Adding in-floor on an existing concrete slab

Bill B.

I have an existing 6" thick concrete workshop floor that measures 30'x30' square. It was poured over the ground without any barriers put down first. I would like to install radiant heat on top of the floor. I have 3" of space to use. What is the best way to go about installing the in-floor? What kind of insulation barrier is out there that does not use up all 3"? Is it O.K. to pour another 3" concrete slab on the existing floor? The walls are 10' high and made up of 2"x6" studs with fiberglass batts and finished with drywall. Two 3'x5' windows face west, three 3'x5' windows face south, one 3'x5' window faces east along with an insulated 7'x10' garage door and a 36"x80" service door. The north wall has no windows but does have a 36"x80" service door to the car garage.

KCA_2

What about

A radiant ceiling?

Otherwise, yes there are insulations and ways to get what you want however, do you have a high water table or is the slab on bedrock? Reason I ask is that those situations call for a larger amount (R10 or better) insulation. The water and bedrock are a heatsink. You'll be limited to an R2 with a reflectiveness to it that will insulate the radiant energy but not the conductive energy.

The radiant ceiling you'll have more control over and it'll probably end up more economical.

Just my opinion...

Hope it helps

:-) Kca

Terry

warm floors

Radiant ceilings would heat ok, but would not have the same effect in a shop atmosphere as radiant floor would, since a warm floor means; warm toes, tools, and a dry surface to work on.

mo
Terry

hot_rod

3\" is not enough

If this is a slab that sees vehicle traffic at least 3-1/2- 4" is needed, in my opinion. Anywy you could give up 5"? 1" Foamboard, tube, and a 4" pour. Or an Insultarp 1/2" and a 4" pour.

If you go to the trouble of an overpour, I think you would really want that thermal break and insulation factor.

hot rod

James_2

I would do radiant

tube heaters. ie; Reverberay. Quick and easy to install. Warms the object including the floor. Has quick recovery so no need to wait for days to warm the floor. Option #2 Baseboard heat and kick space heaters at floor level would also keep your feet warm and tools dry.

Newt Loken

Over-pour

I wonder what climate you live in. As others do, I lean toward radiant floor if at all possible. Yet important issues abound.
If heavy, vibrating equiment or vehicles would be (or ever could be in the future) located on the slab a couple of ideas come to mind. One, make sure the rating on the Extruded Poly Styrene ("pinkboard" or whatever), is adequate. Higher psi ratings are available special order (any other input here?). Two, perhaps a pattern can be developed that affords strength and some insulating ability. Rebar placed in a 24" o.c. grid and 1"-1 1/2" insulating squares (~18" x 18")placed inside the 2' x 2' openings . This would create a "waffled beam" effect (I hear aliens use this method). Also, this could be done within the center 2/3rds of the area while leaving the perimiter (the area of highest heat loss) fully protected by continuous insulation of your chosen thickness. A variation is to have that inner 2/3rds just "rock to rock", with no insulation, and no or very few tubes. Again, highest heat loss is at the perimeter. I always think insulation is a good idea, but depending on climate based heatloss, and use, I would hate to see underfloor insulation skipped all together (fear of extensive cracking). Since this would cause lower heat output due to tube spacing, etc. perhaps another quick recovery emmitter could be sprinkled in (radiant wainscotting). With mention of this last mixed media idea, do consider that many shops are used intermitently and a base temperature gotten thru high mass radiant floor combines well with a low mass, quick heat booster (just a two temp system, two stage too perhaps).
Remember pouring rock is about the only construction step you can't redo easily. 20-50 years from now how much will that energy leak cost?
Newt

hot_rod

Balance all this against

Having a professional concrete company come by and make that slab disapper for you.

A Bobcat with a breaker and a dump truck is an option. 900 square feet can disapper in a day, easily. They can also slice a few inches to allow a 2" foam to be placed.

Then you can insulate, tube and do it right! Just a thought.

hot rod

[Deleted User]

Now THAT'S...

a Jack Hammer. Wonder what it feels like in the drivers seat with that puppy running.^V^V^V^V^V^V^V^V^V^V

Wayco Wayne

I'm looking at a job that is in a home

that has a sun room on a slab that has a little room below it. I was thinking of puting down some 1/2 in plywood and stapling some pex down and pouring seveal inches of concrete over it. (The sun room is a step down into room. What problems could this have???

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Wayco Wayne

I'm looking at a job that is in a home

that has a sun room on a slab that has a little room below it. I was thinking of puting down some 1/2 in plywood and stapling some pex down and pouring seveal inches of concrete over it. (The sun room is a step down into room. What problems could this have???

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Jackchips

You will

get better responses if you go to the top of the wall and start a new thread.

Joh n Brickey

If you are not using this for cars to be parked on and just as a work shop you could,,,, lay some 2x4's on their flat side and power nail them to the floor on 12" centers and staple the 1/2" tubing to the sides of them. You should put visqueen down first as a moisture barrier and in between the nailed down 2x4's you could put down 1/2" foam. When this is all done put 3/4" plywood over the whole thing. You'll have to run a little hotter water but it would work fine.

john wood

I did my office this way.....

I rolled out the reflective bubble insulation (this is possibly the best application for the product) on the old slab, rolled out the 3/8" Kitec XPA tube and fastened it using 1/2" conduit clamps and a powder actuated nailer. Then poured 2" of 6 sack concrete with 3/8" aggregate and fiber "hair" for add'l reinforcement. As a coup 'd grace, I masked off "grout lines" with blue masking tape and applied a concrete stain.

Now I have a "pretty" floor that is a delight to live with. Sitting over it right now as I type. Keep 1F differential wall stat at 62F and even the "reptillian" wife says it is comfortably warm.

Joh n Brickey

Bill, you should use at least 1/2" foam between the 2x4's to keep the heat from going down. If you think about it you could use 3/4" foam ,that would leave another 3/4" to staple your tubing to. I did this in an existing basement and it kicks ****.

Mark A. Custis

Heat loss down



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