What Rob said about radiant-barrier- it's one of the most overhyped & mis-applied products ever invented.

That said, a foil or aluminized-fabric radiant barrier can be an extremely low VOC vapor & air barrier- just be careful where/how you apply it, since it dramatically reduces drying capability. (Perforated aluminized-fabric radiant barrier is both air & vapor permeable, if you're installing it primarily for heat transfer reasons.)

At relatively low temperature differences the efficacy of radiant barrier is pretty limited, since the radiated portion of the heat transfer becomes an ever-lower fraction of the total. It's best performance is when it has at least 3/4" of air on both sides of the material- no direct contact and the temperature differences 40F+. Radiant heating systems are inherently low-temp- radiant barrier is more useful behind steam radiators than under low-temp staple-up radiant floors, where the warmest part of the floor or sub-floor is typically less than 20F above the room above or below. Higher temp suspended-tube radiant would see some measurable benefit from radiant barrier, but for tubing sandwiched in above-the-subfloor systems, fuggedaboudit.

In staple-ups with aluminum heat spreaders, the bare aluminum is sufficiently low-emissivity that the radiated portion of the heat transfer downward ends up being quite small- little benefit to be had from RB there. The wood subfloor is much higher-E, but lower-temp, and a small fractional area of the total downward facing surfaces. Snugging up fiber or foam insulationg right up to the heat spreader plate would typically be more effective than adding radiant barrier with an air gap, since it limits convective losses and potential thermal-by-pass air currents laterally in the joist bay.

That reminds Dan,

I am designing a system using RetroPanels from MrPEX. No wood, no glue, no caulk, no VOCs.

... made of plastic, has plastic foam. I doubt that will fly with a chemically sensitive person.

I am not familiar with the Retro panels, But I do like a surface mount system over a staple up,
Better fuel efficiency, easier to install,
the use of a 24x12 heat plate and a 1x4 is about as chemical free as I can offer......
This application was used over a un level concrete slab with 2x4 and shims, This application off set a 4 inch slope, bubble foil bubble (I know) was placed under system in air pocket, 3/4 ply was finished floor attached to 2x4 12 pattern.
Clever and cost effective and a "soft " finished shop floor.
Dan

Thanks, Dan.  Do you think this system is easy enough for carpenters, who have never done radiant other than in a slab, can install with the help of the plumber's guys (the plumber said his labor would be astronomical for this and is pushing the gypcrete).

By the way - does anyone know if gypcrete has chemical stuff in it?  can't seem to get an answer and if we have to go with gypcrete or lightweight concrete, I'd like to know the difference.

Anyone have negatives about Johns Manville Formaldehyde-free fiberglass other than the fact that it's fiberglass (I know, I know)?  Having a hard time with issues and costs of all others still.  Cellulose is the newspaper, correct?  Is there another cellulose I'm not aware of?

Thanks again
Jill

cellulose is newspaper, basically. it may have fire retardant or pest repellents but there are DIY cellulose kits that may allow you to avoid some things. not sure about fire code in your area though....

Sandwich installs (light plate and tubing, or for high output, heavy plate and tubing) are not that much more work than quik trak. the hardest thing is cutting the return bends, and any decent carpenter can spit those out en masse without working too hard. Ripping the sleepers is also easy for most carpenters if you do go with a sheet good product.

the actual "heating guy" work can be restricted to plate and tubing install... or the mechanical room, if he balks at that too.

If you get any prefab return bends or the like you better be sure of what they make it out of. I'm not sure the RHT sandwich system uses no-voc plywood or anything... can't imagine it is.

Boy I wish you guys were in Colorado.  (Actually, with this fire -- I'm in Boulder -- we'll be needing lots of good contractors/subs out here very soon...it's tragic).

If these guys need advice/consulting, does anyone consult long distance?

Cellulose is indeed newspaper, but about 15% inorganic (non-volatile) fire-retardent chemical by weight. The "better" versions use borates (usually boric acid), since it functions as both a pesticided (it's toxic to ants/wasps/bees/termites that might eat or use cellulose for nesting material) and as mold-inhibitor as well, beyond it's mere fire-retardent characteristic. All commercial cellulose insulation sold in the US has some borate content for the mold/insect aspects, but some also combine it with (much-cheaper) aluminum sulfate as fire retardent. Borate-only is the preferred grade, since sulfates will react with many metals when the humidity is high (making copper in to copper-sulfate, for instance). Borates are inorganic, completely non-volatile, and have very low toxicity to humans (they're routinely used in soaps/detergents, cosmetics, & medicines). A typical all-borate dry-blown cellulose material safety data sheet looks like this:

http://www.nationalfiber.com/docs/M...202009.pdf

The only potential VOCs in dry blown cellulose will be from the ink on the paper stock. Wet-sprayed or "stabilized" cellulose contains water activated adhesive, so you're probably better off sticking to a dry-blow product to be sure.

