Replies

1. 
   Piffin | Mar 22, 2005 03:10am | #1

   yes

    

    

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2. 
   mikeski | Mar 22, 2005 03:30am | #2

   Piffin is correct.  It makes sense if it's below the roof sheathing directly.  If there is still any airspace above the insulation, it should be vented. 

   "Be modest.  A lot was accomplished before you were born."

1. 
   zac1 | Mar 22, 2005 03:36am | #3

   thanks for the help, just thought the ridge vent would keep the attic space cooler but sounds like the foam directly under the roof sheathing takes care of the heat build up.

1. 
   mikeski | Mar 22, 2005 03:44am | #5

   Correct.  Is there already insulation in place and the foam is in addition?"Be modest.  A lot was accomplished before you were born."

1. 
   zac1 | Mar 22, 2005 03:51am | #6

   Yes, the installer will remove the existing insulation and put it back over the foam after the foam has set.

1. 
   mikeski | Mar 22, 2005 03:57am | #8

   .....woah....that means that the foam isn't being sprayed directly to the roof sheathing if they are removing then putting the existing insulation back.  In that case (if there is still airspace above the insulation but before the actual roof) you should probably keep the venting."Be modest.  A lot was accomplished before you were born."

2. 
   mikeski | Mar 22, 2005 03:59am | #9

   Unless it's batt insulation that will still fit inbetween rafters/whatever after foam has been sprayed."Be modest.  A lot was accomplished before you were born."

3. 
   MAsprayfoam | Mar 22, 2005 05:59am | #10

   Rcc-
   I read it to mean that they were taking the FG down, then spraying the foam, then putting the FG back on over the foam as perhaps fire barrier or just additional R value. So, foam against roof, FG against Foam.That accurate zac1? zac, where do you live? Stu

4. 
   zac1 | Mar 22, 2005 02:34pm | #11

   Stu,That's correct. I live in Charlotte, NC. So, the extra R-value is appreciated, esp. in the very hot summers.Z1

5. 
   MAsprayfoam | Mar 22, 2005 02:39pm | #12

   I'm in New England (Massachusetts) and am very surprised the foam is not used more extensively. I'm always hearing about it being used in the hotter climates more and more. Surprizing, that's all.

6. 
   ThumbWhacker | Mar 22, 2005 05:04pm | #13

   I'm in Charlotte, too, starting a home in Mooresville soon.  I've talked briefly with Carolina Foam Solutions, is that who your quote is from?  I'd like to use Icynene or a similar product and am gathering info.

   Thanks!

3. 
   tealwood | Mar 22, 2005 03:44am | #4

   agree that all vents should be eliminated.  would you mind sharing the amount of the estimate -------  $ per square fott at what thickness etc.????????????

1. 
   zac1 | Mar 22, 2005 03:54am | #7

   Sure, the installer quoted $1.25/sf for 3.5 inches. It graduates up from there if more thickness is wanted.

1. 
   Nuke | Mar 22, 2005 06:34pm | #14

   This actually isn't that bad of a price. Two years ago I got a quote from someone that worked the N.GA area and to spray in a whopping 1" thick (their price basis) was considerable more than your quote for 3.5". I got two quotes (all of two contractors I could actually find), and to do one basement room the quotes went from $1860 to 3200. I remember thinking of asking him if payment could be made in the form of pre-spun gold.

   Total surface area for me was about 415-420 SqFt., which is working out to $4.40 and up for an inch!?! At that point I went out and bought a pallet of Miraflex for less than $500. While I love the aspects of spray-on foam insulation, in my area its an ultra-luxury unless something has changed dramatically in that last two years (doubtful).

   Doesn't Ice. have an R-value of 3.5 per inch? There are other spray-pn foam products (Corbond?) that are about double that of Ice. For existing stick construction I'd imagine this is a terrific route to take. If its new construction I would imagine SIPs would be an option.

1. 
   zac1 | Mar 22, 2005 06:48pm | #15

   Nuke,That sounds about right for the R value. I have used it in an unfinished basement and the homeowner was really pleased with the result.Maybe as Ice is more in demand, the price will continue to fall. Hopefully for all of us that will be the case.zac1

1. 
   SGH | Mar 22, 2005 09:56pm | #16

   Here's a new one from a new member (been a suscriber for many years).  I'm a reasonably accomplished/experienced DIYer.

   I have a 2x6 rafter roof at 6/12 pitch and want to go to cathedral ceiling: roofing new 2yrs ago. My plan:  collar ties 4' oc, screw 2x6 (2x8?) steel studs to bottom of rafters (parallel, screwed thru flange) to get 11" depth w/o adding weight to rafters, and use blow-in foam or cellulose, block soffit and ridge vents. I expect to need blocking or furring to keep spacing correct for the steel studs. Do I install sheetrock before blow-in?

   Anyone with experience based thoughts on this?

   Thanks...