Replies

1. 
   rez | Jul 26, 2007 06:31am | #1

   Greetings homebuilder,

    As a first time poster Welcome to Breaktime.

   Insulation data is a common discussion here and you may be interested in the archive listing of old threads in Breaktime concerning such.

   If you scroll up in the upper left corner of your screen there is an advanced search function that will take you to a page of instructions directing you to previous threads dealing with whatever you type in the search bar.

   If you type in 'foam insulation', 'dense cellulose'  or other keywords of the subject matter you'll get a supply of data from those old threads.

   Cheers and brew yourself up a hot cup of java 'cause there's plenty there.

   "I would rather sit on a pumpkin and have it all to myself, than be crowded on a velvet cushion."
   -Thoreau

1. 
   BillHartmann | Jul 26, 2007 05:37pm | #2

   "whatever you type in the search bar."The advanced search does not have a"bar". it opens up a new page with lots of options.But there is a search "BAR" at the top of the page, but that brings up archive FHB articls that are for sale.Also search on MOONEY WALL..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

2. 
   frenchy | Jul 26, 2007 09:43pm | #3

   homebuilder6

      It's more complicated than that!

    

     consider other options such as SIP's or ICF's

     those two radically differant systems offer some great advantages over tradional stick building when it comes to energy savings..

    In general SIP construction  is slightly more energy efficent than ICF's but ICF's have other advantages..

     Your total finished costs will depend on many factors, such as will you do-it-yourself or have someone do it for you? 

     The differance in costs shouldn't be more than 2% in either case over traditional stick building.  If you are a do-it-yourselfer you could possibly save tens of thousands with either of those two systems and they make it real easy to D-I-Y.

    OOps! I'm ahead of myself.. 

    I used jargon and I shouldn't have..

    SIP's stands for Structural Insulated Panels and they've been around since the 1940's.    They are a large block of foam with OSB on either side..  about 200% stronger than stick built houses  and no thermal bridge every 16 inches to worry about.. Very fast to build with compared to traditional stick building. I've seen experianced crews put up a house in a day with them..

     ICF's is Insulated Concrete Forms,  basically Large foam Leggo blocks that you pour concrete into to make basements and walls with.

    Each block weighs maybe 2 pounds, go together llike large leggos and is extremely DIY friendly. 

     ICF's are rated for 200 MPH winds and have a 2 hour fire rating.. Plus they aren't affected by insects such as termites or carpenter ants.. Their energy efficency is slightly lower than SIP's but massively higher than other building methods..

     A typical basement and single story home is easily a week DIY project.  a second story could add another few days. 

    

1. 
   homebuilder6 | Jul 28, 2007 01:25am | #5

   Thanks for the input.  Though I've read about SIP's and ICF's in FHB, I haven't yet had the opportunity to use them, and therefore didn't consider them for my house.  I'm already about  half done stick framing the house.  I've now read the major  threads on the the Mooney, which sounds very interesting.   But I'd still be interested in knowing what people  think (if forced to choose) is better between FG + foam board (should it be on the inside of the house in colder climates?  a recent article in FHB had it described as an exterior application) or cellulose.  I'm thinking it's going to be cellulose, but I've read that its R value is also idealized.... and wouldn't stopping thermal bridging be better?

1. 
   frenchy | Jul 28, 2007 01:34am | #6

   homebuilder6

       Both celluliose and fiberglas are massively affected by moisture.. R values drop to near zero with a relative little amount of moisture.. foam is unaffected by moisture..

