Replies

1. 
   fortdh | Oct 22, 2003 04:31am | #1

   Rob, I recommend a closed cell polyurthane foam sprayed at 1.7 to 2.0 # density. It is sprayed after the wiring and everything is in the wall. It will coat all it hits. You can go with 1" of foam, and follow with batt for best bang for buck.(about R 25-26, but more important than R-value is air sealing)

   I would do the attic floor (back side of sheetrock) and then blow in cellulose. In bays with duct work between floor joists, I would foam in the duct. Be sure all joints are taped.

   The foam is going to seal the house very well, and add stiffening to the walls. Paul

   Energy Consultant and author of Practical Energy Cost Reduction for the Home
1. 
   RobKress | Oct 22, 2003 04:48am | #2

   Paul,

   Thanks for the reply.  I am really excited about the idea of not having to caulk all of the air gaps in my "rough" framing.  And using fiberglass over the foam really makes a lot of economic and practical sense to me.

   Thanks again for the info,

   Rob Kress

1. 
   fortdh | Oct 22, 2003 06:21am | #3

   What kind of heat/cooling system have you planned?

   Will the house have nat gas? You have the opportunity to do many things right, and save a bundle both up front and in the future.

   PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home

1. 
   markls8 | Oct 22, 2003 08:55am | #4

   Paul, I too really like this idea. I wanted spray-foam in my just-constructed house and my builder wouldn't go for it. I had to fight (and pay dearly) for anything out of the norm for this house. Ended up with FG batts in the walls, "the worst insulation that money can buy".

   Now I'm running the show in the finishing of a 900 sq. ft. self-contained in-law suite/ loft apartment above my garage. I need to have the insulation done soon because the floor is IFR with PEX tubing in 1 1/2" concrete and will freeze if I shut it down and I don't want to heat an uninsulated room all winter. It's a Southern Ontario location, just across the lake from Rob.

    My question is - if I put 1" of spray foam and FG batts, do I still need to place a vapour barrier on top of the 2X6 studs? This would seem to create a two- VB situation with the FG batts between, although without the VB  it would seem that moisture from inside the house would pass through the FG batts and condense on the inside of the 1" of foam. The R-value of only 1" doesn't seem to me like it's enough to create enough temperature-dewpoint spread to prevent this. Do you have any longer-term results or short-term observations of these installations?

   I would also like to have the foam sprayed on the underside of the rigid pink foam which is under the slab which forms my cold room roof to seal it from water penetration (just in case it ever decides to try and leak).  Do you think it would perform this function if I got the # that you recommend?

   One downside for me- the foam guy is a 1+ hr. drive away. (But I digress).

   Thanks in advance. -Brian.

1. 
   fortdh | Oct 22, 2003 04:47pm | #6

   Brian, sorry you didn't win the battle with your builder.

   The foam in your 2x6 wall will yield R-7 (closed cell poly. But it also stops air flow which carries moisture with it. So I would not think you would need the inside barrier. BUT, be sure that all the penetrations are sealed. 1" will not be deep enough to seal wiring and plumbing cuts. The good installers spend a lot of time squirting some pink foam into all pass throughs prior to the general wall spray job. You could do that yourself with some cans of Great Stuff or the latex foam.

   A layer under the other location wouldn't hurt.

   RE 1 hour drive, I know a foamer who will travel 3-4 hours for a house job. Get all you can when he is there, foam back side of shower stalls, under hot tubs etc.

   PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home

2. 
   markls8 | Oct 23, 2003 05:42am | #7

   So the consumer-grade latex foam and Great Stuff are acceptable-quality products for this purpose? That DIY suggestion around penetrations seems like a good "upgrade" from simply using batts alone.

   Thanks Paul.

   Regards - Brian. 

3. 
   fortdh | Oct 23, 2003 06:30am | #8

   Yes, those products will fill the gaps well, the ones you can find.

   The air leaks come first, then the insulation.

   I did an energy audit for a client 2 years ago. He wasn't concerned with his energy bills ($900-1200/mo) but with his comfort. Had super insulated exterior walls, paid for a lot of insulation in the attic (about 20 inches of blown fiberglass).Beautiful house in the $1.2mil range.

   However, his varied ceiling heights left many interior walls open in the attic. I could see his slab floor on either side of fireplace, next to built-in book cases etc., from the attic. This is an extreme leak, really poor construction. In effect, his interior walls were "exterior walls", full of cold air in the winter. The wiring passages helped spread the flow of cold air. I have seen the same problem with drop ceilings in baths and kitchens. Also have seen a lot of light from partition walls and behind crown molding where the sheetrock was not taped.

   All openings into the living/conditioned space need to be sealed. Other wise, the insulation serves as a dust filter as dirty air flows through it. This is the main reason I recommend a first layer of spray foam.

