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Hardwood floor over concrete

Do-It-All Member Posts: 4
It depends on the hardwood to some extent.

I'm primarily a GC building large custom homes (8,000+ ft.) but also do our own radiant installs.

If you are installing 'normal' width hardwood (3-4" wide), then you can use sleepers but you have to be very careful about the lengths of your hardwood to ensure that every joint falls on a sleeper. We always seal our sleepers with urethane on all sides before installing them to eliminate moisture issues from the gypcrete.

If you are installing wide-plank (we've done 12"+ from reclaimed hard and softwood), we'll install sleepers and then 3/4" ply on top of that and then nail to the plywood.

Your heating calcs then have to adjust for the extra plywood on top and always keeping in mind that you don't want the underside of the hardwood to cook. We always put a few slab sensors in the gypcrete so we can keep an eye on things,


  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Looking at a job

    that wants a radiant floor. The pre-existing floor is a step down floor onto a slab. We were going to build up with 2 in blue styrofoam and staple tubing to it and then pour over top with a new 2" slab. The HO wants a hardwood floor to match the rest of the house. All of a sudden it's more complicated. How do you guys install hardwood over concrete. Do you build in sleepers, or do you go with the engineered hardwood floors? Also I've heard any space between the concrete and the hardwood creates a loss in capacity. Thanks for any input. WW

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  • hot_rod
    hot_rod Member Posts: 22,103
    Check out

    the hardwood that www.launstein.com offers. It is solid wood, 3/8" thickness that has a locking detail.

    Consider this or engineered hardwood over the Roth panels.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Home Depot Employee
    Home Depot Employee Member Posts: 329

    I agree with Hot Rod, the Roth or Rahau System is slick for this app.
  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    Roth on Cocrete


    We've used Roth several times with concrete slabs. You must have a good level slab - no valleys or peaks. You may need to use some flash patch in areas to level it out if its an old slab.

    The older floors tend to have areas that have sunken in a bit when the slab settled. If you don't address this condition, it could be noticeable when your floor is laid - especially when the room is empty with no furniture.

    In this job (see attachments) we cut the panels down from their normal 2x4 size. This wood contractor did not want to nail his wood at 24" spacing.

    We used mushroom spikes and PL adhesive to fasten the panels to the floor. No issues other than a few SDS hammerdrill bits for the spikes.

    If you are going to use engineered hardwoods, you won't need the sleepers as the floor will float on the thin layer of foam across the top of the panels.

    Primary advantage of this product - it's low mass. You will have quick response times, heating up, and cooling down. Your not heating up a few thousand pounds of concrete each cycle. Nice with constant circulation radiant.

    I'm not clear on your comment " I've heard any space between the concrete and the hardwood creates a loss in capacity " . Based on this method, the wood, real or engineered, is right on top of the aluminum transfer surface so you can utilize lower supply temps than with a product like Wirsbo Quik-Trak or Viega Climate Panel. The Viega and Wirsbo product use a 5/16" pex, so loop lengths tend to be limited.

    These panels come in kits - 10 2x4 panels, and an assortment of returns and straight transition pieces. Each kit covers 96 sqft of floor. The come in 3/4" thick - 3/8" pex and 1" thick - 1/2" pex.

    Level floor - no issues. If you want more photos, email me, I will send them to you.

    Hope this gives you an option you can consider.


  • 2" overpour?

    Sleepers are fine and not that hard. Use gypcrete, apparently it doesn't shrink much.

    Keep your tubing on centers fairly tight though so you don't get heat striping.

    Floating wood is definitely easiest, but sleepers have been used for years in thin pour applications.

    The panel products mentioned below are good too, but probably a bit more expensive and definitely more work for you (though one less contractor if you get gyp).
  • lee_7
    lee_7 Member Posts: 458

    Look into Viega's products. They have climate panel system that would work great. All you need is a barrier over concrete, 3/4" plywood secured to concrete, Nail down this panels to floor and then snap pipe into grooves in panels. Then run hardwood floor perpendicular to tubing so you can see tubes when nailing down floor.
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    I've never seen

    the Roth panels. Who sells them? How do they compare in price to other top side panels. I've been using quik trak a long time now, but they are expensive and time comsuming to put in. WW

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  • Richard_6
    Richard_6 Member Posts: 22
    we do...

    this quite often with Crete-Heat and Level Rock by USG other similar type lightweight concrete or gyp-crete work well also. This cuts down install time dramatically. We have done both floating engineered and glue down hard wood. Depends on the look the customer wants.
  • Rich Kontny_3
    Rich Kontny_3 Member Posts: 562
    Home Depot Employee


    As long as you are contributing I would like to know why HD got out of the wholesale end of things after such a short time. I suspect that the delays in payments inherant to contracting conflicted with their C.O.D. payment structure at their regular consumer outlets????

    Just curious.

