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Florida Shed Insulation

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TractorJeff

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Talking to a friend of mine near Panama Beach yesterday. The new Shed which will be used a "SHE SHED" which is going to be heated and cooled. The questions arose about Vapor Barrier and Insulation? We are both Northern boys and from what little I have read the vapor barrier is on the outside down there?
 
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Hank11

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If you are asking about paper faced fiberglass insulation, the paper generally goes on the inside in warm humid locales. Typically from inside out - drywall screwed to 2x4 studs, paper backed fiberglass stapled to studs, sheathing, house wrap, siding. This construction detail is certainly not sufficient for a big storm or hurricane.

And there is more to consider. Is there water in the building or anything that might produce water vapor? If not this may not matter. If it is constantly heated and cooled it will likely be drier inside than out all the time. Is it?

And its Florida where they have special insects and moisture. Its worth checking with a local.
 
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TractorJeff

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Hank11 said:
If you are asking about paper faced fiberglass insulation, the paper generally goes on the inside in warm humid locales. Typically from inside out - drywall screwed to 2x4 studs, paper backed fiberglass stapled to studs, sheathing, house wrap, siding. This construction detail is certainly not sufficient for a big storm or hurricane.

And there is more to consider. Is there water in the building or anything that might produce water vapor? If no,t this may not matter. If it is constantly heated and cooled it will likely be drier inside than out all the time. Is it?

And its Florida where they have special insects and moisture. It's worth checking with a local.
Click to expand...
In the first sentence, You say the paper goes on the inside?
Then you state the paper should be on the outside facing the sheathing? This part I understand to be true because it is opposite of up Here (Northern Climate).
I will talk to him in greater detail on local Codes.
 
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mike93lx

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Vapor barrier to the warm side keeps warm moist air from contacting the cold air. I'd expect that to be on the exterior in FL.
 
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75gmck25

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Does your budget allow for a spray foam contractor? Its a small job and that would make it less attractive for them, but it seems so simple that they might take it as a side job. They can spray the walls and the roof deck and you will have a completely insulated space. You will usually then have to cover the foam with sheetrock or other flame barrier to meet code (maybe not for a shed?).

I'd also figure out ahead of time how you will insulate the floor and prevent moisture infiltration. Most of these sheds just have a plywood floor on joists, and that doesn't stop insects, moisture or air infiltration.
 
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mike93lx

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75gmck25 said:
Does your budget allow for a spray foam contractor? Its a small job and that would make it less attractive for them, but it seems so simple that they might take it as a side job. They can spray the walls and the roof deck and you will have a completely insulated space. You will usually then have to cover the foam with sheetrock or other flame barrier to meet code (maybe not for a shed?).

I'd also figure out ahead of time how you will insulate the floor and prevent moisture infiltration. Most of these sheds just have a plywood floor on joists, and that doesn't stop insects, moisture or air infiltration.
Click to expand...
For a small space, diy with froth packs could make sense
 
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Hank11

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If it might ever get flooded, I'd build it out of concrete. And generally any wood near the ground is a bad thing. A slightly elevated slab or a slab and short knee wall maybe?

I like foam, but wonder what you do with it after the wall floods and needs to dry out?
 
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Old Man Roger

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tinmanwpk

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Clear as mud.​

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R806.5Unvented attic and unvented enclosed rafter assemblies.​

