Building house with garage under garage?

[thedoc]

Hello. Been a while since last findings on here. I'm moving across town and building for the first time. We sold current house and my detached dream garage which I built three yrs ago.
It had in floor radiant heat. Water. Cable. Drywalled.

The new house is designed to have a garage under the main level garage. Walkout so I'm able to get an 8x9 overhead door down there on back side.
My questions are:
I'm doing in floor radiant heat again but wondering how to insulate the walls.
Stud them out and use bats. Or insulate exterior foundation walls on outside with foam board.
Guessing with prestressed ceiling I won't have a way to insulate that.
Don't want this thing to be concrete dungeon so I'll probably line the walls with something and paint the ceiling.
Living in eastern iowa gets darn cold in the winters.
Anyone have a basement garage and have this experience?
Thanks

 

[kbs2244]

I would put the insulation on the outside of any above ground concrete down to the frost line.
This will put the "thermal mass" of the concrete on the warm side in winter and the cool side in summer.
Below the frost line shouldn't matter.
You will have a costant temp there.

 

[xtremek]

I'm no help with your problem, but when you do this, make it a thread. "Cause this sounds like a fun time. There's a thread called the "Basement bike barn build" or something like that. It might have something in it. I know the barn is built in northern Michigan, so cold is every much a factor. Good luck.

 

[JeepinMike]

I have exactly that, a 2 car garage on pre-cast concrete panels with an identical sized space below it. 8' ceiling underneath, 5 sided concrete box, single 7' tall x 8'(?) wide garage door on the studded wall. I've recently drywalled ~12ft in a corner to make it easier to hang cabinets and am most of the way done building base cabinets for that space. Oh, and the space is not accessible from inside the house. Only small holes for plumbing and utilities go through the foundation wall.

My boiler & oil tank are in this same space, and I have a separate zone with a single hot water heater/fan unit (I'm sure there's a better/more proper name for it) that brings it up to temp quick enough. I usually leave the heat off, the presence of the boiler keeps it above freezing, but I'll pull the jeep in Friday night in the winter, turn the heat, and Saturday morning the jeep is warm and dry and ready to be worked on.

-mike

 

[TheGunCollector]

I have a garage under a garage. I used 2"XPS directly to the foundation on the inside, and then framed out the walls with 2x4's 24"oc, but mounted flat.

It was a pita, and probably should've framed traditional walls with either bats or blown in.

 

[Voi]

Guessing with prestressed ceiling I won't have a way to insulate that.

Can't you line the underside of the upper floor with foam? Is the pre-stressed slab going to have radiant loops in it?

I know two people with over/under garages. One did not have radiant loops in the pre-cast slab and he didn't insulate the underside so the upper garage would get a bit of supplemental heat in the winter. The slab in the lower portion had radiant loops.

The second guy has boat storage under a carport of sorts. He used some sort of insulated form to pour the slab so the boat storage ceiling is insulated. It was only a narrow single wide garage and I do not know what the span limitations of the insulated forms were.

[EDIT] Fairly certain the forms were Lite Deck.

 

[woody611]

I have a similar situation with a "garage under garage". I am planning on going the traditional 2x4 framing with bat insulation on the walls.

Unfortunately for me I didn't do enough research prior to building and snow melt from the main upper garage will drip between the panels. I had a concrete/foundation repair contractor look at it and they thought my best option would be to epoxy coat the upper floor to seal it. I was planning on just painting the underside/ceiling, but will wait until I have the seepage issue resolved.

 

[Bib Overalls]

Build your foundation and lower level walls with insulated concrete forms. Your upper level garage floor will require an engineered solution. Steel joists with a monolithic concrete floor, as used in commercial construction, would be my choice.