Ceiling isolation with radiant heat system?

Here's the next puzzle I'm thinking through. We're installing a hydronic radiant heating system which I believe requires that the plumbing/heat emission plates be installed directly to the subfloor. This is followed by an air space and foil backed insulation effectively putting the top 4" of joist space off limits. Thoughts on the idea below? I know, I know ... 3 leaves. I'm not seing any way around it though. Thanks again!

leecow wrote:

Here's the next puzzle I'm thinking through. We're installing a hydronic radiant heating system which I believe requires that the plumbing/heat emission plates be installed directly to the subfloor. This is followed by an air space and foil backed insulation effectively putting the top 4" of joist space off limits. Thoughts on the idea below? I know, I know ... 3 leaves. I'm not seing any way around it though. Thanks again!

Lee, there is another way of doing this - it's usually intended for retro-fits - where you don't want to rip down the ceiling below - but you can take the pipe and run it on top of your decking instead of below. This is set into a series of particle board slabs - with chamfered edges -- and then the final assembly is caulked into place. In this manner it becomes a part of the leaf assembly ands doesn't cause the problem with the 3rd leaf. here's a link with the idea shown: http://www.wirsbo.ca/default.php?id=31 Here's another manufacturer with a slightly different approach - http://www.warmzone.com/hydronic-radiant-floor-heat.asp In either case - it's more heat - faster - with less energy loss than the under floor installation. BTW - I've used this in the construction of world class studios (although then it was slab-sets). Sincerely, Rod

Great option Rod. Unfortunately the room above is part of the existing house that is not being remodelled. Floors will be refinished but they're not coming out for replacement. Any mitigation options available within my installation constaints?

leecow wrote:

Great option Rod. Unfortunately the room above is part of the existing house that is not being remodelled. Floors will be refinished but they're not coming out for replacement. Any mitigation options available within my installation constaints?

Nope - this now becomes one of those situations where I explain to people that what they have to live with - just live with. If 3 leaves it is - then it is....... Make up for it with additioanl mass on the bottom most leaf and live with what you have when you're done. Green Glue will help.......... Rod

Yep, that's where I figured this was heading :wink: . Green Glue is definitely in the recipe. Will running 3 GB layers on both bottom and middle leaves net benefits beyond just the bottom leaf? Assuming the joists are hemlock rather than doug fir, load capacity is good for 65psf with current dead load sitting at about 10 psf. Thanks again for the invaluable help here and in your book.

Upper leaf, yes - lower leaf, I'd have to first ask what the span/centers for those 2x6's is - unless it's a very narrow room, I doubt you have 65 PSF left over :wink: Keep in mind that a third layer in BOTH locations is only a 50% increase in mass, so won't buy you 6 dB under the BEST of circumstances; maybe about 4, not sure. I've no good feel for 3-leaf stuff yet, just that it's not as good at LF as 2-leaf... Steve

Thanks for the feed back Steve. There are enough things in the way that the 'floated' ceiling is not going to be practical. I'm leaning toward something like: 1) 2 layers of GB below the radiant system with Green Glue 2) Iso box the plumbing that's in the way ala Rod's figure 10.14 working around the ducting. 3) RC2, 2 layers of GB with Green Glue Trusting in GGs test data showing that the GB/GG/GB setup performs on par with 4 layers of GB.

You forgot insulation; also, if you can afford it I'd recommend using RSIC clips and channel over the RC... Steve

Yep, insulation generously stuffed into the space. I'm a bunch shy on headroom (7'6" from concrete to joist) and will need to determine if RISC clips will work. The Kinetics ISOMAX is the lowest profile I've run across and may work in my installation. Still looking for specs on the various RISC setups that have the rubber 'puck' to determine if they're an option.