Unvented attics and unvented enclosed roof framing assemblies created by ceilings that are applied directly to the underside of the roof framing members and structural roof sheathing applied directly to the top of the roof framing members/rafters, shall be permitted where all the following conditions are met:
  1. 1.The unvented attic space is completely within the building thermal envelope.
  2. 2.No interior Class I vapor retarders are installed on the ceiling side (attic floor) of the unvented attic assembly or on the ceiling side of the unvented enclosed roof framing assembly.
  3. 3.Where wood shingles or shakes are used, a minimum 1/4-inch (6.4 mm) vented airspace separates the shingles or shakes and the roofing underlayment above the structural sheathing.
  4. 4.In Climate Zones 5, 6, 7 and 8, any air-impermeable insulation shall be a Class II vapor retarder, or shall have a Class II vapor retarder coating or covering in direct contact with the underside of the insulation.
  5. 5.Insulation shall comply with Item 5.3 and Item 5.1. As an alternative, where air-permeable insulation is located on top of the attic floor or on top of the attic ceiling, insulation shall comply with Item 5.3 and Item 5.2.
    1. 5.1.Item 5.1.1, 5.1.2, 5.1.3 or 5.1.4 shall be met, depending on the air permeability of the insulation directly under the structural roof sheathing.
      1. 5.1.1.Where only air-impermeable insulation is provided, it shall be applied in direct contact with the underside of the structural roof sheathing.
      2. 5.1.2.Where air-permeable insulation is provided inside the building thermal envelope, it shall be installed in accordance with Section 5.1.1. In addition to the air-permeable insulation installed directly below the structural sheathing, rigid board or sheet insulation shall be installed directly above the structural roof sheathing in accordance with the R-values in Table R806.5 for condensation control.
      3. 5.1.3.Where both air-impermeable and air-permeable insulation are provided, the air-impermeable insulation shall be applied in direct contact with the underside of the structural roof sheathing in accordance with Item 5.1.1 and shall be in accordance with the R-values in Table R806.5 for condensation control. The air-permeable insulation shall be installed directly under the air-impermeable insulation.
      4. 5.1.4.Alternatively, sufficient rigid board or sheet insulation shall be installed directly above the structural roof sheathing to maintain the monthly average temperature of the underside of the structural roof sheathing above 45°F (7°C). For calculation purposes, an interior air temperature of 68°F (20°C) is assumed and the exterior air temperature is assumed to be the monthly average outside air temperature of the three coldest months.
    2. 5.2.In Climate Zones 1, 2 and 3, air-permeable insulation installed in unvented attics on the top of the attic floor or on top of the ceiling shall meet the following requirements:
      1. 5.2.1.An approved vapor diffusion port shall be installed not more than 12 inches (305 mm) from the highest point of the roof, measured vertically from the highest point of the roof to the lower edge of the port.
      2. 5.2.2.The port area shall be greater than or equal to 1:600 of the ceiling area. Where there are multiple ports in the attic, the sum of the port areas shall be greater than or equal to the area requirement.
      3. 5.2.3.The vapor-permeable membrane in the vapor diffusion port shall have a vapor permeance rating of greater than or equal to 20 perms when tested in accordance with Procedure A of ASTM E96.
      4. 5.2.4.The vapor diffusion port shall serve as an air barrier between the attic and the exterior of the building.
      5. 5.2.5.The vapor diffusion port shall protect the attic against the entrance of rain and snow.
    3. 5.3.Where preformed insulation board is used as the air-impermeable insulation layer, it shall be sealed at the perimeter of each individual sheet interior surface to form a continuous layer.
TABLE R806.5
INSULATION FOR CONDENSATION CONTROL

CLIMATE ZONE​
MINIMUM RIGID BOARD ON AIR-IMPERMEABLE INSULATION R-VALUEa, b​
2B and 3B tile roof only​
0 (none required)​
1, 2A, 2B, 3A, 3B, 3C​
R-5​
4C​
R-10​
4A, 4B​
R-15​
5​
R-20​
6​
R-25​
7​
R-30​
8​
R-35​
  1. a.Contributes to but does not supersede the requirements in Section R402 of the Florida Building Code, Energy Conservation.
  2. b.Alternatively, sufficient continuous insulation shall be installed directly above the structural roof sheathing to maintain the monthly average temperature of the underside of the structural roof sheathing above 45°F (7°C). For calculation purposes, an interior air temperature of 68°F (20°C) is assumed and the exterior air temperature is assumed to be the monthly average outside air temperature of the three coldest months.
 
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