Ground moisture barrier underlayment for shed

[becket]

I am getting a 10x20 barn shed, that is delivered on permanent 4x6 skids. It will be going on bare ground (no slab), and I need to put down a moisture barrier underneath. I live in hot n' humid ne Florida. I was thinking of some kind of tarp and roofing felt arrangement. What do you use, if anything? All the wood in the shed is treated.

 

[pattenp]

I just added a 10X15 potting shed this summer for my wife that sits right on the ground and I placed 6mil black plastic sheet under it.

 

[becket]

Thanks; is that the thickest out there?

 

[IDASHO]

No. 10mil is pretty common too.

But MUCH more expensive.

 

[pattenp]

Thanks; is that the thickest out there?

I'm sure there is thicker, but that was the thickest at the Lowes where I purchased it.

 

[trbomax]

I use the blue plastic tarps under my round bales. A couple of them have been down 3 years now and are still fine.Stake them down thru the grommet holes with landscape spikes and fender washers.

 

[becket]

Good stuff, thanks all

 

[gatchel]

Use the 6 mil and layer it if you are concerned. I have done this in the past with success.

 

[bazzateer]

Go for the 6mil, tarp will degrade over time.

 

[Lhorn]

I'm thinking of doing something similar and wondered what would be the best surface to put the shed on. Specifically the shed manufacterer suggested a surface of pea gravel. Does anyone know how deep this needs to be to have solid foundation?

 

[jklingel]

Wood right against plastic is a rot waiting to happen. You are going to get water between the two no matter what. I would never put wood directly on plastic. Gravel is the way to go, IMO, about 4 to 6" deep. Either that or bricks, etc, but use something that will drain and breathe. j

 

[John in OH]

I've got to agree with jklingel, wood against a plastic vapor barrier is not a good idea.

Two better options would be to put down the 6mil vapor barrier then cover with several inches of pea gravel. This will allow the wood to "breath" and not trap moisture between wood and plastic. Second option would be to put down the 6mil barrier then use flat cement blocks (the 2" thick type that are about 8" x 12") on top of the vapor barrier and at key points along the floor joist members. This will separate the wood sills from the plastic and create a vented space between the wood and plastic to allow all to breathe. You don't want to create any type of area under the floor that is not freely vented ... you'll trap moisture, and rot and mold love that kind of environment.

 

[mlammerhirt]

What about placing the vapor barrier between the floor joists of the shed and the sub floor???

Sent from my XT1254 using Tapatalk

 

[LS6 Tommy]

Wood right against plastic is a rot waiting to happen. You are going to get water between the two no matter what. I would never put wood directly on plastic. Gravel is the way to go, IMO, about 4 to 6" deep. Either that or bricks, etc, but use something that will drain and breathe. j

X2. The shed floor studs should be at least 6" off whatever substrate you use anyway.

Tommy