Insulation type under Gyp-Crete?

Kal Row

the uneven load bearing will cause cracks, use that 1/8" dense reflective foam pad - that has all sorts of fire ratings

kevin_5

What kind of insulation under overpour job?

Hey guys, What type of insulation have you liked to use best under the subfloor on an overpour job? I know fiberglass would work, but doesn't sound like much fun. I have used bubble wrap type on staple UP jobs. Has anyone used the spray on foam under an overpour? How much is recommended? This is my first overpour and I want to get it right. Any cool tips appreciated also.Thanks in advance. Kevin

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kevin_5

Thanks but...

Kal, I'm talking about insulating UNDER the subfloor. My understanding is you can't put anything between the GYP and subfloor. Do I misunderstand what you're saying? Kevin

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Jason Horner

There are several noise insulation membranes on the market that are sold by gypcrete companies which are used to minimize transmitted noise to floors below.

You'd probably still want a radiant barrier below the floor.

Recent studies I've read about the value of a radiant barrier under concrete *basement* floors using bubble-foil-bubble products suggest that they are of minimal R-value, but I'm not sure that the studies really took into account full radiant effects. That said, I'm still using foil barriers but I am looking for more info to prove/disprove their worth.

http://www.maxxon.com/index.asp
http://gypsumsolutions.com/

Kal Row

i have a sample of the stuff in my hand...

that i got at ish, cant find the sheet that came with it, cant belive they didn't stamp their name on it, how stupid, they said it could go right under gyp or cement no problem - it's very thin micro-foam with one reflective side - will let you know if i find the sheet

kevin_5

Thanks Guys

I appreciate it. Anybody else have any experience with this? Kevin

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S Davis

Insulation

All the jobs we do just use fiberglass insulation, R-11 between heated floors and R-30 over unheated areas.

S Davis


Apex Radiant Heating

hr

Gypcrete is used in hotels as a sound

and fire barrier. I have always used a simple fiberglass batt without any problem. The r value would depend on the space below. Is it heated below?

Insulation suppliers also offer special sound barrier insulation for partition walls, but again, I really don't see a need.

hot rod

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Weezbo

Friction fit ...same tune as Hot Rod.

and will add...foam along box beams and rim joyist.

Troy_3

Gypsum, insulation

we have one architect that specifies 3/4" polystyrene over the subfloor before we tube and pour the floor. We glue it down, tape the seams and use the 1-1/4" wirsbo staples to go through the insulation and into the subfloor. It makes for a thick buildup. We have done a dozen of these and it seems to work well. Most of our work is insulated under the floor with fiberglass. Icynene works great too. Most of our jobs don't get insulation between floors. I was suprised to hear so many guys at wetstock say they feel this is needed. we haven't insulated 1st floor ceilings in the last 13 years of doing radiant. I am curious to hear others feelings. Always looking to improve but only if it makes sense. Any opinions?

marc

rule of thumb

4 times the R-value of the floor above, this usually means r-11 will work, we suggest r-19 batts. marc.

Kal Row

ok - i found it...

http://www.low-e.com/application/application_view.php?Application_Name=Under Concrete

they said it was just as good under gyp

Unknown

foil barriers under slabs are junk. they are slightly better than nothing. they are not in any way comparable to foam insulation, solid R value, under a slab. Under slabs your heat loss is conductive, not radiant in nature.

foil barriers under floors are slightly better as you can actually get some radiant reflection benefit, however ORNL has info on this: http://www.ornl.gov/sci/roofs+walls/radiant/rb_02.html

basically, in walls and ceilings it's ok, but under floors you are looking at a 50% reduction in ability in anywhere from 1-5 years from dust accumulation.

There are no shortcuts and no miracle products out there. Get R value in your joists and below your slabs. Spray foam or rigid foam products in joists are good.

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Unknown

I don't even have to see it. If it is depending on reflectivity, it is not appropriate for an under slab application. You're looking at conductive loss there, not radiant loss.

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Unknown

it is just as good, sure. of course it's not very good in the first place!

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Unknown

If you're over a heated space, the RPA guidelines are R5 for hard surface floors and R11 under carpeted floors.

Over unheated spaces, R13/19.

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