   Some will say it is too expensive. Leaky insulation is no bargain.

   Brian, this dissertation is not aimed at you, but meant to be helpful to all who are considering attic insulation, sealing, R-value etc.

   PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home

2. 
   RobKress | Oct 22, 2003 02:09pm | #5

   Paul,

   The house is a standard colonial affair (3400 sq ft on the upper floors and 1300 sq ft in a finished basement).  The heating is a forced hot air system (natural gas) with 4 zones.  In my breakfast room which extends out over the walkout basement (12 x 16) I am putting pex in the floor not to heat the room but to just make sure that the floor isn't cold.  Wall construction is 2 x 6 but there are a ton of windows in the place.

   Thanks for the interest,

   Rob Kress

2. 
   CloudHidden | Oct 23, 2003 03:21pm | #9

   What are you assuming for the cost of the polyurethane installed? What about the fiberglass? What about polyicynene?

1. 
   fortdh | Oct 23, 2003 08:31pm | #10

   Here are some prices I got locally, and with the statement from a contractor that they should be pretty safe (meaning high enough) for estimating most anywhere. I have seen comments on this site that refer to prices both higher and lower than these.

   2# poly foam installed , 3" thick $2.25/sq ft

   1/2" .65

   1" .90

   R-21 contractor batt (not avail at HD) .75 installed

   Best deal per my contractor friend is 1" foam with 6" batt (slightly compressed) for $1.65 sq ft, or DIY .90 foam job plus .60 for the batt = 1.50. wall would be R-25+.He only uses polyurethane, closed cell for foam. It is quite rigid when cured, yellow/orange color.

   Unless the only way to get needed R value is total foam,( like only 4" available and lived in Montana) friend does not believe foam beyond 3" is cost effective.

   If you go to do it yourself.com,then hit build remodel, insulation, determine R value, and zip code, you can get some installed estimates. I do not know how dated the prices or realistic.Hope this is helpful. PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home

1. 
   CloudHidden | Oct 23, 2003 09:13pm | #11

   For the houses I'm involved with, we use be/t 3 and 4" of the polyurethane. Beyond 3" does little good the more south you go, while up to 4" is still beneficial in high heating-degree day climates. Beyond those thicknesses, the calculations show limited marginal utility. Be/c of what we build, we have to use this foam this way. For frame houses, though, I've not before seen the combo of puf and batts. Could be my limited perspective. I'm thinking that if I built a frame house though, I'd just go full-depth foam, and possibly icynene.

   Anyone here besides Paul contemplating using both puf and fg on their client's houses?

1. 
   fortdh | Oct 23, 2003 10:51pm | #12

   Cloud, In a 2x4 wall, my contractor buddy rec 1/2" foam, and 3 1/2" batt. This is slightly compressed, but gives the air seal plus good R-val at fairly low cost. Many will push full depth foam, and it would yield a much higher R-val, but friend is advising best effective wall for cost.

   Be interesting to see what others reply. PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home

2. 
   RobKress | Oct 24, 2003 02:47am | #13

   Paul,

   Here's the big question.... do you tyvek with this system of 1/2 and 1/2?

   Rob Kress

3. 
   fortdh | Oct 24, 2003 06:46am | #17

   Rob, I would tyvek because done correctly, it gives a good air barrier, but I rec tarpaper for sheathing exterior moisture protection.

   Stopping air flow is key to reducing wall condensation as well as the most important aspect of effective insulation, and a foam layer will seal a wall.(as discussed earlier, all penetrations have to be sealed as well)

   If you feel 5" of foam yielding R-35 is necessary, then fill the wall.

   Not positive, but think DOE recommends about r-19 for your area as cost effective.

   My contractor friend could have done any method he wanted to in his own house. He went with the combo, and he has been in the insulation business a long time.As a personal friend, I asked him to do the most cost effective package on my son's house about 7 years ago. I told him the cost over the builder package was my gift. He had his crew foam/fg the walls and rims and 1/2" in the attic before 15" of blown cellulose. No house in the sub-division could come close to the utility bills. I asked him again two weeks ago what he would put in a house today if it was his own. His answer, " 2x6 walls, 1"foam,fg walls, 1" foam/15" cellulose in the attic."

   In this area,5" will cost about $3.00 sq ft of foam.(R-35) 1" of foam plus fg will yield R-25 for $1.65 sq ft. So you get 40% more r-value for 80% more cost with the full foam. Now you only have to work out how many years it will take the extra r-10 in the wall area to break even with putting the extra cost in a bank CD, or some other part of the house with better pay back.

   Note this same discussion is going on in the next chat in this folder.

