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Thread: 2500 sq foot of concrete slab

  1. #1

    Default 2500 sq foot of concrete slab

    In my walk out basement entertainment area. The area has heat/air but the floor is coooold. Any solutiond to cover it, there's carpet, eng hardwoods, what else?

    John
    Last edited by John_NC; 12-20-2006 at 08:14 AM.

  2. #2
    Homeowner geniescience's Avatar
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    Default warm tiles

    john

    ASHRAE standards agree with you. Temperature difference in the room ought not be more than a degree from floor to chest height.

    big job, in terms of time. Rip everything out. Put foam on floor slab to separate cold concrete below from what is above it. Put electric heat cables on top. Tile on that. Floor always warm.

    The thinnest and best foam treated to accept tile on top is Wedi. 1/4", 1/2". 1" etc. The best heat cable company is Warmly Yours, in terms of being able to explain things to the general public and to provide service. Other companies can create problems or confusion. Always go back to Warmly Yours for answers.

    second option : put a sound insulation membrane under wood floor. The kind of synthetic "felt" that goes under engineered hardwood. Or put foam underneath. then heat cables, then wood floor.

    third option: put any membrane, anything, on the floor under whatever you put on top.

    david

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Default heat

    Two things to consider.
    1. Radiant heat is a comfortable heat, but it is also an expensive way to heat.
    2. Electric radiant heat is also the most expensive way to keep warm, especially since you won't have an area that can be turned off when it is not in use. (It would take too long to reheat it if you did).

  4. #4
    Homeowner geniescience's Avatar
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    Default

    uh-oh, we are going to disagree here.
    Quote Originally Posted by hj
    Two things to consider.
    1. Radiant heat is a comfortable heat, but it is also an expensive way to heat.
    2. Electric radiant heat is also the most expensive way to keep warm, especially since you won't have an area that can be turned off when it is not in use. (It would take too long to reheat it if you did).
    1. it is NOT expensive. Check it out fully. Define cost. We may be able to agree on power consumed (watts) and cost per watt.
    2. true that you will probably create a single zone, and keep it warm all the time.

    david

  5. #5

    Default Never post on Ambien!

    Already correctd the spelling in my orig post but meant to ask. What other options to hardwood or carpet to keep from freezing your feet in the winter on a concrete slab.

    This is new construction. I already double insulated the exterior daylight walls.

    1" rigid foam against the forms when poured and another layer just inside the wall base in an "L" shape extending 2-3' under the slab.

    Carpet would work but I'm not a fan of carpet in a basement in case of water. Hardwood would work but again, I'm not a fan of that solution for the whole space either.

    Tile would be the best option and the Wedi insulating underlayment is the kind of solution I was looking for but damn, $2.66 a square foot + labor & materials to install. I found a cork underlayment that's a bit less expensive here.

    The idel solution would be insulative thinset at a resonable cost. Is ther such a thing?

    Heating the floor as an option went out the window when my hot water radiant heating dream died. Electric radiant, maybe for a bathroom but 2500 sq foot, fagaddaboudit.

    It's looking like a combination of carpet/eng hardwood and shoes!

    John
    Last edited by John_NC; 12-20-2006 at 08:49 AM.

  6. #6
    Rancher
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    Default

    Quote Originally Posted by John_NC
    Heating the floor as an option went out the window when my hot water radiant heating dream died. Electric radiant, maybe for a bathroom but 2500 sq foot,
    Why did your hydronic floor heating go bye bye, you'll regret that decision.

  7. #7
    Homeowner geniescience's Avatar
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    Default cork is good. Very good.

    cork designed to be a membrane under tiles is very good, and cheaper than Wedi. I have used both, cork and Wedi. Both are good at heat insulation. Very good.

    Electric cables could be good. How about just a few sq feet near the outside walls and doors? That will lower cost by 80%.

    david

  8. #8

    Default Radiant heat in the slab

    Would have loved it, cost was too much, tight budget.

    I did splurge on the insulation though, did spray foam type.

    John

  9. #9

    Default

    Even against advice of others...after all of my reading... I wouldn't build a new house without radiant floor heat even if it meant letting something else suffer. That's some good stuff.

  10. #10

    Default

    I have used electric in floor heat by "Warmly Yours".

    In my case I used "Wedi" board, which is an insulated board available in various thicknesses. On top of that I placed the electric heat elements in a leveling compound. In my cases I used tile above that, but you could also use carpet.

    If used with a floor sensing thermostat, the cost of operation is kept rather low. Our tile takes less than an hour to heat up. Very pleased with the results.

  11. #11
    In the Trades Bob NH's Avatar
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    Default

    First, decide how much thickness you want to dedicate to the floor.

    If it is susceptible to water infiltration, then assume it will get wet. If not, then you need at least a membrane to keep soil moisture from getting through the concrete.

    Some closed cell foam insulation insulation will keep the heat loss down and it can be strong and water resistant. You can get quite rigid foam or you can put a hard surface on it. Then you can cover it with carpet consistent with the location.

    What makes floors cold is the heat transfer from your feet. A tile floor feels colder than a carpet floor at the same temperature because the carpet won't transfer heat as quickly.

    I don't like in-floor heating on concrete unless you have very good insulation under the concrete. You can lose half the heat to the earth.

  12. #12
    Homeowner geniescience's Avatar
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    Default Way more than half, if heat cables put on slab naked

    Heat loss is far more than half, when the slab is not separated by some form of themal break. Here is how this occurs. In the first little time interval when you turn the power on, half goes up, half goes down. So at that point you are sending half of your power into the slab. Then, once the tile layer gains some heat, it itself becomes a heat source when compared to the slab, which has not warmed up as much. So the thin layer of tile becomes a bit of a radiator, losing some of its heat to the slab, which keeps on sucking heat permanantly since it is connected to the earth below, and it will always be losing heat to the ground while gaining heat from above. A permanent heat flow, just like a small electric current, a leakage current. So insulation is needed, to slow down the heat transfer process, so that a far far larger portion of energy (heat) is kept in the house. A slab is a heat sink, and a slab on grade is an even greater heat sink than a slab above ground in a concrete building. A heat sink has a big impact when it is in direct contact with warmth.
    Quote Originally Posted by Bob NH
    ...at least a membrane to keep soil moisture from getting through the concrete <....> lose half the heat to the earth.
    p.s. this may be a minor thing, but i figure it's the right place here to mention it.
    p.p.s. cork is a good thermal break and it is used under tiles everywhere in the world.

  13. #13

    Default

    I recall reading alot about the cork. It appears to be really good. Also, a properly installed hydronic heated floor, the slab is not just a heat sink, it is a heat bank as well. Where some people mess up is they don't realize that heat is much like electricity or water... it flows and will run right out the components of the building if there is not something there to stop it (insulation).

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