Replies

1. 
   JIm_R | Dec 04, 1999 05:11am | #2

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   Here are some other links that seemed more logical to me than the article in Journal of Light Construction

   http://www.oikos.com/esb/43/foundations.html

   http://www.light-power.org/builders_guide/05_foundations/5-16-body.htm

2. 
   Guest_ | Dec 04, 1999 07:56am | #3

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   If you use the pink foam use foamular250, or some other brand that has a compression rate of 25 psi. Use extruded polystyrene not exspanded.

3. 
   Rob_Damico | Dec 06, 1999 06:49pm | #4

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   Owens Corning recommends their Foamular 150 (15 psi) and 250 (25 psi) for such applications, but I have an even more construction oriented question. We've got a large basement apartment to build in an existing house with half the existing slab on-grade and basement has always bee dry. Building Dept wants a total R value of 10 on that floor, so we need 1-1/2" extruded polystyrene.

   Question is the flooring assembly - Can I simply apply 5/8 plywood over the insulation by firing pins through or must I put down 2x2 sleepers between insulation panels to support the plywood. Finished flooring will be VCT or carpet. Thank you

4. 
   Guest_ | Dec 06, 1999 08:50pm | #5

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   Rob, 1-1/2-inches of extruded polystyrene will not give you R-10. Extruded PS has an R-5 per inch value.GeneL.

1. 
   Guest_ | Dec 06, 1999 08:54pm | #6

   *Take a look at this post in JLChttp://www.jlconline.com/forums/techniques/messages/3511.htmlIf that isn't it , there are several other posts in that forum about insulated slabs.Damn ! got to go take Joe's "link lesson" over again, sorry .

1. 
   Guest_ | Jan 16, 2000 06:00am | #8

   *RichardI used an insulated slab in my garage. The back part of my garage is a wood shop. I hired an architect to design the garage and he did the specification for the insulated slab. He called for 2" Polystyrene insulation under the concrete. The insulation was placed installed in sort of a 2' ring around the perimeter of the outside walls of the garage. This keeps the cold from radiating from the outside. Also the walls of the garage bear on the foundation blocks not the slab. This way the slab does not extend to the outside of the building where it will be exposed to the cold Michigan winters we have. I know this works. I have an thermal camera (FLIR) at work, you know the same kind the military uses. I checked out my slab on a cold day around Christmas. The slab was pretty much the same temperature as the air in the garage. The only place the slab was cold was where my concrete contracter screwed up and ran the slab to the outside where my door is. With the camera I could see a significant difference in temperature at that point and radiating inwards for about 3 feet.After about 3 years I have had no problems with cracking or sinking. If your slab is already poured, I would think you could imbed some foam in thinset or adheasive and use concrete backer board over the foam before setting your tile. Just make sure there are no gaps under the foam. This would also take care of "insulating" your tile from potentially cracking if the slab cracks as is common with pipes underneath. I have not seen this done but I don't see why it wouldn't work.Hope this helps.Tim

5. 
   Guest_ | Jan 16, 2000 06:00am | #7

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   Any ideas as to the best rigid, and thickness for insulating a slab, on grade? It is for a bathroom and tile floor. (Can you say cold feet?) No money for radiant floor heat.
   Also, isn't there a special foam for this type of application, to withstand compression from the concrete?

1. 
   Guest_ | Dec 03, 1999 09:48pm | #1

   *Hi RichardA while back someone here at Breaktime suggested this site for some good info...(Journal of Light Construction) http://www.jlconline.com/jlc/archive/foundations/frost_protected_slab/page1.html...Sorry, I don't know how to post this as a link.Check it out. Browse through the pages. It looks like they are using Styrofoam SM (blue), either 1.5" or 2.0". I'm thinking of doing it this way for my garage floor. I'm new to this but I believe Styrofoam SM was designed to handle compressive loads from concrete. Maybe wait for some insight from other guys who've had experience with it.Hope this helps you out.Gaby