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Radiant floor for large truck shop

Its the subbase! The top layer of any pour or blacktop is only as good as the subbase... I've seen a tractor and heavy equipment repair place with no crack. Asked the owner what his secret, he said drainage and pack and re-pack the subbase as much you can... of course, use insulation properly.


  • kevink1955
    kevink1955 Member Posts: 79

    We are building a new truck maintanance building, it wil be a steel building with 34 feet to the ridge line building size is 48' X 100'. It will have an 8" slab and I think it would be perfect for radiant floor heat. The final design will be by the enginers but I am looking for some tips.

    The shop will see traffic from trucks that weigh up to 40 tons. My main concern is if the tubing is imbeded in the slab and the slab cracks what keeps the tubing from being sheared off at the crack?, the same thing could happen at the control joints.

    Most of the installations I have seen have the tubing tied to the reinforcing mesh and in the middle of the slab, I think any shift in the slab as a 40 ton truck rolls over a joint could cause tubing damage. What would happen if the tubing was put under the slab on top of any insulation board that may be installed. I know the recovery would be slower but the shop will be maintained at temp at all times (no setbacks) so would this work.

    Anything else to look at, I do not want to see the gas fired unit heaters at 24' that they have proposed and gas radiant tube heaters are out as the open space above must be maintained due to vehicle lifts.

    Any ideas/comments as to what to do and what not to do. I just do not want to see this get done and have problems cause the concrete cracked and took the tube with it.
  • Mike Dunn
    Mike Dunn Member Posts: 189
    shop tubing

    can be stapled to the top of the foam with no problems.
  • Darin Cook_5
    Darin Cook_5 Member Posts: 298

    A Boeing 747 can weigh up to 400,000 pounds empty and hangers have radiant floor heat in them. You will be safe.


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  • kpc_25
    kpc_25 Member Posts: 1
    How about ...

    2 pours.. insulated 4" base then mesh w/ another 4" top slab attached to the bottom layer... that way the tube is closer to the top. Responce time is faster and strength is ok...kpc
  • Rich Kontny_3
    Rich Kontny_3 Member Posts: 562

    We bid a lot of fire stations and municipal garages an if they want to be cost effective they almost always go with infared units such as CO-Ray-Vac. Don't like to chase away in-floors but doing a side by side comparison usually results in the infared being spec'd. No freeze up worries and infrared is like artificial sunlight (it heats objects)
  • I imagine,,,

    an infrared heaters install would be considerably less that tubing the floor. I just did one myself, 14,000 sq ft of sheetmetal shop with Schwenk heaters. Ran him $1500 a month for heat last winter. Seems reasonable to me.
  • kevink1955
    kevink1955 Member Posts: 79

    I know the radiant tube heaters work well but are not an option here as the entire space above the floor needs to be wide open.

    The building will have a boiler to heat an office, classroom and bathroom so why not size it for the entire building and heat the floor.

    I am just looking to insure that the tube gets done right so it will not leak in the future. Keep the ideas coming.
  • troy_8
    troy_8 Member Posts: 109
    Radiant in Truck garage

    No Problem. My own shop has 3/4" pex in the concrete. We used to get tractor trailer loads of Gypsum concrete. 80,000 on the trailer. My floor did crack after 3 years but never a problem. In fact I would stack 3 pallets high 3 pallets deep and 3 pallets wide. In a 12'x 12' space I had 160,000 lbs. Don't try this at home. Still no problem with the heat. My slab is only 5" thick with 2" polystyrene under it. We have installed many heavy equipment slabs and never had a problem. The base is the key. The engineer made me use 50 psi insulation on the last job and then 8" of 4000psi concrete. Don't go overhead.
  • JaredM
    JaredM Member Posts: 57
    Radiant Floor Garage


    I have been involved in two large garages with radiant floors. One was a truck repair shop, the other a very large bus maintenance facility (coach buses).

    The bus garage was speced out with two layers of re-bar, one at two inches above sub-grade and the other 3 inches below the top of slab. From memory it was a 10" pour. The tubing was tied to the lower layer of re-bar. That job has absolutely no cracks other than at the control joints. We avoided crossing the control joints with the tubing where possible. Where the tubing did pass the control joints we wrapped the tubing with foam insulation to allow for movement of the adjacent slabs. Only about 18" of insulation at each crossing.

    The other garage was a much smaller facility with a 6" slab and wire mesh. On that job we attached the tubing to the foam insulation and the concrete was poured over. Over the years there have been some cracks formed but no leak issues.


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  • kevink1955
    kevink1955 Member Posts: 79

    I found this on the Watts web site, it shows a pvc or foam insulation where the tubing crosses an expansion joint. Sort of makes me feel better, I was woried about slab movement breaking the tubing.


    This manual is about 80 pages long and covers all types of installations, it's a good resd
  • Ted_5
    Ted_5 Member Posts: 272
    what is your location?

    When I was an installing contractor (now I am a rep) I did a city garage that was 34,000 sq/ft with a 8" slab. We stapled the 5/8" tube down to the foam. The only time we sleeved the tube is when we crossed a cold joint, not a cut joint. This was 7 years ago. They also wanted unit heaters by every 16' tall overhead door, I could not talk them out of it. They say know, we would not have needed those. They at times bring in 12 plows and trucks from being out most of the night and have no problem melting off the equipment and maintaining heat in the space. I could send you a small power point I did on comparing this buildings heating cost to another buildings heating cost that did not use radiant floors. Be leave me, that guy who was talking about overhead radiant is way off! The pay back is easily less then 5 years. This job I estimated it being only a 3 year pay back! That is a no brainier!!

  • kevink1955
    kevink1955 Member Posts: 79

    Location is Long Island NY. I am already sold on the savings so I will not need the Power Point but thanks for the offer.

    I am not expecting any cut joints only the regular 1/2" expension joints installed when the concrete is being poured. I am concerned with the tubing crossing the joints as I feel there will be some movement that could damage the tubing. That's why I think the sleeve is a good idea.

    Going to see how the engineer designs it before I try to push any of the issues I have raised here.
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