Insulating existing slab on grade – need for sleepers?
After completing a strategy for insulating my slab-on-grade floor (which sits on sand ONLY) as part of a major building renovation in Zone 5a, I discovered the GBA construction detail for the same situation here: https://www.greenbuildingadvisor.com/cad/detail/treated-2×4-sleepers-two-layers-1-12-rigid-insulation#ixzz46QEEMp00
The GBA solution calls for treated lumber sleepers in each layer of insulation.
a) Given the high compressive strength of XPS, what purpose is served by the sleepers?
b) In my project, we need to do some leveling of sloped floors (as much as 1″ over 9 feet). We’ve thus far called for pouring a yet-undetermined cementitious material for leveling, then installing the insulation as described above. Do you have an alternative solution to suggest?
GBA Detail Library
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