Potential wood floor issues in 12x16 shed

[Greensleeves420]

I am in the design process for my 12x16 foot grow shed and I am stuck on the base. The rest of the design of the structure seems to be pretty straight ahead.

What is the best way to design a wood floor for a grow room so that it will last. I do not want to use a concrete pad. I am only interested in would floor designs. Has to be insullated.

My plan so far is to put 4x4 posts flat on concrete blocks, then build the floor on the posts.
-7/16"OSB floor bottom
-2x4 Framing
-5/8 OSB floor top
-linoleum finish.

Thank you for your thoughts.

 

[bluenoserjoe]

If you us pressure treated 4x4s and then the bottom layer of your floor being pressure treated plywood then you will have a shed that will last many years to come.

 

[PE636]

That's going to be a pretty weak floor. As someone with no less than 40 thousand hours in carpentry and construction I would consider no less than 2x6 joists with a double rim (I'd go for 2x8 personally for a few bucks more) with 3/4 inch t&g plywood screwed and glued, not nailed. Nothing worse than a saggy floor. I wouldn't use osb on anything but walls and roof. Actually I would probably skip the osb walls and just use preprimed smartpanel, that would depend on how you want it to look in the end though. Consider using housewrap like Tyvek on the bottom instead of osb or something, cheaper, lighter and will minimize moisture problems whereas osb just wicks it up. Hit me up if you have any questions.

 

[Backlipslide]

Yeah, with that big of a structure sitting on it, I would recommend 2x6 as well, if not 2x8 like @PE636 mentioned.

2x4 floor joists would be okay for a small 8x8 shed but anything bigger then that should have a lil extra reinforced floor joist

 

[PE636]

Also, with a proper sized double rim joist and enough blocks (5 per side) you have no need for the 4x4s though they wouldn't be hurting anything.

 

[Backlipslide]

And I also agree 3/4 plywood for sheeting.

 

[PE636]

Also to be considered is the deeper the floor joist the more insulation you can have. I am changing my recommendation to definitely 2x8. R12 in 2x4 would probably be disappointing if you have actual cold weather in your location.

 

[Dwight Monk]

As said OSB and Particleboard do silly things if they get wet or enough humidity they don't do well for floors. I went with 4x4 pressure treated posts (as shed floor got wet sometimes when it rained hard so original floor was pallets on the concrete) and I put foam insulation in between for my floor base in my shed (keep the cold off the cement going right to the floor that way), then put plywood on top of that and got some 8' 1x4 cedar I put on top of the plywood and then used the water seal stuff on the boards.

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• Dwight Monk
• Jul 16, 2019

I thought the cedar might help with bugs, but not sure it did anything to be honest. But it looked good for awhile until it got all dirty but still really doesn't look too bad as it's been in there two years now.

 

[bluenoserjoe]

A lot of assumptions here. Lets say the 4x4 stringers are place 4 feet apart, then the 2x4 floor joists are plenty strong. As long as the bottom of the system is pressure treated everything else will stay dry. Modern insulation's would be plenty in that space unless you are way north, or south. Weather treated t+g osb sheet goods (while not the best) covered with lino (no seams) will keep the top dry. Almost all shed trusses are framed with 2x4 joists.

 

[Blew Hiller]

What are the min/max temps you expect to encounter when growing?