PHPP Ground Sheet(s) - areas for heated basement that's partially at grade

[Markus Kolb]

Wondering if anyone has dealt with a heated basement, part of which is at grade (in this case, about one quarter of it, at the corner of an almost square footprint) and part of which is below grade. Do I use just one ground sheet and treat it as a heated basement, or do I split the slab into two areas (along the diagonal dividing line?) and treat one portion as a heated basement and the other as a slab-on-grade? Quite likely we'll use perimeter insulation (the kind that projects out horizontally below grade) at the on-grade portion, but not at the below grade portion...

Thanks & cheers,

Markus

[Adam Cohen]

Markus, that is what I have done.  I did some research on this as we have mostly walk out basements here.  In a typical square walkout say 30 x 40 with full height fill at the 40' dimension,. tapering on both 30' dimensions and walkout on the last 40' dimension, I found that the "slab" effect only went back about 10' so my projects I divided the ground based on this type of 2/3 1/3 spit - hope that helps.

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Adam Cohen
Certified Passivhaus Consultant - North America and Europe

Registered Architect, LEED AP, NAHB Green Professional

Design/Builder of the First US Passivhaus Public School Building

2012 VSBN Green Designer of the Year

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