Replies

1. 
   johnnyd | Sep 06, 2006 09:24pm | #1

   This is done and works well when properly designed and implemented.

   There are ready-made panels designed for this purpose (name escapes me at the moment) or, as an alternative, instead of thick, routed OSB, you can rip sleepers from 4X8 panels of 3/4" OSB or plywood, lay them with space between for aluminum plates and tubing, hook up a manifold/boiler/control system and go form there.

   Others will chime in here with more specifics.

1. 
   caseyr | Sep 07, 2006 02:23am | #4

   Warmboard is probably the most advertised of the readymade hydronic heat flooring systems. I have been told it is rather pricey. There is an explanatory website at:http://www.warmboard.com/explained.htmlThis happened to pop up during my Google search, might be interesting:
   http://www.creatherm.com/index_css.cfm

2. 
   BillHartmann | Sep 07, 2006 02:44am | #6

   With foam under it you need a solid "subfloor".But you could use 2 laysers of say 3/4 or 5/8/. The first one being contiguous and the second one being cut into strips for grove for the pex.You want to run the strips at 90* to the first layer to hold it together.

2. 
   sapwood | Sep 07, 2006 12:02am | #2

   All that router work sounds horrible. Otherwise, I don't see a problem. There must be an easier way?

3. 
   timkline | Sep 07, 2006 01:54am | #3

   what are you going to use for your finished floor  ?

   can you handle this much change in elevation between the insulation and the new floor sheathing  ?    how will this meet up with the other half of the house which isn't slab on grade ?

   here is a readily available alternative to routing:

   http://www.wirsbo.com/index.php?id=42

    

   carpenter in transition

1. 
   kje | Sep 07, 2006 02:35am | #5

   Slab sits 12" below the rest of the house. This is a 12'x23' Room. I was actually thinking of adding a layer of cement board on top and then tiling it. if not I will go with a engineered wood Floating floor.

1. 
   blue_eyed_devil | Sep 07, 2006 06:19am | #7

   Placing a "dry pack" base would be ten times easier than routing osb and laying cement board. I think I could have that 270sf done by noon, if I had a helper mixing.

   blue 

1. 
   kje | Sep 07, 2006 04:18pm | #8

   How thick would the dry-pack need to be? I have never done that before though I've seenit done in bathrooms. Thats just plain mortar with a small amount of water right?

1. 
   timkline | Sep 07, 2006 06:25pm | #12

   you need at least 1" to 1 1/4" of mud on TOP of the radiant tubing.

   so let's say the OD of the tubing is 5/8" and it is stapled to the top of the subfloor. that means your mud depth from the top of the subfloor will need to be 1 5/8" to 1 7/8".

   are you looking to bring this floor up 12" to meet the rest of the house ?

   how about up 5" to give you a 7" step  ?

   doing this would simplify everything by allowing you to frame over the existing concrete with wood framing with insulation, plywood subfloor, etc.

    carpenter in transition

2. 
   timkline | Sep 07, 2006 05:34pm | #9

   blue,

   i know you are supremely talented, but 270 sf of mud bed by yourself with one guy mixing for you ?

   you would have to be Clark Kent to achieve that.

   i completely agree that a mud bed beats the routing deal, but it's a lot more than half a day for two guys.  especially if it needs to be level and or flat.

    carpenter in transition

4. 
   NRTRob | Sep 07, 2006 05:39pm | #10

   How much height do you have to play with for a build up?

   -------------------------------------
   -=Northeast Radiant Technology=-
   Radiant Design, Consultation, Parts Supply
   http://www.NRTradiant.com
1. 
   kje | Sep 07, 2006 06:14pm | #11

   Total build up including Radiant barrier, tubing, and finish floor wil be 2-1/2 ".

1. 
   NRTRob | Sep 07, 2006 06:41pm | #13

   Ok, assuming you need 3/4" for your finished floor, we only have 1.5" to work with.If it's a floating floor, you *might* be able to do a 1/2" rigid foam, with 1" of thin pour, using 3/8" pipe (NOT 1/2") at 6" o.c. That's pushing it though, most thin sets are 1.5" thick. I have heard some people saying 1" worked for them.. but I cannot swear in a court of law that it's ok.Otherwise, you could strap the slab with 1x3's 16" o.c. and use 3/4" of rigid foam in between, then run strips of 3/4" plywood perpendicular to the strapping w/spaces between, staple down plates.. kind of like your routing plan. Might be tricky though since you will only be able to screw down to the strapping.You could do the sandwich directly on top of the slab, but then obviously you have some additional downward loss to deal with.Personally, I'd probably go with a thick carpet and pad, and do radiant ceiling or radiators. Or 1" of rigid foam with a 1.5" thin pour using 1/2" pex at 6" o.c., and do a polished concrete finish floor, which would be pretty sweet.Don't waste your money on "radiant barriers" here. You want rigid foam.-------------------------------------
   -=Northeast Radiant Technology=-
   Radiant Design, Consultation, Parts Supply
   http://www.NRTradiant.com