1. 
   DanH | Jul 28, 2007 03:54am | #7

   Frenchy is down on cellulose because of problems in his home. Most folks have no trouble with cellulose, and it's superior in several ways to other options: Cheap, ecologically sound, easy to retrofit, and good at blocking air infiltration in existing structures. For new walls it either needs to be installed wet or be installed behind netting or some other retaining mechanism prior to installing the interior wall surface. For attic insulation it's equally good whether installed new or retrofit.Fiberglass is moderately priced and easy to install in new structures. Unfortunately, it loses most of its insulating value if not tightly sealed in a wall (and it's amazing how "unsealed" even new walls can be). Though it's used a lot in "blown" form for attics, that use is questionable, since the practice leaves the fiberglass exposed to air circulation in the attic.Foam (sheet or sprayed) is more expensive. Installation ease (which can drive overall expense) varies depending on the structure and the type of foam. Foam generally does not lose insulating value if not tightly sealed (though obviously air blowing through cracks, eg, between foam boards, is still a problem), and sprayed foam helps to seal structures against infiltration.Regardless of the type of insulation installed, control of air infiltration is more critical that the absolute insulation R value. Better to have a tightly-sealed wall with an honest R11 than an R30 wall where you can feel cold drafts blowing out of the electrical outlets because of infiltration.
   So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin

1. 
   frenchy | Jul 28, 2007 05:55pm | #8

   DanH

     the R value of insulation is tested under laboratory conditions. 70 degrees and humidity tightly controlled..

    real world is different.. as you point out, it's amazing how even modern homes can leak air thus any insulation which is affected by moisture as cellulose and Fiberglas are need to be adjusted to real world ratings..

    There are several articles in technical journals about thermal pumping.. Fiberglas which is very good at allowing free air movement (it's what they make furnace filters out of ) is particularly bad at it. if the interior wall is at 70 degrees and the exterior wall is at say zero there is a 70 degree spread inside say a 3 1/2 inch cavity

   Warm air rises, cold air settles. so within that 3 1/2 inch cavity we are mixing 70 degree air with zero degree air and that is bound to waste heat.. add just a little bit of air leakage and a furnace or fireplace or water heater that draws inside air to combust and you've created a mini-vacuum.  Sucking cold outside air in to replace the warm heated air that was burned and sent up the chimney. 

    Foam while more expensive initially isn't affected by moisture at all, seals air movement completely and adds stiffness to a building would appear to be the superior insulation.. other insulation have the advantage of cheaper initial price.   

    We all know not to take the lowest bid on something, or at least we should know. Now if you plan on flipping this house soon then it doesn't make sense  to spend any real money on the isulation. We know that appliances and pretty stuff sells homes, not insulation or quality.  If you are figuring out return on investment for a home that you intend to live in for a while,  that calculation is compounded by the rising cost of energy. I know I pay more for energy today than I did a decade ago.  I could look and see exactly how much more but I suspect it's about 1 1/2 times more. Assuming that's correct and will remain correct for the foreseeable future you could use that factor to adjust  your future costs..

     What can't be calculated with any real degree of certaintee is what new insulation will gain you.. In my case it lowered my bills by nearly $400.00 for the two worst months of the year plus significantly lowered it the rest of the year.  Nobody should make that big a claim for you however.. but even a reasonable guesstimate chould mean a 50% reduction in costs using foam over fiberglas.

2. 
   BillHartmann | Jul 28, 2007 06:21pm | #9

   "Foam while more expensive initially isn't affected by moisture at all, seals air movement completely and adds stiffness to a building would appear to be the superior insulation.. other insulation have the advantage of cheaper initial price. "That depends on the type of foam, the climate, and the details of the structure.There have been problems with moist air moving through foam and condensing and no way for it to dryout..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

3. 
   frenchy | Jul 28, 2007 06:33pm | #10

   BillHartmann,

    What I suspect you are refering to is improperly installed SIP's.. Where there isn't a proper seal between panels and that allows vapor, water ladened air to move thru the panels and cause problems..

      Nobody can prevent poor construction, or mistakes,  it happens all the time. If you know what to look for it's easily caught at an early inspection..

     As for sprayed foam, if an area isn't sprayed and sprayed properly that's clearly visable if you know what to look for.. most localities have insulation inspections prior to close up..  

