIOR GRADE, OR PT) , it is made different and withstands water.


ED
 

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I would go with pressure treated plywood.

On my shed I did double 1/2” standard plywood and painted it. Lasted about 5 years.

Removed and replaced with 1/2” pressure treated plywood and it’s going strong for 10 years now.
 

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Discussion Starter · #9 ·
Thanks All! I will use OSB for walls/roof and PT plywood for floor. Will paint the base foundation structure to ensure longevity, hopefully it will last until i'm dead!
 

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Pressure treated plywood is full of knots and voids in the plys.
Advantech is T & G and will give you a rock soild floor with no voids for bugs to get in.
 
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retired painter
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I had never used Advantech until the addition on my son's house. It took way too long to get it dried in but the Advantech held up great, other than discoloring you couldn't tell it ever got rained on. I was really impressed!
 

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Property Mgt/Maint
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Looks like ok for oil/solvent based coatings, no water based
http://www.huberwood.com/assets/user/library/AdvanTech_and_coatings_v2.pdf


Another option would be to staple a layer of poly over the joist tops just prior to laying the sheathing. It should do a good job keeping ground moisture vapor from passing into the sheathing. Cheap insurance and easier than painting.


And we are using treated joist?
And treated lumber rated fasteners.
 

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Discussion Starter · #16 ·
Yes, the base structure will be all treated lumbers sitting on top of concert blocks, will use simpson strong ties as the hardware. Should be good enough for a small structure.
 

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Just to throw out another option,
I've built 2 sheds,

First I did on concrete blocks with PT 2x with CDX plywood. Was a pain to level the blocks, it raised up the floor so it sat taller, and needed a bigger ramp and when I added up the cost and the PITA effort to level the blocks in my yard, when I built my shed in my new house I did it differently.

I paid to have a concrete pad put down with anchor bolts. it cost more, but i didn't have the need to do any of it myself, deal with the leveling etc, and I'm happier with the finished product. I also had him pour a little ramp up to it.

Now the nice gentlemen who did this poured it out of square...which pissed me off on such a small pad of 10x12.. but I still am happier with the shed.

I also had all the lumber delivered along with vinyl siding, and roofing material etc, to save myself time and effort for all that crap.
 

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Yes, the base structure will be all treated lumbers sitting on top of concert blocks, will use simpson strong ties as the hardware. Should be good enough for a small structure.

Yes, and any nail or screw going into treated lumber needs to be coated and rated for treated lumber.
The current treated lumber will rot uncoated fasteners clean off in short order.
 

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JUSTA MEMBER
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There is no excuse for something that small to be out of square, unless you are talking less than a quarter inch.

Anything more than a quarter inch, is just lazy.




ED
 

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retired painter
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I find it interesting [and confusing] that they specifically say an oil base sealer will void the warranty but oil base paint and your choice of top coat [oil or latex] doesn't.
 
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