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Radiant Ceiling between joists?

aschwa
aschwa Member Posts: 24
Hi all-

I'm interested in doing a hydronic radiant retrofit on my ground floor. I don't want to lose any ceiling height, and I have a slab foundation.

Any way to do this? Baseboard radiators (anything visible whatsoever) is not an option.

For instance, is it possible to install hydronic radiant ceilings by installing the tubing between the joists and therefore not have to lower the ceilings?

Thanks,

Andrew

Comments

  • Rich_49
    Rich_49 Member Posts: 2,703
    edited September 2015
    Did this type of install 4 years go in an 1870's home . Original ceilings and woodwork had to remain . Carefully cut / ground all plaster oozing through the lath , installed Uponor joist Trak plates 8" on center over aluminum flashing , secured using peanut screws , 3" spray foam directly over the installation . 10' ceilings and the place stays nice and warm .

    Time consuming but worth it to keep all the original stuff looking good
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    SWEI
  • ChrisJ
    ChrisJ Member Posts: 13,883
    Rich said:

    Did this type of install 4 years go in an 1870's home . Original ceilings and woodwork had to remain . Carefully cut / ground all plaster oozing through the lath , installed Uponor joist Trak plates 8" on center over aluminum flashing , secured using peanut screws , 3" spray foam directly over the installation . 10' ceilings and the place stays nice and warm .

    Time consuming but worth it to keep all the original stuff looking good

    Rich,
    I'm not following.
    You cut and ground the keyways off of the plaster?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Zman
    Zman Member Posts: 7,434
    If you could afford just 3/4", this one would save a whole lot of labor.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    Rich_49BobbyBoy
  • Rich_49
    Rich_49 Member Posts: 2,703
    edited September 2015
    Leveled them out or made them uniform would have been more accurate Chris . Probably could have gone farther due to the coffered ceilings below .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • ChrisJ
    ChrisJ Member Posts: 13,883
    Rich said:

    Leveled them out or made them uniform would have been more accurate Chris . Probably could have gone farther due to the coffered ceilings below .

    Scary work and very risky. One wrong move and................
    ;)
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Rich_49
    Rich_49 Member Posts: 2,703
    We did make it through . Deep Energy retrofit on a 142 year old house is an experience to say the least . Radiant ceilings , walls , some QuikTrak , Joist Trak below sub floor , embedded , overpour . Like a showplace for many different types of radiant . Happy to say all if it works very well today .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    ChrisJ
  • SWEI
    SWEI Member Posts: 7,356
    We just love projects like this. Really rewarding when you make it work and keep the original finishes.
  • aschwa
    aschwa Member Posts: 24
    I'm not completely following. I don't have coffered ceilings. In that case, your solution wouldn't work, right Rich?
  • Gordy
    Gordy Member Posts: 9,537
    edited September 2015
    Rich is referring to old plaster with wooden lath. The brown coat is burned in so the plaster ozes through the gaps in the wood lath. This keyed bond holds the plaster to the lath. Now what is your ceiling detail?
  • aschwa
    aschwa Member Posts: 24
    Haven't opened up the ceilings yet, but here's what we expect:
    joists are 2x12 for most rooms, 16" center-to-center

    8 foot ceilings, drywall covering the joists.

    Does that answer your question?
  • Rich_49
    Rich_49 Member Posts: 2,703
    Drywall makes it an easy retrofit . Nice and flat between the joists or at least it should be . Will you be removing the drywall from below ? If so you could look into Sunboard's Sunfoam panels , they fasten right to the bottom of the joists and tubing goes right in , Drywall contractor can see the tubes so there is no reason for him to nail into them . R13 in the cavities plus the board is all you'll need . You'll really need to perform a heat loss to determine water temp , BTU / sf requirement and all that no matter what you do .

    http://www.sunboardpanel.com/Products.html
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    BobbyBoy
  • aschwa
    aschwa Member Posts: 24
    Those ceilings will be open from both above and below. I'll be installing radiant floors on the second floor throughout the house, so the joists will be accessible from above as well.