   Hope this is helpful to you, Paul

   Energy Consultant and author of Practical Energy Cost Reduction for the Home

4. 
   RobKress | Oct 24, 2003 01:56pm | #21

   Thanks again for the info Paul

   Rob Kress

5. 
   rez | Oct 24, 2003 04:32pm | #22

   Starting to sound like an earlier winter.

    

    

6. 
   fortdh | Oct 25, 2003 02:47am | #23

   Rob, Is your e-mail add correct as registered with this forum? I tried to send some info to you that didn't go through. PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home

7. 
   RobKress | Oct 25, 2003 03:13am | #24

   Maybe not, Paul.

   I will check it out....

   in any case, it's

   [email protected]

   Yes, I have recently changed email and such.  So it might need to be updated.

   Thanks

   Rob Kress

3. 
   delyosius83 | Apr 28, 2024 10:07pm | #27

   Hello, would love to see if I could consult with you on my current build. Gladly would hire you for an hour consult.

   Email is [email protected]

2. 
   RobKress | Oct 24, 2003 02:52am | #14

   Gabe,

   Instead of just bashing, why don't you educate us then.  I am not an expert on insulation systems and so far, Paul has been the only one to chime in.  And I appreciate him taking his time to do so and share his knowledge.  If you do know of the better way, why not share.  I do actually need to inuslate my house and am looking for the "right" solution.

   Rob Kress

1. 
   AXE | Oct 24, 2003 03:08am | #15

   FWIW, my local urethane spray foam guy tells me I need 2" to make a vapor barrier.  I have some reservations about the spray + batt method so I think I'm just gonna let the guy spray full depth to get me the sort-of-ridiculous R Value I need.  Sure it will cost maybe $10k to do my addition and my basement rim joists, but in all the years I plan to live here who really cares.

   MERC

2. 
   Gabe | Oct 24, 2003 03:51am | #16

   Part of spray foams ability to act as a vb comes from the skins formed during the spray. There's a skin that forms on contact and one that forms on the top of the layer.

   A good applicator will try to install the foam in several layers to increase on the number of skins formed.

   The absolute minimum installation in ideal conditions is 38mm or about an inch and a half. If you have higher humidity level than the average, you must increase the minimum installation to 50 mm or about 2 inches. That's for minimums. Do you want to insulate to absolute minimums allowed by the factory or do you want to install to their recommendations?

   The next issue is strenght of the assembly. A thin layer sprayed over a medium substrate will have the tendency to crack under wind loads. You have to appreciate that even behind a brick veneer, the exterior walls are subjected to wind loads that will flex sheating. Obviously, a thin layer of foam will crack or fail much easier than a thicker one.

   Cost of installation is another consideration. The costs of having the equipment and installer to site to spray 1 inch as opposed to 3 inches in not 3 times cheaper so not only is it not cost effective it's actually a waste of money. You have an installation that does not perform to the level required with either products.

   Bottom line. An inch of sprayed foam will not meet the most basic of criteria for air or vapour barriers in most applications.

   What pysses me off is self proclaimed experts who armed with a little information try to give others advice and are simply too lazy to properly research the issue. So you'll have to excuse me if I have little patience for "experts".

   Gabe

1. 
   RobKress | Oct 24, 2003 01:55pm | #20

   Thanks for the info Gabe

3. 
   fortdh | Oct 24, 2003 06:53am | #18

   Gabe, you don't"let" me any thing.

   You are free to express your comments the same as anyone else.

   I will continue to give people like Rob the best info I can.

   Paul

   Energy Consultant and author of Practical Energy Cost Reduction for the Home
1. 
   Gabe | Oct 24, 2003 12:46pm | #19

   I will continue to give people like Rob the best info I can. Paul

    

   Energy Consultant and author of Practical Energy Cost Reduction for the Home.

   What a crock of crap. What you want to do is promote your book. You copied a little information from other sources into a book and claim to be an expert. Truth is that anyone who does have experience in the field knows you have no real knowledge in the field of building envelopes.

   Fools like you who try to take advantage of others I have no respect for. You have no real understanding of our industry and are too lazy to pay your dues and learn your craft first.

   You may fool a few but most will know you repeat BS like a parrot.

   Gabe

   Edited 10/24/2003 5:59:06 AM ET by GABE_MARTEL

2. 
   RobKress | Oct 26, 2003 02:41pm | #25

   Thanks everyone for the info and advice.  I am still doing some more research on the topic and will let you know what I come up with.  Meanwhile, the house still moves forward (although a lot slower now cause we have nothing but rain here in Cleveland now)

   Rob Kress

4. 
   Rick_Lawson | Mar 14, 2024 11:22pm | #26

   As for the spray foam, yeah, there are a few types out there. Best bet is to check with your local suppliers or even hit up some forums for recommendations. And about when to spray it in, I'd say do it before the mechanicals go in, gives you a clean slate to work with.