4. 
   BillHartmann | Jul 28, 2007 06:35pm | #11

   No, I am talking about sprayed open ceil foam.In some applications is needs a separate vapor retarder..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

5. 
   frenchy | Jul 28, 2007 06:47pm | #12

   BillHartmann,

    Absolutely.. while it may perform the vapor barrier role, the studs themselves do no such thing..

    Well said!

6. 
   BillHartmann | Jul 28, 2007 07:04pm | #13

   You weren't listening.The problem is not the stud. Is the type and place the foam is used.MOISTURE CAN MOVE THROUGH SOME FOAMS AND IN SOME PLACE CAUSE PROBLEMS..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

7. 
   MrEnergy | Aug 08, 2007 12:21am | #14

   Your 'guesstimate' of 50% savings ... is in fact very reasonable as fiberglass has about 1/2 of the R-value. Add the benefits of better air sealing, and you're doing well.

   Laboratory tests is all we really have to create standards by which to compare, so we shouldn't bad mouth them ... but simply keep in mind their limitations. R-13 or other HD fiberglass will minimize the allowance of air movement due to the higher density. We claim glass is a very poor insulator, but yet we use it for insulation ... go figure. It's because it is the air pockets that do the insulating, not the material itself. Properly installed, fiberglass should do well. Cut it +1/4" -0" and eliminate all voids w/ proper tucking. A typical enclosed wall w/ sheathing and caulked seams/penetrations (e.g. exterior outlets, should minimize air flow into the wall and the subsequent affect of air leakage. You insulate and old barn wall, you don't get much, you insulate a properly constructed wall intended to enclose heated space and you should do fine.

   I'm not arguing for one or the other, just trying to maintain a proper perspective. Remember, everything has a time and a place. And EVERYTHING has both advantages and disadvantages.

   Cutting rigid foam to fit is a tough job and a tall order ... not for most applications. Spray in cellulose is a great way to go ... albeit messy, but it does help w/ the cracks, gaps, and other misc. small areas to minimize air transfer.

   Pay your money, take your choice. Choose the one that is best for your application. Not an easy decision, but like everything, requires some thought. Ain't NO free lunch ... even if you bought mine for me.

8. 
   frenchy | Aug 08, 2007 01:08am | #15

   Mr Energy,

     The two alternatives you neglected to mention were spray in foam...very fast and effective for those who must use sticks (er,... 2x4's or 2x6 to build with) or SIP's which eliminate completely the thermal bridge provided by those 2x4's or 2x6's

     Gaining ground quickly are ICF's.   In my area there is currantly no more than  2% permium for a ICF constructed home and most of that winds up in the builders pocket.  Some builders are bidding the same as stick builders and providing the energy savings as an incentive to select them in a tight building market..

     You entirely missed the point about air flow thru fiberglas.  If the outside wall is at minus 30 degrees and the inside wall is at plus 70 degrees..  inside the stud cavity the cold outside air will fall (it's more dense) and the warm inside air will rise.  (the principle that a hot air ballon operates on) 

    In that little 3 1/2 inch space you have air movement  warm air mixing with cold air  the resulting scrubbing action takes heat away faster than it's labratory rating indicates. 

     You'd have no scrubbing if the lab is tested at 70 degrees and the inside temp is at 70 but change the conditions to real world conditions and watch your R ratings plummet..  To that problem add the effect of thermal bridging from the studs and suddenly fiberglass performs very poorly in the real world..

      Yes there is such a thing as value engineering.. Why pay for more insulation than you need?   Well don't forget insulation not only works at keeping heat in  but also keeps cooled air (air-conditioned air ) inside the house where it can do some good. 

    In a temperate climate like say San Diego where A/C isn't needed much along the ocean front and heat is almost never required perhpas the value of Insulation is overrated.. I 'll grant you under those conditions you may be correct..  

3. 
   curley | Jul 26, 2007 11:22pm | #4

   do a search on the "mooney wall"