I've done some searches on this forum on this question and it seems nobody has addressed the situation I have going on.
My studio is a 30x30 space above a heated garage. The garage portion below the studio is wired to potentially have tracking done in it, but I am mainly a post facility. I will be doing mostly VOs and post mixes (my clients are ESPN, VS. Fine Living, Fox Sports). Right now the work I do is either at a production house or in my den. The birth of my son has forced me to finish the studio, a project I started when I built the house 4 years ago, but never finished.
The upstairs of the space (which is only connected to the house via a 1 story 9x9 breezeway) will have 3 rooms: control room (18x22) VO (8x5) and VO/instrument (9x9).
I have major flanking concerns with the floor. I do want to contain as much sound as possible in the studio, and I want to have the instrument rooms isolated from the control room. The floor right now is 3/4 CDX with staple up radiant heat under it. Luckily the studio has a very large AC unit properly installed and ducted that I will also be using for heat with a heat coil. The radiant heat will have a separate thermostat from the forced air unit and will keep the upstairs of the studio at 60 all winter regardless if I am using the space or not.
So, obviously I am not a candidate for a floating floor, but what do I do? I could use some sort of iso clips on top of the CDX, and float another CDX subfloor, but then I would have a triple leaf to the garage. Another option is Green Glue. I called them and they said it would work fine with radiant heat. They suggested CDX/greenglue/3/4OSB or 1/2 Cement board. This is a possibility. The most interesting option is a 1 inch layer of self leveling quick-crete. The green glue company says sound board works very well on floor with green glue, but Homosote 440 does have some insulating properties. While I am OK with slowing down the rate of heat transfer from the radiant to the room, I do not want to have a radiant heat system insulated from below AND above, that would be bad.
Would CDX/greenglue/OSB be better than: CDX/greenglue/quickcrete? would a quickcrete green glue sandwich even work? I like the idea of the self leveling cement since it a great thermal mass.
Any other ideas are very welcome.
BTW, I have Rod's book and have gone through his floor section. This is where I found the idea for the quickcrete.
Need suggestions on isolating floor with radiant heat
Originally posted at johnlsayers.com, topic 10272.
do you need a high level of isolation in each room, or maybe just the instrument booth? depending on the floor construction, would determine how much weight you can support for the cement options...
Everything begins with determining exactly how your radiant system was designed.
If it was designed for just carpet and pad over the sub floor - then it will never produce enough radiation to overcome what you are considering placing over the existing subfloor.
These systems are not designed helter skelter - but are calculated very carefully to apply just the right amount of radiation (taking finished flooring and additional possible sub-floors into consideration as a part of the design) - and you can totally destroy the system by ignoring that.
It might be easier to just abandon it (the PEX tubing) in place...........
Rod
Rod,
I called my plumber earlier today and we talked about just those questions you asked. He told me the system was deigned to keep the room at 68 degrees with wood 3/4" flooring added over the subfloor. I told him about the issue I was going to have with adding extra layers of subfloor and his opinion on the matter was similar to yours but a bit different.
Obviously you are correct that adding mass would throw off the system very much. He said it would be impossible to tell how much now that I have super insulated the structure. His opinion was that if I did add another 3/4 sub floor it would double the time it would take for the system to be able to react. He thought this was not a problem, just an inconvenience. When I asked him about a third layer he told me he didn't think the system could get the room to 70 degrees within a 4 hour period, and possible would not be able to get it to 70 on a really cold day at all.
He did say that there was no way I could damage the system, just my propane bill (and thus my wallet). If it takes too long for the heat to transfer then I would be just wasting money (and energy).
Now, we did talk about using the radiant heat as just a backup heat source for when the room is not used. If I did that, and set my radiant heat thermostat to say 58 degrees it would still serve a purpose. He pointed out that the closer I put the thermostat to the floor the better it would work in this case.
So I guess what I have to find out is:
Can my structure support a cement overlay?
Would it be worth it to re-route the pex to above my current sub-floor and encase it in cement. This would not be too hard, the manifold is accessible just expensive.
Can I live with one layer or maybe 2 layers of extra sub-floor.
The worst case scenario is such: I put too much extra mass on the floor and the sytem just runs 24/7. I don't have any zone that does that now. To be honest we have 6 zones of radiant in our house and they all work beautifully. All the zones take about 45mins to 1 hour to raise the ambient room temperature 3 degrees. This speaks to how well the system was designed, and to how well stiff poly-iso insulation works (though it sucks for sound).
Rod, is the Gyp-Crete you talk about in your book heavier than OSB? Sheetrock? If I was to add one more layer which one would it be?