    Rich Kontny

    Make Peace our Passion while Supporting our Troops!
  • Richard_6
    Richard_6 Member Posts: 22

    Here is a picture of a job we just finished. This is a glue down, engineered cherry over Crete-Heat and Level Rock.
  • TAG
    TAG Member Posts: 755

    I have been reading for a while -- I have been given some great ideas for my (about to start ) second home project - Thanks

    I retrofited the house I live in now with radiant 13 years ago -- I needed to go with Buderus panels/ plates under harwood/ new mud with tile/ overpour (to level a slab) with tile/rugs - you get the idea.

    I just built a bump out to a room 15x20 -- I did not want to have a crawl space or the $$ of a full basement. I went with warmboard (found from reading this site) over a slab. Insulation/ vapor/ slab/ vapor/ 2x4 sleepers w/insulation between/ 3/4 oak.

    I can not say enough about this product -- it is down .. it is done. No add this/ glue that/ and no problems finding a place to nail! It does have a learning curve -- I am good at it now that it is done.

    Living in my house I have learned a few things about radiant -- response time is very important. The areas of the house with the heavy AL panels under the floor are quick -- the overpour in a large room (30x20 with two loops) is not.
    In New Jersey this is important. I have seen the same problem with the lightweight floors. I would pick my product based on location in the USA.

    All I can say is that it provided a very solid floor -- without a thickness problem. It has not been cold enough to test the product, but the thickness of the AL sitting ontop over the whole surface should work just as well as the panels under the subfloor in the other parts of the house

  • I love warmboard, nothing to take from it, but there is no reason to live with a system that is not performing the way you want.

    Response time shouldn't be an issue. Proper control renders it moot in the vast majority of homes.
  • TAG
    TAG Member Posts: 755

    The weather today in NJ is a perfect example -- first chilly morning. My system is off by the way -- but the only time the system would be needed on a morning like this is for a few hours at best -- even when people are in the house all day.

    I find that the slab areas tend to require more time to heat up and longer to cool off -- no surprise to anyone. On days when it is very cold out this is not an issue -- unless we have large sun gain. My house has a buderus gas boiler with the logmatic control -- and actually more controls then needed as this was my first system. If the heat requirements change faster than the slab can - no amount of controls can cool the slab.

    In my shore house that I use throughout the year, I installed a heat pump. This morning I would have turned it on for 15 min.

    All I am saying is that different types of systems work a little better in different parts of the world. And quick response is a key in many areas as the seasons change

  • If the heat requirements change faster than the slab CAN, you're right.

    However, that's pretty rare. Most often, the problem is the slab doesn't "know" the requirements have changed until it is too late: edit to add: that is, the system waits until it hits room temp or gets too cold to start reacting. A smart system can start reacting earlier, by looking at the change of temperature's direction and speed, not just the current setpoint.

    Systems with floor sensing and indoor feedback can handle any constant heat situation except for very rapid heat gain from (edit) low mass sources (woodstove). And very rapid gain will in most cases result in an overheated space with or without mass radiant, as most very rapid gains are not tied to a room setpoint, they are uncontrolled "heat dumps" of sun or stove.

    Beyond that one type of issue, I have never run into a high mass radiant system I could not maintain at a comfortable temperature with proper control, and I design radiant systems in all climate zones. In very extremely mild climates with lots of glass, you might have problems. Beyond that, it can be dealt with; it just takes more than a round thermostat and a fixed water temperature.
  • Wild Rover
    Wild Rover Member Posts: 41
    Glenn Sossin-more pictures

    Glenn, I think i might use the roth panels on my upcoming project and was wondering if you could send some more pictures to help with my install. Also was wondering what size tubing was used in the 1st picture you posted and what size lumber was used. Was this 1x stock or strapping?

  • Home Depot Employee
    Home Depot Employee Member Posts: 329
    All I know


    Sorry for the late reply, took a quick trip to Orlando.
    This is from my inside knowledge of being a past wholesaler principal (Not and never was HD).

    Hughes Supply among the few others were weak inside with minimal succesion plans in place. At that time Ex-CEO Mr. Dinardo of HD was bored and needed a pet project and convinced the board with a few on it that this would be their next step in conquering the building supplies world.

    Well understanding true value of a company and buying right along with being prepared to hold on to it long enough for the construction industry in their served areas to return to a stronger economic environment is key.

    That along with the gutting and leaving of all the existing supply house personel changes the distributor attitude and the decline starts from there. You can only battle with price for so long. More importantly, contractors buy from who they like, know and trust.

    So in the end the company sells for less than it was bought for, most branches will never recover and Mr. Dinardo walks away with 200 Million. Course thats not all, now people seem to think he can save Chrysler.

    Its a wonderfull country, take Kodak for instance. The last 5 CEO's left the company in worse shape than when they started yet, all of them got huge departing cash contributions.

    For those few, way better then winning the powerball
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