    Rich, would your Sunboard solution involve me losing a bit of ceiling height?
  • Rich_49
    Rich_49 Member Posts: 2,703
    Yes, any radiant ceiling would . Unless you utilize a detail similar to what I described above . XLath , Sunboard , Joist Trak with strips , all will lower finish ceiling height . But ceilings don't require cutting doors and much other necessary stuff . 1 1/2" on the ceiling hurts alot less than an 1 1/2 on the floor
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    Zman
  • aschwa
    aschwa Member Posts: 24
    I read in a couple of places that radiant ceilings over a slab floor are a bad idea. (For instance, see here)

    Why is that? Do you agree?

    We're in the SF Bay area.
  • SWEI
    SWEI Member Posts: 7,356
    That summary is good, so yes -- I would agree.

    More importantly for a retrofit, radiant floor heat in an uninsulated slab is kind of a deal-killer. More so in a really cold climate, but still not a good thing even in the mild climate of the SFBA.

    Ceilings...
    Zman
  • aschwa
    aschwa Member Posts: 24
    If I'd need to raise the floors if I insulate my slab anyway, then I might as well do radiant floors instead of radiant ceilings. Sound right?
  • SWEI
    SWEI Member Posts: 7,356
    Why do you need to insulate the slab? Are you planning on carpet, hardwood, or something else?
  • aschwa
    aschwa Member Posts: 24
    California Energy Code says that heated slabs must be insulated.

    Hardwood floors.
  • SWEI
    SWEI Member Posts: 7,356
    aschwa said:

    If I'd need to raise the floors if I insulate my slab anyway, then I might as well do radiant floors instead of radiant ceilings. Sound right?

    Your logic escapes me. We suggested heating the ceilings. You said you were insulating the slab anyway.
    ERF
  • aschwa
    aschwa Member Posts: 24
    Sorry. I misunderstood your question. Let me clarify.

    My understanding from you is that heating the ceilings will require raising the floors in order to insulate the slab.

    The point I was making is: If I'm raising the floors anyway, then I might as well raise them some more and do radiant floors instead of radiant ceilings.

    Does that make more sense?
  • aschwa
    aschwa Member Posts: 24
    In other words, my options are radiant ceilings with raised floors or radiant floors with raised floors.

    Either way, my floors would have to be raised.
  • SWEI
    SWEI Member Posts: 7,356
    If you heat the ceilings and install carpet with even a small R-value, I would not bother insulating the floors in that climate. If you're doing laminate floors, most of those have a bit of rubber/foam underneath that provides at least some amount of thermal isolation.

    Are you on NG or LPG there? Possible modifications to the above advice depending on fuel costs.
    RobG
  • aschwa
    aschwa Member Posts: 24
    How about hardwood?

    We're on nat gas.
  • Rich_49
    Rich_49 Member Posts: 2,703
    Aschwa ,

    California is not the only one that requires heated slabs to be insulated . Long before there was a California Mother Nature required this to work also . It's the alw , the laws of physics . I do not completely agree with the paper you referenced . At this point in time , most states are adopting and beginning to enforce IECC 2012 -2015 , whichever they are looking at and how far behind the times they are . These codes require slab insulation PERIOD . Heated or not . Believe it or not a cold slab will suck heat away from the interior space even in a forced air house , HOT goes to COLD . You could add perimeter insulation outside and down 2 feet and call it a day .

    What would your assembly detail for hardwood on top of a slab look like ?
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • SWEI
    SWEI Member Posts: 7,356
    Thought this was a retrofit?
  • aschwa
    aschwa Member Posts: 24
    It is. Whole house remodel.
  • Gordy
    Gordy Member Posts: 9,537
    As @SWEI said do the radiant ceiling use what ever floor coverings call it a day. As mentioned before raising the floor detail involves more work than lowering the ceiling detail. The uninsulated slab is not as SWEI stated in your climate going to be a deal breaker.