I do not need a high level of iso in the control room. Just in the instrument rooms (which buffer me from the house). I am worried about the floor flanking to the exterior structure, and then into the main portion of the house. Do you have an idea for just the iso rooms?do you need a high level of isolation in each room, or maybe just the instrument booth? depending on the floor construction, would determine how much weight you can support for the cement options...
Sorry - I di n't mean to suggest that it could blow up - but rather - if I take a pile of money and dump it down a pipe into a heater - and I don't get any money out of the heater - and this is because I buried the heater below more material than it was capable of heating throught - then (IMHO anyway) I just destroyed the system.He did say that there was no way I could damage the system, just my propane bill (and thus my wallet). If it takes too long for the heat to transfer then I would be just wasting money (and energy).
It doesn't make any sense to me- what makes these systems so great is that they are low temp and extremely high efficiency.......... take away that efficiency and you might as well just change the supply / returns over to the PEX style baseboard heaters - and now at least you're getting the heat.......Now, we did talk about using the radiant heat as just a backup heat source for when the room is not used. If I did that, and set my radiant heat thermostat to say 58 degrees it would still serve a purpose. He pointed out that the closer I put the thermostat to the floor the better it would work in this case.
Contact a local structural engineer - and let him determine exactly how much additional load (if any) your deck can handle. Would it be worth it to re-route the pex to above my current sub-floor and encase it in cement. This would not be too hard, the manifold is accessible just expensive. It would from my point of view......So I guess what I have to find out is: Can my structure support a cement overlay?
There is no way for me -fix it to work with what you want to do.Can I live with one layer or maybe 2 layers of extra sub-floor. The worst case scenario is such: I put too much extra mass on the floor and the sytem just runs 24/7. I don't have any zone that does that now. To be honest we have 6 zones of radiant in our house and they all work beautifully. All the zones take about 45mins to 1 hour to raise the ambient room temperature 3 degrees. This speaks to how well the system was designed, and to how well stiff poly-iso insulation works (though it sucks for sound).
A 3/4 sheet of OSB (32 sf) runs about 70 to 80 pounds...... a sheet (32 sf) of 5/8" gyp is about 2.6 psf - or about 83 psf - and Gyp-Crete weighs in around 6.5 psf or 192 pounds per 32 sf. I hope some of this helped........Rod, is the Gyp-Crete you talk about in your book heavier than OSB? Sheetrock? If I was to add one more layer which one would it be?
Agreed!Sorry - I didn't mean to suggest that it could blow up - but rather - if I take a pile of money and dump it down a pipe into a heater - and I don't get any money out of the heater - and this is because I buried the heater below more material than it was capable of heating throught - then (IMHO anyway) I just destroyed the system.
Very interesting idea, I had not thought of that! I didn't realize they sold pex baseborad radiators. I'll look into that for sure.It doesn't make any sense to me- what makes these systems so great is that they are low temp and extremely high efficiency.......... take away that efficiency and you might as well just change the supply / returns over to the PEX style baseboard heaters - and now at least you're getting the heat.......
I will, especially after all of the info you gave me in the wall/homo posting.Contact a local structural engineer - and let him determine exactly how much additional load (if any) your deck can handle.
Yeah, I agree now, my only concern is cost. Is the Gyp-crete expensive? is it something I can do myself? seems like the best solution for the heat. I can run the tubes myself (did it in all the other 5 zones in the house). That just takes time. The gyp-crete and getting my plumber back in to re plumb the manifold might blow me out of the water. Would I be served with green glue under the gyp-crete?Would it be worth it to re-route the pex to above my current sub-floor and encase it in cement. This would not be too hard, the manifold is accessible just expensive. It would from my point of view......
Tremendously helpful. I can't thank you enough. I'll see what I can do to make your book a required text book over at the University of Hartford. :DA 3/4 sheet of OSB (32 sf) runs about 70 to 80 pounds...... a sheet (32 sf) of 5/8" gyp is about 2.6 psf - or about 83 psf - and Gyp-Crete weighs in around 6.5 psf or 192 pounds per 32 sf. I hope some of this helped........
I just wanted to update this thread in case someone was researching.
My plumber assured me that the extra mass I was thinking of (adding 1/2" MDF and GG, this was all I had budget for). would NOT be detremental to the radiant heat, and that it would only lenghten the time it took for the system to get to target temp. He said that dense wood is second to concrete in terms of beneficial thermal mass is a radiant heating system, then only thing we were concerned with was the glue.
after the 1st winter with the extra mass it turns out he was correct. The heat worked the same as the year before, except it took slightly longer to get to temp.
the bigger issue was that I was not able to add as much mass as I would have liked due to budget, but since I used wide board pine screwed down to the floor, I could change this if I felt I needed to (only in my iso rooms) since the doors are still yet to be finished and i have been only mixing in here. That project has been slow to happen.