Concrete over rigid insulation

[WWTEng]

This is for a small area inside a light well. The existing slab is to removed are replaced and the arch wants granular fill topped by 4" of rigid insulation topped by 4" of slab on grade. Will not have any access except for the occasional maintenance guy.

Should there by a layer of vapor retarder between concrete and insulation?

 

[cvg]

will the barrier prevent drainage of moisture and short out the light fixture?

 

[WWTEng]

cvg, the rigid insulation and concrete are at grad level, I am not sure how it would short circuit the light!

 

[cvg]

I guess I'm not picturing the light well properly. so the light and wiring is mounted above the slab and not in a well, why are you removing the concrete than?

 

[WWTEng]

Concrete is being removed and replaced because its an existing structure where the existing slab in the light well has deteriorated. I am assuming the reason the architect wants rigid insulation this time is for better overall thermal efficiency.

I am not actually sure about the location of the light (or even if there is one) but I would assume it would be several feet higher above this slab.

 

[tony1851]

Isn't this the architect's problem rather than yours?