Replies

1. 
   Piffin | Mar 21, 2009 02:23am | #1

   both terms mean the same thing to me. Maybe clarify what you see as the difference.

   Climate, ground water, and soils types are major considerations.

   Also, is this attached to a house and what type foundation there.

    

    

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2. 
   silvertip | Mar 21, 2009 02:24am | #2

   Not really understanding your question?

3. 
   Danno | Mar 21, 2009 02:42am | #3

   Are you talking about a "turn-down" slab where the edges of the slab are turned down and the whole thing is poured as one and looks sort of like a shoe box lid? versus a slab poured between footings and stem walls with the edge of the slab touching the insides of the stem walls (which are usually laid-up block)?

1. 
   Marson | Mar 21, 2009 03:05am | #4

   Round here a unattached garage gets a pad of granular, compacted fill. Then a slab gets formed on that with 10" x 10" footings around the perimeter. Much cheaper by far. The only time we would put frost footings is if the garage is attached to the house. Foam is only necessary if you are heating it. That's the way it's done in these parts.

1. 
   Danno | Mar 21, 2009 03:17am | #5

   Well, Mzinga screwed up and deleted my reply to you, so I'll try again: around here I know that a guy I talked to was very ticked because he wanted to build a cheap garage, but the building dept. required footings below the frost line (42") and stem walls and so on, pretty much killing his plans for "cheap." 

2. 
   redtoolbox | Mar 21, 2009 03:23am | #7

   to clarify: it is a detached garage. I was considering a frost-protected shallow slab. Which looks like an upside down shoe box lid with hard foam undeneath it maybe 22" deep around the perimeter. Or a single pour monolithic slab dug 48" inches around the perimeter. thanks for your input.

1. 
   Piffin | Mar 21, 2009 03:40am | #9

   Obviously the shallower is less expensive. It also happens to be a monolithic slab, mono meaning ONE single pour. The other option shaped like an upside down U can be poured monolithically or in 2/3 steps. mono pour there refers to the method by which it is formed and poured, rather than the type of foundation it is. Verb vs adjective sort of thingJust to clarify things.If this is a large building or less stable soils, you definitely want the deeper footing, but for a basic garage on good soil, the floating slab is fine and dandy - if the local AHJ is OK with it.As soils get less stable or as water is common in the subsurface, a floating slab will float more, and be more likely to crack or tilt. With no site specific info, that's about as much as I can say there. 

    

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2. 
   Marson | Mar 21, 2009 03:41am | #10

   Why such deep footings for a garage? This is what my BS department requires: http://www.duluthmn.gov/building_safety/general/Unattached%20Residential%20Garages%20Packet%20%202007.pdf. Of course, yours might be different story.

4. 
   Piffin | Mar 21, 2009 03:23am | #6

   a conversation requires replies from you....like - Tag, you're it!

   ;)

    

    

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   Taunton University of Knowledge FHB Campus at Breaktime.
    where ...
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1. 
   BoJangles | Mar 21, 2009 03:26am | #8

   See what I mean???   ;)

1. 
   Piffin | Mar 21, 2009 03:42am | #11

   figured he needed a nudge after two hours and nada.
   it's funny how often we get questions here from folks who never follow up. They read the reply and questions and disappear into the vapours. 

    

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1. 
   redtoolbox | Mar 21, 2009 04:01am | #12

   I'm still here. Just soaking it in and processing.

1. 
   Piffin | Mar 21, 2009 01:51pm | #14

   So,do you know what kind of soils and ground water conditions you have? 

    

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2. 
   redtoolbox | Mar 21, 2009 04:51pm | #15

   The soil is a mix of sand and clay. It gave nice results for a perk test. Not too hard not too soft. And ground water is not a problem. Sorry for delayed response. I appreciate your advice. You all have been a great help in the past too. This is a great forum. Edited 3/21/2009 9:52 am ET by redtoolbox

   Edited 3/21/2009 9:57 am ET by redtoolbox

5. 
   oops | Mar 21, 2009 04:59am | #13

   I'm not sure of exactly the type foundation you a referring too, but it sounds similar to what we use here in Texas almost 100% because it is less expensive. It's what we call a monolithic slab. The beams/footings are poured monolithically/at the same time as the slab.

    I don't know what your frost depth is or what you soils are like. We don't have to consider insulation or frost depth at all. Our problem is heavy clay soils which require substantial reinforcing. 4#5's in beams (int. & ext.) and #3's 18"o.c. both ways in the slab.(min). Most, now days, are engineered post- tension systems using cables that are tensioned a after specific length of time after the foundation has been poured.

   My guess is that if you have a frost line much deeper than 12"to18", this type foundation will be problematic and not necessarily economical if you are not accustom to this type construction.