Metal house, e-foil, radiant floor heat ????

Unknown

I stopped reading your post as soon I saw the words "double bubble" this stuff is CRAP, try another design with better insulation values before it`s too late. Don`t fall for "equivalent" R values either.<BR><BR>Dave

RandyJ

Metal house, e-foil, radiant floor heat ????

I could use some good advice/help with this project. My plan has been to build an "all metal" house on a concrete slab with radiant floor heat. The design is to use a post & beam structure, metal roof & siding with e-foil/radiant barrier, a.k.a. "double bubble". Here's my situation in question... I'm pouring 12" x 24" footings. On one side there will be piers which will be poured in 8" holes drilled thru the fill dirt to hard pan ground. Original design was to wrap entire slab and footings with vapor barrier plastic and 2" styrofoam insulation. This was to be one pour. It seems far too much to do at one time and I'm now thinking of just pouring the piers and footings then put down the vapor barrier & styrofoam, then pour the slab with the re-bar and radiant heat tubing in it. Problem that puzzels me... the posts (6" I-beams) will be anchored to 36" x 36" x 24" pods. If I pour as the new plan is then the slab & styrofoam will be on top of these "pods" of concrete which will obviously cause problems with anchoring and zillions of other problems... I'm looking for any advice, comments, suggestions, etc....anything will be of help... the TRUTH about the "double bubble" would be nice too!

Bernie Riddle_2

dubble bubble trubble

Ya left a contractor talk me into it for insulation under my radiant slab in my basement. Now have low return water temps and cold spots due to lack of insulation under slab from what most who have looked at it tell me.

Stay away from it IMO

RandyJ

not for floor... I ain't stoopid.....

I couldn't imaging using e-foil for a radiant barrier in the floor. It is totally the wrong application. That is definitely where a thermal break should be and perfect for plain ol' styrofoam... stoopid to use the stuff there. From what I know of it, a radiant barrier is a good house wrap and heat reflector... not a good design at all to put it under a "heated mass" such as a slab floor. My intention is to use it on the inside of exterior walls & roof... supposedly that's where it is designed to go and it's function is supposed to be to return heat to the room rather than to slow heat loss... two distinctly different concepts. If it works then KEWL, if it don't then it don't... I'd really be satisfied if I knew why it does/doesn't work.

Unknown

OK Randy

I only said what I said as I have witnessed many a "cheap skates" put this "double bubble" under their radiant concrete slab as they were "fooled" by all this "equivalent" R value crap. As far as any other applications for the stuff goes, like you, I`m all ears!

Dave

Gordy

trouble picturing

Is this close to your plan A ? Skip the bubble foil for anything. For the price there are better products out there that will give you more bang for the buck. Mark Eatherton posted something about skewed R- values for the stuff they got called on it.

Gordy

RandyJ

drawings...

Thanks gordy & dave. I did some sketchy editing to the drawings to show what ideas I'm playing with. As for calling in a contractor... I do a little of that myself...and I got no money to pay some yahoo to do what I can do myself. Around here they're overpriced and don't know as much as I do. I'll put the edited drawings in another post... thanks
RJ

RandyJ

Drawings

Here's my editing of your drawing to show my original design. I've noticed that in most other designs that the insulation is under the slab but not the footings. That has been a big concern to me as the footings & pylons would wick the heat out of the slab IMHO...

I'm also showing a couple of pics from Heritage All Steel Buildings where I got the idea for this type of construction.

RandyJ

Here's another idea I'm looking at. The drawing is a little rough but it conveys the idea. The anchor bolts are not shown. Although most drawing show a 6" slab I'm seeing alot of 4" slabs being poured for residential floors. I'm using 1/2" steel re-bar 12" o.c. and pex-al-pex on 12" loops, doubled next to outside walls ....

RandyJ

forgot to attach the pic...here it is.

Pic Attached

Ted_9

R-values and infultration

Use the highest r- values that you can. You're going 1/2 pex 12" O.C. It may work but some engineering should go into this project before the floor is poured.