If newspapers don't bother you, cellulose is a preferable material to low density fiberglass goods on a number of levels (protects structural wood from absorbing moisture and creating rot/mold conditions, does not lose performance at high temperature differences the way low-density fiberglass does.) It's relatively cheap compared to any of the higher-end blown fiberglass products that would outperform it.

If going with a fiberglass product, super-fine goods like JM Spider or Certainteed Optima blown-in-blanket systems blown to ~1.8lbs density has cellulose-like R-stability over temperature, and a higher R per inch (and per pound, if weight loading at high-R is an issue.) Spider is formaldehyde free, but contains a water-activated adhesive similar to wet-sprayed cellulose (not sure if the adhesive contains any VOCs, but as a product passes a SM-2010 VOC Emissions test with no hazardous emissions. That may or may not be relevant to the chemically sensitive.) Optima is similarly formaldehyde-free, but has a Greenguard Institute certification for low VOC. SFAIK Spider doesn't have this certification, but almost all Certainteed products do. If not cellulose, Optima or Spider would be my pick, even though rock wool is inherently zero-VOC.

Now your just showing off Dana hehehee.

Anyone heard/used Roth Radiant Panel Subfloor systems? Looks like it is EPS foam, which might actually be inert enough not to cause me probs, and resolves insulation choice issue...

IF eps is inert enough for you, Roth is great, but if you want to nail any wood over it it's a bit of PITA... you have to rip all the panels in half to install sleepers.

it's high output and a good product though. We use it in slab retrofits because it gets the insulation and radiant layer down to the lowest profile possible.

Is there any OSB in it?  We'd be putting a floating floor over so hoping no nailing needed, but maybe...

no, it's just EPS, Aluminum, and whatever the bonding agent between the two is.

Kind of like "RetroPanels.

Ok what we're going to do, unless anyone has any objections or better ideas for chemically sensitive (extreme) me, speak now or forever...

Anyway, what we're going to do for main floor is 1 1/2 inch portland concrete (I know, yes it is engineered for that). Radiant in that. Engineered hardwood over that. At this point, 2 layers of double bubble foil wrap beneath for insulation. Or maybe UltraTouch jean batt, but I'm still not happy they are using used jeans now and not just jean scrap overruns.

I'll let you know how it goes. Again, please speak now if this is a bad idea. Oh, and also, I heard we should wait months and months for the concrete to completely cure (same with basement slab) before sealing it and/or covering it with something. Is this true? I don't actually want wet cement as I'd like as mold-free life going forward (in my home at least) as possible.

Thanks for all the help.

Engineered hardwood has glue in it. You can't use stained concrete or tile?

What will you use for air filtration/purification?

Did I miss something?

Hasn't anyone mentioned that bubble-foil is nearly worthless in ANY application, but more especially in radiant heating applications?

One could make an argument for walls with air space (Dana), but under a floor...ridiculous!

Please stop wasting your money on bubble-foil radiant floor or otherwise. I know it's shiny and all, but seriously.

http://www.healthyheating.com/Page%2055/Page_55_o_bldg_sys.htm

For the engineered flooring it's actually an eco flooring that has no offgassing as far as I researched and tested -- it will either be EcoTimber or Kentwood.

We're going to use an HRV, although I'm still trying to figure out which one and where best to put the intakes and exhausts

Ok now I'll really look into that -- I am just desperate for using something that isn't going to affect my sensitivities and all of them do so far.  And are really expensive. 

Is it a waste because there's no significant R-value or because it doesn't block the heat from coming down into the basement?

I'm not as concerned with R value as I am with not losing the heat to the walk-out  basement (which will most likely often be heated and used - it's a living space)

Am I still being naive?  I will check your link.  Thank you!

What would you suggest? 

Have you ever heard of a product called Radiocity (sold by Greenbuildingsupply.com)?  It's a spray on product.  All glass particles...

Ok I just read the link - thank you for keeping me from making a mistake.  Back to the drawing board on which insulation to use then.

I had a hard time with the Johns Manville formaldehyde-free.  Wool is too expensive.  Spray foams I don't tolerate.  I could wing it with the UltraTouch and hope I do ok.  Will they still make me put foil above that? 

What about using Blueboard?  Is that a dumb question?

Now I can see why so many people with chemical sensitivities do not use radiant on their second floors.  It's really hard to come up with a no-voc system that is also effective.