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  • In Floor Heating For Shop

    ok not sure if this is in the wright forum but here goes.

    last year I built a 30x40 garage. it's sitting on a foundation. the inside is filled with 3/4" clear stone. I haven't poured the floor yet or installed the 10x10 doors. I'm trying to get things ready for this. I'm putting in floor heat which will operate via an oil fired hot water tank. now for the lines I was told I will need 6 loops of 3/4" kytec. for insulation I was originally going to use the rfoil double bubble product. in doing research on this since last year I haven't found any supporting documents that show it as being very effective. two of the concrete floor finishing guys I spoke to said it was crap and that they can tell when pouring on the r foil it takes a lot longer for it to cure than on the foam board. so now I'm leaning towards using owens corning celfort 300 2" foam board. we already backfilled all around the outside of the foundation so I was going to put foam board on the inside of the foundation going down 4 feet vertical and then cover the floor area. my quesiton is can I put some going 4 feet down vertical in front of where the doors will be? will the 5" of concrete going over a 2" span of vertical foam board be a structual issue? I know on the floor itself it's suppose to be good for 30psi. is going 4' down overkill? I understand it's to prevent the frost from driving in through the wall and up to the floor. my other question is I'm going to have a drain covering the area in front of both doors. it will be about 3 feet in and 1 foot by 24 feet. I can't really insulate where the footing for the drain will be. will this be a big point of heat loss?

    oh and another thing the walls are 2x6 and 12 feet high + about 6" of foundation that will be exposed after the finished floor.

    thanks
    Jeff

  • #2
    Re: In Floor Heating For Shop

    Originally posted by jeffntanya View Post
    ok not sure if this is in the wright forum but here goes.

    last year I built a 30x40 garage. it's sitting on a foundation. the inside is filled with 3/4" clear stone. I haven't poured the floor yet or installed the 10x10 doors. I'm trying to get things ready for this. I'm putting in floor heat which will operate via an oil fired hot water tank. now for the lines I was told I will need 6 loops of 3/4" kytec. for insulation I was originally going to use the rfoil double bubble product. in doing research on this since last year I haven't found any supporting documents that show it as being very effective. two of the concrete floor finishing guys I spoke to said it was crap and that they can tell when pouring on the r foil it takes a lot longer for it to cure than on the foam board. so now I'm leaning towards using owens corning celfort 300 2" foam board. we already backfilled all around the outside of the foundation so I was going to put foam board on the inside of the foundation going down 4 feet vertical and then cover the floor area. my quesiton is can I put some going 4 feet down vertical in front of where the doors will be? will the 5" of concrete going over a 2" span of vertical foam board be a structual issue? I know on the floor itself it's suppose to be good for 30psi. is going 4' down overkill? I understand it's to prevent the frost from driving in through the wall and up to the floor. my other question is I'm going to have a drain covering the area in front of both doors. it will be about 3 feet in and 1 foot by 24 feet. I can't really insulate where the footing for the drain will be. will this be a big point of heat loss?

    oh and another thing the walls are 2x6 and 12 feet high + about 6" of foundation that will be exposed after the finished floor.

    thanks
    Jeff
    Do yourself a big favor, get a plumbing contractor involved before you pour that slab.

    You will not get the info you need on a discussion forum.
    the dog

    Comment


    • #3
      Re: In Floor Heating For Shop

      listen to the dog, save yourself loads of trouble. there are too many variables for quick answers. radiant heating doesn't work well as an afterthought. the mason, plumber/heating contractor should get together before you break ground.

      Comment


      • #4
        Re: In Floor Heating For Shop

        the guy that designed the layout for me did the training on in floor and works for the local plumbing supplier. he goes on job sites and advises people how to lay it out. that part is all sorted out. it's the decision on what to use for insulation. he says most people go with the 2" sm type board but there have been a lot of claims that the rfoil is just as good. although everything I read says otherwise.

        Comment


        • #5
          Re: In Floor Heating For Shop

          Can't help you with the in floor as I am going with overhead radiant but I am doing the floor similar to what you are considering. The idea is to have the floor as a thermal mass that is isolated from the cold. I will use 2" foil backed Energy Shield Plus . I will go a few inches under the stone on the sides just to aid in keeping the sides in place until the PL300 dries. I think going 4' down is overkill. There are no issues with the 2" span. You will want to check with the building inspector on the floor drain, it is my understanding that they are not legal now due to environmental concerns
          Last edited by wbrooks; 08-27-2007, 09:36 AM.

          Comment


          • #6
            Re: In Floor Heating For Shop

            I think the difference in the insulation you use would be wether you are trying to keep the cold from getting up into the slab or the heat going down into the soil. The foam will keep the cold down but the foil would be better for the radiant heat.

            Can't tell from your location just how cold it gets. Cornwall, England?

            Comment


            • #7
              Re: In Floor Heating For Shop

              I was thinking Cornwall, near Ottawa, Canada = COLD!!

