Can you thermal isolate a concrete podium?

[JVK2060]

Hi Everyone,

I am working on a 4-story wood framed residential over a 2-story cast-in-place concrete podium. The residential levels and the parking are separated by a concrete transfer slab. The project is nearly finished with the design phase when we recently received some sustainability guidelines from the owner. One such requirement is to provide thermal isolation between residential use spaces and the parking.

Has anyone coordinated thermal isolation for a concrete podium or have come across this situation and what was used to resolve the issue?

A few recommendations that came from the building envelope consultant was to sandwich insulation between the concrete slab and the wood framing. Another suggestion was to provide a thermal break between the concrete slab and the tops of the concrete walls and columns supporting the slab. Neither of these seem feasible as the connections of the wood framing to the concrete slab and the rebar from the slab to the columns would disrupt the thermal break.

Thanks,

JVK2060

 

[jayrod12]

Wood itself is a pretty decent thermal break. You should ask if you put insulation between the flooring and the slab only, but allow the wood framing to continue to the top of concrete whether they'll accept that. Often the intent of thermal breaks is to minimize the potential, but elimination of all thermal bridges is usaully considered infeasible.

 

[Craig_H]

We generally look at R-value per inch of wall thickness. In this case, I would imagine that one can consider the walls to also insulate in the vertical direction. Perhaps insulating the walls for the bottom portion would provide enough insulative value of the total assembly that your framing can bear directly on the concrete? As Jay said, wood itself is practically insulative when compared to the typical thermal bridges of steel and concrete.

High compressive value insulation does exist and I have considered it in the past. If I recall correctly, I had some reservations about the compressive resistance being measured at a relatively large plastic deformation. I was worried that in reversing load situations (like a shear wall), that the insulation would eventually crush into a hogged shape and leave the shear wall rocking. I'd be interested to hear if anyone has successfully used it to form a uniform thermal break. In the situation I am recalling, I was able to convince the architect that the wood framing was sufficiently insulative that it could be considered a thermal break itself.

 

[Celt83]

typically you insulate the transfer slab soffit above the parking, a true thermal break isn't possible as the transfer slab is the floor for the first level of residential.

Insulation between the slab and supporting walls/columns sounds like is a terrible idea.

 

[bones206]

When I think of the word "sustainability", I often think of concrete parking garages

 

[JLNJ]

http://www.armatherm.com

This is what we used under our freezer columns recently. Seemed to work out. No complaints from the contractors. You might be out on your own Idaho in terms of load path and installation details, but there might be a way to structurally get them to work.