l53 slab insulation

[Joey Grimes]

Been looking over nyles plans for insulating slab they show 2 inch blue Styrofoam around perimeter of slab I'm confused surely the foam is not exposed ?

 

[YellowHammer]

The problem is that during the winter, if the edges of the slab gets cold, the water vapor in the kiln chamber will condense on the slab where it is cold.  So there will be a band of water puddled all round the edge of the slab, on the inside of the kiln.  I know because this happens to me in the dead of winter.  So the key is to keep the edges of the concrete slab the same temperature as the rest of the slab, so Nyle recommends putting foam insulation around the edge.  I simply piled a bunch of dirt around the edge, which works OK except when it is extremely cold.

[GeneWengert-WoodDoc]

In northern climates, it is called perimeter insulation.  As stated by YH, it is to keep the slab warm enuf.  If there is any of the concrete wall exposed to outside air, it also needs to be covered.  Usually, a narrow trench about 2' deep is dug around the perimeter and then 2' wide insulation is inserted.  Under the slab, the soil is dry and an excellent insulator, but wet soil near the edges is a poor insulator. Concrete is a poor insulator too.  So, even in moderate climates, this insulation is a very important feature.