              Comment


              • #8
                Re: In Floor Heating For Shop

                yup it's Cornwall, Ontario which is about an hour east of Ottawa

                I spoke to the building inspector yesterday and he's talk to a lot of people with in floor and all the ones that used the 1/4" thick foil blanket are not happy with the results. I think I've made up my mind and going with the 2" owens corning celfort 300 which is good for 30psi. he agreed that 4 feet down the sides was a little much and a lot more work since the gravel is already in there. I will put the 2x8 sheets horizontal on the inside of the foundation. this will give me about 1' below the floor grade and will reach to the top of the foundation wall. because of the slope on the floor from the rear of the shop to the drain in front having 3" there will be 3" of insulation exposed at the rear and 6" at the drain. I will have to make some kind of cap to cover this after the floor is all done. I wonder if I use coloured aluminum to make this cap? pl300 would probably stick to it? the inspector also told me the idea is to have a thermal break to stop the floor from contacting the foundation walls so that they don't act as a heat sink. where my floor goes over the foundation at the garage doors I can put 2" foam board there as well and he told me to put two lenghts of re bar 1" in 1" down and 1" in 1" up this will apparently relieve some of the stress when driving in and out with car/or truck. As for the drain being legal he said as long as I put a T and keep it off the bottom of the drain. this way if there 's oil it won't go into the drain.

                Comment


                • #9
                  control cuts

                  another question I have is control cuts. my neightbour that likes to think he knows everything is telling me I don't need any control cuts on a 30x40' slab of concrete. on the other hand he's telling me it's going to crack because of the sm foam board underneath will overtime compress and cause cracking.

                  Comment


                  • #10
                    Re: In Floor Heating For Shop

                    You might want to post that question on the construction section.

                    I don't know about the foam collapsing causing the concrete to break but 40'x 30' is a pretty big slab.

                    Putting a control cut in isn't a big deal as long as you don't hit the radiant

                    Comment


                    • #11
                      Re: In Floor Heating For Shop

                      I am not a Masonry guy, but I have seen a lot of this. Prep work is the key to your slab. Damp compacting of your base material will help in the minimizing of cracks, reinforcing of the proper areas will also help. High density rigid foam boards 2" will be sufficient. There is a lot to know to get the job done right, my suggestion as others, find someone who is Licensed to perform this work. Unless you already have and your just trying to get smarter than them. It makes perfect sense to know whats going on, but it makes more sense to give it to the Pro's for a job done right. Yes this should be in the construction thread and not the plumbing.
                      Great Link for a Construction Owner/Tradesmen, and just say Garager sent you....

                      http://www.contractorspub.com

                      A good climbing rope will last you 3 to 5 years, a bad climbing rope will last you a life time !!!

                      Comment


                      • #12
                        Re: In Floor Heating For Shop

                        Originally posted by plumberscrack View Post
                        I think the difference in the insulation you use would be wether you are trying to keep the cold from getting up into the slab or the heat going down into the soil. The foam will keep the cold down but the foil would be better for the radiant heat.

                        Can't tell from your location just how cold it gets. Cornwall, England?
                        why can't you have both? Foil-faced stryofoam insulation is available in a number of thicknesses, placing the foil side toward the heated space to reflect the heat back in.
                        ---------------
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                        • #13
                          Re: In Floor Heating For Shop

                          from all the reading I've been doing about the foil faced.. here's some of the points I found. the foil faced performs very well on walls and ceilings or underneath a plywood floor installation where the lines are installed under floor joinsts and then foil faced placed over them. the problem apparantly with using foil under a slab is that the foil is no longer reflective once covered with dust /concrete therefore making it useless. for it to be effective it apparantly has to be very shiny.

                          Comment


                          • #14
                            Re: In Floor Heating For Shop

                            you say 6 loops .thats 6 circuits ? the pipe should be about 2 ft apart [ not 100% on that but close ]
                            make sure you do this right ,you need the right temp water or you will crack the slab .if there is not enough loops you will have cold spots .
                            I'd say this is not a job for some one to do on there own if they never did this before .you know a lot about it now so I'd have some one do it and you will know it is done right.
                            there is a lot that can go wrong
                            Charlie

                            My seek the peek fundraiser page
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                            • #15
                              Re: In Floor Heating For Shop

                              Originally posted by HVAC HAWK View Post
                              you say 6 loops .thats 6 circuits ? the pipe should be about 2 ft apart [ not 100% on that but close ]
                              make sure you do this right ,you need the right temp water or you will crack the slab .if there is not enough loops you will have cold spots .
                              I'd say this is not a job for some one to do on there own if they never did this before .you know a lot about it now so I'd have some one do it and you will know it is done right.
                              there is a lot that can go wrong
                              The concrete should be covered up for 21 days and give some extra water before you cover this up with plastic. As Hawk says, slooooowly bring the heat into the slab.
                              Great Link for a Construction Owner/Tradesmen, and just say Garager sent you....

                              http://www.contractorspub.com

                              A good climbing rope will last you 3 to 5 years, a bad climbing rope will last you a life time !!!

                              Comment

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