    How ever for those that happen to come across this thread later. In a more severe winter climate I would recommend insulating the slab at the very least the perimeter. Radiant floor, or ceiling. As Rich said it will suck the heat energy out of an envelope.

    Radiant heat will work even in an uninsulated slab the cost is considerable energy consumption which is why we insulate for the environment, and the wallet so ROI is narrowed to an exceptable time table.

    As an owner of radiant ceilings, and floors I can testify that you won't be sorry. I always enjoyed Tom Tesmar when he frequented the RPA web site.
  • aschwa
    aschwa Member Posts: 24
    Here's what I'm thinking based on this forum's input:
    - Radiant ceilings on the first floor over an uninsulated slab. I'll use xLath and the 8' ceilings will drop 3/4".
    - Radiant floors on the second floor. Probably go with gypcrete.

    Does this sound right?
  • hot_rod
    hot_rod Member Posts: 18,208
    Sounds good. I think several million Californians live on un-insulated concrete slabs, cover it as Kurt mentioned with some minimal r-value covering and move on.

    I like gyp applications for a nice consistent floor surface temperature. I'd call them a medium mass system. They add great sound and fire barrier to the structure also, and is a nice leveling feature. Gyp was originally designed for hotel floors for those reasons.

    Make sure to accommodate the stair riser calculation if you add that 1-1/2" to the upper floor.

    Gyp does add some dead weight to the floors, are they solid now? If they bounce as you walk across them from undersized joists, the gyp will add even more load.

    Seal each and every hole in the floor before you pour gyp or it will end up downstairs!
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Zman
  • aschwa
    aschwa Member Posts: 24
    There's actually existing concrete (not gypcrete) from a 1960s era hydronic floor system on the second floor that was deactivated ~15 years ago. The concrete will be demolished and the weight of the gypcrete will be less than the existing concrete, so I think I'm good there.
  • Tom_133
    Tom_133 Member Posts: 839
    Aschwa,

    Are your bedrooms on the gypcrete or are they downstairs? If they are upstairs they should be zoned so they can be at a lower room temp. I have run into a lot of people who after the concrete or Gypcrete was poured found the slow temperature swings did not allow them to be comfortable in bedrooms. If you have them zoned separately, or just the bedrooms on their own zone than you should be fine, just a word of caution. I'm sure you already thought of it.
    Tom
    Montpelier Vt
  • aschwa
    aschwa Member Posts: 24
    They are indeed upstairs on the gypcrete. I will make sure to zone them separately.

    Your post seems to imply that if the bedrooms were on the first floor with the radiant ceilings, then you wouldn't be worried. Why is that?
  • hot_rod
    hot_rod Member Posts: 18,208
    I'm not a huge fan of radiant floors in bedrooms.

    Once the bed and furnishings are loaded in there is often not much "available floor space" left to cover the load. Any furniture that goes down to the floor or has a skirting like some beds, limits radiant floor considerably.

    Fast responding panel rads ar my favorite for bedrooms. They are often the least destructive heat emitter to add in a reno project. A TRV or setback type TRV is an ideal control.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    GordyRich_49SWEI
  • aschwa
    aschwa Member Posts: 24
    edited October 2015
    @hot rod : You prefer panel radiators over ceiling radiators for bedrooms?
  • Gordy
    Gordy Member Posts: 9,537
    @aschwa since it has not been mentioned. Do understand that you need to insulate the ceiling radiant detail from the floor radiant detail above.
  • aschwa
    aschwa Member Posts: 24
    Yes absolutely
  • hot_rod
    hot_rod Member Posts: 18,208
    aschwa said:

    @hot rod : You prefer panel radiators over ceiling radiators for bedrooms?

    I like panel rads because they are low mass, low water content. As such they warm up within minutes, and ramp down quickly. They also tuck in against the wall nicely maybe 3" total off the wall, not as imposing in the room.

    A wide range of sizes, shapes, colors are available.

    Now for a historic home, or if you like the looks of cast iron radiators, it's in the eye of the beholder.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream