Replies

1. 
   rez | Mar 07, 2007 04:03am | #1

   Greetings dc,

   This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.

   Perhaps it will catch someone's attention that can help you with advice.

   Cheers

    

    

    

   every court needs a jester

2. 
   Link | Mar 07, 2007 04:18am | #2

   I really don't know anything about a "floating" slab but all the slab on grade foundations I've seen have an insulated foundation wall around the perimeter that goes down 4 feet or more here in the north east to keep the ground under the house from freezing.  I couldn't imagine anything larger than a tool shed "floating".  And, even those have to be jacked up on one side or the other as they settle unevenly.

   I suppose you could do a floating slab somewhere where the ground never freezes.

   Anyone else want add their $.02 ...

3. 
   Catskinner | Mar 07, 2007 04:23am | #3

   Slab on grade can be done successfully anywhere you would build a house with strip footings and stemwalls for a joisted floor.

   The key is to do it right, which is probably the subject of an entire book, most of which will be written here momentarily if I make one more sweeping generalization. <G>

   Whether or not it is the cheapest way to go has much to do with the quality of native soils, the level of groundwater, how much change in elevation on the native grade across the footprint of the house, the desired FF elevation, and many other factors. Like how dependable is your plumber. <G>

   I would not assume that it is the cheapest way to go without more details.
4. 
   jlpk1500 | Mar 07, 2007 05:50am | #4

   My house is northern wi as well. 1 story ranch on slab(although 2 walls were poured concrete with earth up to soffits) so it looks like a walkout basement with no 1st floor. Built in 79 and I've lived in it since 99 with no problems, and actually adding on to it right now. Front walls are 4ft frost walls and back and side are 8ft walls to roof with 2x framing for insul and drywall.

1. 
   dccarp | Mar 07, 2007 06:20am | #5

   Thanks for the responses.  As far as a "floating" slab, that is what we call it up here in nort wis.  Lots of garages and some houses are placed on floating slabs:  typically stop soil is scraped off, LOTS of sand is brought in and compacted, slab with twelve inch grade beam is poured.  I suppose people say "floating" because it certainly is being lifted by frozen ground in the case of an unheated garage.  With two inches of foam underneath and the heat on, my guess is that frost heaving is minimal to non-existant.  I looked in the uniform dwellin code for wis and discovered that this is an allowable foundation for a new home.   We have only had code enforced on new homes for a couple years now up north. 

   As far as what's the cheapest, I'm assuming a flat lot.  With the slab you got the foundation and the first floor all in one fell swoop, with minimal excavation and site work.  You could even stain the 'crete for a low cost finish floor. 

   Any other thoughts responses to this stuff? 

1. 
   1muff2muff | Mar 07, 2007 07:58am | #6

   Currently building a rancher on a raft slab, over 20' of preloaded sand. Slab is 20" thick with 15" thickenings around the outside and thru the center 3 times. One 12"x12" grid of 10m bar and one 12"x12" grid of 15m bar, with 2,  15m bars in each thickening.

   Hope it dosen't move.

1. 
   r | Mar 07, 2007 05:02pm | #7

   some metric to English conversion issues, I think.  I'm guessing 10m means 10mm (millimeter), or about 7/16th of an inch.  Don't know what to make of 20' of sand or a 20" thick slab.

2. 
   Catskinner | Mar 07, 2007 05:41pm | #8

   I hope the architect doesn't come tell you it isn't in the right place and you need to move it. <G>What kind of soil conditions are you bridging? That sounds like a lot of concrete and steel for a house.

1. 
   1muff2muff | Mar 07, 2007 05:59pm | #9

   It's on a flood plain 5-6' of peat over blue clay. Like a wet sponge on a mattress. 

    

   Computers are new to me, and I wish I could tap fyster. Might try a picture.

2. 
   Catskinner | Mar 07, 2007 06:31pm | #10

   That beats anything I've tried. It's been years since I've worked in the blue slime and I don't miss it a bit.Sunk any machines yet?

3. 
   1muff2muff | Mar 07, 2007 06:48pm | #11

   The preload was huge, enough for two 50'x70' barns and a house with room to drive around them. So the formwork has been on packed sand.

   No major tools or trucks lost yet, only rubber boots. We used a small dumptruck that runs on tracks to move material around the site.

2. 
   ericicf | Mar 07, 2007 09:10pm | #12

   You might get some ideas from looking at Legalett, an air heated radiant system,that comes with Structural Engineering as a package.

   You can't go wrong with a stem wall though, and a uniformly thick slab will transfer heat better than a slab with thickened beam edges .

   You are bang on with R10 rigid throughout.

   Good advice from Catskinner and the others. 

5. 
   DanH | Mar 07, 2007 09:12pm | #13

   I've heard of it being done even in Alaska.

   But there are a half-dozen different schemes, and you need to be clear (between yourself, your archie, your contractor, and your BI's office) as to which one you're using.

   True "floating slab" requires that the slab be fairly heavily reenforced, eg.

   So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
6. 
   gb93433 | Mar 07, 2007 10:21pm | #14

   If you have ever had to cut out the concrete and replace a drain line you will wish you never had one.

   Just imagine a big concrete saw coming into your home to make a mess with water included, along with some smoke from the engine.

   The concrete saw doesn't care if it cuts through linoleum.

   Then someone else comes in with a jack hammer. Then the plumber comes in and does his thing. Finally the concrete is poured back. After all of that is done then you can replace the linoleum you cut through.

   
   

   ---

   Edited 3/7/2007 2:23 pm by gb93433

1. 
   SamT | Mar 08, 2007 05:01am | #15

   Quality Trick o' the Day

   This trick is not for those who "Ghitter Done!" It is only to be used when you want a repair that will  be as good as new.

   Don't use a concrete saw on a repair job.

   A jackhammer does not burnish a slurry of old concrete dust into every open pore on the new face of the old 'crete. It also does not leave a flat ,smooth, vertical surface that does nothing to help support the new 'crete.

   A jackhammered cut in concrete leaves the face with thousands of times the micro-surface area of a sawcut. On the macro level it is also a jagged natural keyway. On the micro level it goes down to actual "cement" crystals. Put a couple of samples under a mag glass or microscope and see for yourself.

   .For best results:  Just before the pour clean the face of the cut with high pressure, then mist thoroughly. If you can't air clean, then use a hose and flush it well a few hours early, then mist.

   Leave as much existing steel in the zone as possible. SamT

   Anyone who doesn't take truth seriously in small matters cannot be trusted in large ones either. [Einstein] Tks, BossHogg.

1. 
   gb93433 | Mar 08, 2007 05:26am | #16

   Good point. The problem I would see is when you have to pull out a 4" drain line. I have had to do that twice on homes and it is no fun.