Massachusetts

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RandyJ

What's an option to double bubble?

One thing I don't like about the bubble stuff is that apparently it will burn like plastic... I'm looking for a good reflective barrier that is cost effective...so what do you suggest...since apparently there are some strong opinions against it....
RJ

hr

If you pour the footing piers first

install the long anchor bolts in them. Then install the 2" foam over the pier.

I'd check with the structural engineer first of course. they make high load foam for under airport runways, etc. I used some Dow high load 60 psi under a heavy equipment shop once.

Also be sure to detail that edge insulation some how. Here is a detail I use. I'd like to see a long "leg" on the foam cover of that Z flash/ rat guard. Sloppy metal work in this pic however and it wasn't backfilled yet.

I know the metal building guys around here like to do those monolithic pours with the post footers poured with the slab. I've yet to find an insulation detail for that method. And it tends to promote slab cracking with such a thick spot transitioning to a 4 or 6 inch slab.

hot rod

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hr

Yes those reflective products work great

under roof sheathing. They use that product in poultry barns around this area. It does a great job in that application. Those are fairly open barns however and R value is not addressed with that reflective layer. For a home or shop you would still need an R value somewhere in the build up.

Lots of contractors spray foaming right against the metal roofing these days. I had mine done that way about 4 years ago. incredible infiltration layer as well as R value.

Just don't let them tell you 1" is adaquate. Mine averages about 6" thick.

Check at buildingscience.com Joe has good data and drawings of insulation how and whys.

hot rod

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RandyJ

spray foam

Thanks guys. I've got 2" eps for the under slab insulation which was highly recommended 6 months ago. It is 1.5#per cubic ft. Not the same as the blue stuff from DOW..but when it's covered with concrete who give a fat rat what color it is... it will work with the load on it and has good crush factors. I'm very confident in the design although I do want to tweak the footings and I agree with you about the monolithic pour creating stress fractures. I feel pouring 16' x 32' x 4" slabs on top of the styrofoam will give better resistance to cracking by uncoupling the slab from the footings. That principle works great when using uncoupling methods to prevent cracking tile floors. FOAM>>>oh yeah, I've read about the spray foam used under the roof decking. Some good reviews on studies done in Florida... I don't know of anyone in this area who can do it and may have to rely on rolls of insulation. The old standard has been 6" insulation with a white plastic backing. I'd be afraid of the fire hazzard with the sprayed on foam. My whole idea is to have a home that is totally rot-free and can not burn and won't feed termites. Built right it won't rust either.

G.Kaske_2

Codes

Randy I don't know what the engineers or building inspector might say about foam between the footing, and slab. Or under the footing. I don't think I would do it.

It depends on where your steel columns are going to bear on the slab or directly on the footing? The pics show on the slab.

If on the footing then the insulation may not be an issue. On the outside footers stop your foam board so it covers the inner third of the footer let the perimeter insulation do the rest.

Usually in commercial buildings columns rest on the footings. then diamonds are poured around the columns. When stripped expansion material is placed around the diamond then do the floor pour. This reduces cracking emmiting from the column, which would happen if it were monolithically poured.


Gordy

Weezbo

Here is a thought..

the picture # 3 i would modify a shade...instead of having the footings edges square cut them wider and at an angle back into the footing insulate that diagonal also with 2"...
another thought is Hot Rods idea with the long bolts is savvy..going with that idea a bit further.. look up a site Compositec.com

it makes some material that makes displacement of the foot print of an elephant indeterminable with a footprint of an ant. there are many metal buildings going with these pads these days...there are also many people at this product and others like them...meaning it may be available in your area.

the high density insulation is a shade spendy though hammer jacking the slab can be also.

Remember what i said about a vapor barrier.

the metal Z flashing gets the water away from the building and keeps it out there where it belongs..:)

running some electrical conduit under the foam from the service entrance to the branch circuit feeder is also a good idea while you have the shovel in your hand.:) it allows you to get there from here without taking a drill to the building...Quite often the largest termites on the job are the sheetmetal,eletrical and plumbing contractors.....

*~/:)