Replies

1. 
   BobKovacs | Aug 25, 2003 07:20pm | #1

   SOunds like you're talking about a frost-protected shallow foundation.  I would think the stem wall being formed above the slab should be able to be poured level.  Whether it's poured level or following the slope of the slab, it'll need to be formed inside and out, and the stakes and inside forms will need to be pulled prior to finishing the slab.  Especially if your frost line is deep, the monlithic pour can save you some big $$- as long as you can find a good contractor who knows how to excavate for it, and insulate the slab properly.

   Bob

2. 
   Redfly | Aug 25, 2003 07:26pm | #2

   Yes, the lip can be level relative to the slab, simply by using a form cut at the angle of the sloped area.  However, we prefer to pour the slab and apron later, after framing and drywall are complete, in the interest of protecting the uncured slab from damage during the building process.  After the footings and stem walls are poured, we place and compact the fill material, which provides a surface to work from.  Later, when the shell is complete and we're ready for other flatwork, we pour the garage slab at the same time.

1. 
   brownbagg | Aug 25, 2003 09:08pm | #3

   Different area has different method of contruction, around here we have no frost. Everything is poured with a mono foundation. But we always pour the slab level so there is no purpose of having sloping studs. This is one method I really not clear on. Why would you want the slab to slope.

1. 
   Redfly | Aug 25, 2003 09:33pm | #4

   Here in the PNW, we always slope garage slabs toward the driveway, the reason being drainage.  When it rains or snows,  a car and its tires can hold quite a bit of water, which ends up on the garage floor.  Also, water from driving rains sometimes gets under the garage door, and if the slab wasn't sloped, could pretty much flood the garage. 

   Some people say they hose out their garage too, which I can't understand.  With all the junk in my garage I can barely get 1 car in my 2 car garage - how could I ever hose it out??

1. 
   BobKovacs | Aug 25, 2003 09:52pm | #5

   Maybe if you hosed it out every once in a while, you'd hose out some of the junk with it....lol.

2. 
   DaleS | Aug 26, 2003 07:26am | #12

   Thanks very much for your detailed reply!!!

3. 
   sungod | Aug 25, 2003 11:49pm | #6

   Here in Southern Calif. its done both ways.  Those done in one pour have a big ugly crack down the center of the garage. 

   I suspect the dirt under the slab always shrink away from the underside of the slab when it dries out.  20 feet of slab supported only on the ends will crack in the center.

   The better builders have the slab "float" and not tied to the footings.  They pour the slab after the structure is built.  Concrete curing in shade has less cracks.  Additional saw cuts are done to make 10' squares.  Also the slab is gently slopped out too.

4. 
   WorkshopJon | Aug 26, 2003 12:13am | #7

   "When I contacted a contractor who does monolithic concrete pours, he said he would not recommend it because the slab is poured with a slant which in turn requires the studs on the plate to cut an angle reflecting the slab's slant thus increasing costs."

   Dale,

   Way cheaper to go with a monolithic.

   Here are some pics of the garage I had built ~year ago. It has a sloped monolithic slab. The slab was poured with a level curb. All the wall studs are the same length. These types of slabs are the way to go if the garage will be unheated and detached. From what I saw during construction, the perimeter went down about 12", had double perimeter rebar, and I think 2" x 4" steel mesh for the slab.

   The reason for the slope is so that you can wash cars in the winter, as well as hose it clean.

   BTW, I live in Wisconsin, and the ground heaves alot. These are the norm.

   Jon

   Edit: The entire slab was poured about 10 days prior to erecting the building.

   
   

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   Edited 8/25/2003 5:15:52 PM ET by WorkshopJon

   
   

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   Edited 8/25/2003 5:16:34 PM ET by WorkshopJon

1. 
   DaleS | Aug 26, 2003 07:33am | #13

   Thanks very much  for the reply including the pictures. The underlying ground here is sandy soil.

5. 
   Piffin | Aug 26, 2003 02:56am | #8

   We do monolithic slabs with level wall curb and scoop at doors for garges that runs back maybe three or four feet but not whole slab.

   A big consideration when doing monos is the soil. placing one over clay will cauise problems, cracking not the least of them. You want a good 18" of compacted gravel.

   .

   Excellence is its own reward!

1. 
   brownbagg | Aug 26, 2003 03:33am | #9

   its really werid how different parts of country have different methods. Out of thousand of concrete pour I have witness, I have only saw two that used a gravel base. It just not done here. I guess there no really wrong way.

1. 
   Piffin | Aug 26, 2003 03:50am | #10

   You don't need it down there.

   There are two main reasons for the gravel.

   One is to provide firm footing instead of clay. Pour on clay and the building is likely to sink at least a little and as someone else said, the drying shrinking clay can cause cracks in the crete. On you sand in Florida, you have an even base tthat acccepts the loading better than the clays will.

   The other reason is that gravel will let water run through and out so that moisture is not retained in the underlying soil. Retained moisture up here will freeze and damage the footing or slab.

   Again, your sand will not hold onto that water and even if it did, you have no frost to worry about. .

   Excellence is its own reward!

2. 
   DaleS | Aug 26, 2003 07:23am | #11

   Thanks very much for the reply!   The foundation would be basically over  sandy soil base.

3. 
   DaleS | Aug 26, 2003 07:37am | #14

   Thanks very much for your reply. The ground here is is essentially sandy so no real need for gravel I would think.