I'm in the middle of an addition of my existing home and it's basically a gut and could almost be considered new construction by the time we are done.  Anyway I have a few quotes and foam is all over the place - if I could get some feedback I'd appreciate it


I live in Southern New Jersey - FYI
Please keep in mind I am constructing a 2 story house and have the 2nd floor hvac unit, duct, & pot lights in the ceilings



Quote 1 -

1" CC SPF in walls ( $1500) - combined with batt insulation  - ( $1232 )

R38 on attic floor - $1200

no basement  / crawlspace in quote -

TOTAL PRICE - $3932


Quote #2 -

10" open cell in attic - $12,500

3" closed cell on walls of basement, crawl, 1st & 2nd floor. - $15,000

Total PRICE - $27500

Quote #3 -

2.5" CC in attic

2" CC on  basement / crawl, 1st floor, & 2nd floor exterior walls

TOTAL PRICE - $6875




As you can see the quotes are all over the place!



Quote #1 does not like foam, but will flash my exterior walls - he said to get he required R value I'd need another $9,000 to foam the attic the way I want

Quote #2 - I have no idea !! - the same principal with 10" of foam on roof

Quote #3 came with a letter stating the equavilent R value of 2" of foam is R40 and if the building inspector approves it they would do it - they said they have done it in the past.

Quote #3 came from my energy auditor, who conducted my blower door test ( 1080 sq ft house built in 1890 that went 7000 cfm!)  he also said quote #2 was sub contracting it out, so thats why it might be so high

any ideas ? any suggestions? Any questions I should pose to these guys?

Anyone have any comment on this document? I found a similar one online here:

www.alpinefoam.net/pdfs/USDeptofEnergy.pdf

Why do you want to go spray foam?

You are talking about a 1080 sqft home, which is very small. Spending $27k to insulate it is completely insane.

Why not go with blown in dense cellulose? It's cheaper and performs very well.

Do you have any pictures of the home and remodel?

I agree. You will NEVER see that money back in savings, ever. I would consider possibly foaming the roof if you need the hvac up there, but then since the exterior walls are open, you can caulk and seal it up then go in with netted and blown instulated. BTW- I sure hope your energy auditor wasnt the one that said 2" of CC equals r40. r value is r value...they (insulating contractors) like to add in numbers for air sealing abilities to claim much higher r values. What is interesting is "if your inspector will allow it". Then means its a violation and does not meet IECC. Around here, 2" of cc is equal too....r12-14 depending on foam brand.

sorry for the confusion - original home is 1080 sq ft - with additions and second story added it will be almost 2500

I want foam for the air sealing, and tightness,. we have had a leaky house ( $500 electric bills for ac inthe summer ) and oil heat -

we want foam and geothermal - we have been beaten up hard on the utilities and we have a chance to fight back

Posted By DJV on 24 Sep 2012 09:15 PM
sorry for the confusion - original home is 1080 sq ft - with additions and second story added it will be almost 2500

I want foam for the air sealing, and tightness,. we have had a leaky house ( $500 electric bills for ac inthe summer ) and oil heat -

we want foam and geothermal - we have been beaten up hard on the utilities and we have a chance to fight back

I'm confused. So you had a 1-story, 1080sqft home that was built in 1890 and you expanded it to a 2-story that is now 2500sqft?

Why wouldn't you just demolish the thing and build from scratch? Since you added a 2nd level and additions, you didn't keep the historic integrity of the building anyway.

It's always easier, more cost effective and nets better energy results starting new than trying to fix something that is old. With that being said, if the building is not tight and leaky, you don't want spray foam because water can get on the wood and foam and begin to rot the wood away. It will also release the bond that the spray foam had and it will all become one big mess.

Best bet is to seal the home properly by addressing the exterior sheathing & taping, waterproofing, applying 1-2 inches EPS/XPS, taping and then siding/stucco. If the outside is WATER TIGHT, then inside you can do cellulose in-between the framing members. AS LONG as you keep the cellulose DRY, it will help prevent air leaks if densely packed. Cellulose is not meant to stop water leaks, if it gets wet it loses its R-Value and can cause it to decay & lose its flame retardant chemicals.

Post some pics so we can get a better idea what you are dealing with...

i'll try and post pix -
just got the roof off last night

Do the math on the board-feet (square feet of covered area x inches of thickness). Closed cell foam would normally come in between $1/bd-foot (for high volume jobs) to $1.20/bd-ft (flash'n'batt, etc). Open cell should come in between 30-40cents/bd ft.

Without knowing the area x R I have no way of telling whether those quotes are over the top or right in-there.

On a full-gut rebuild it's generally cheaper to air-seal with flash-foam the interior and fill out the rest in fiber, THEN apply the cost savings toward exterior foam insuolation between the sheathing and siding. If you're going with exterior rigid foam it's sometimes cheaper to go with open cell cavity-fill rather than a flash + fiber. Batt insulation is OK if it's sufficiently high density and installed perfectly, but with no-standard stud spacings on the antique "perfect" becomes impossible. After a flash-foam air seal either wet-sprayed cellulose or dense-packed (3.2lbs/cu.ft. min) cellulose would be fine in NJ, with even an inch of exterior foam (any type) on 2x4 or 2x6 studs, but 1.5"+ (~R10) of foil-faced polyiso or 2"+ of EPS would be better. Alternatively, high-density (1.8lbs/cu.ft min) fiberglass could be used, but it's usually more expensive.

To minimize the thermal bridging of fasteners on exterior foam and to not compromise the air-tightness it needs to be held in place with furring that is through-screwed 24' o.c. to the structural studs with pancake-head timber screws (FastenMaster HeadLok or similar.) The R-value of the foam between the studs is wasted by the thermal bridging of the framing, whereas if you do it right you get pretty much full R value out of exterior foam, so save the foam budget for the exterior.

See: http://www.greenbuildingadvisor.com/blogs/dept/musings/how-install-rigid-foam-sheathing

On the roof it may be cheaper to use rigid foam on the exterior (thermally breaking the rafters) and less open-cell on the interior. With 10" of o.c. foam on the interior it is still vapor-permeable enough to end up with high end-of-winter moisture levels in the roof deck, but in a NJ climate with R15+ on the exterior the roof deck stays sufficiently above the interior dew point that it won't rot out with only open-cell or cellulose on the interior. While closed cell is a better air-sealer in general, at 3"+ open cell does a pretty good job. But no air sealing job is complete without testing- preferably BEFORE the finish wall gypsum is up, while it's still possible to rectifiy cheaply.

If insulating at the attic floor, air-seal first, and vent the roof with soffit venting that is ~50% bigger in cross section than the ridge venting (to prevent excessive stack effect drives on the conditioned space air.) In attic floor apps cellulose will outperform any low-density fiberglass solution at the temperature extremes. (High density batts could come close, if installed "perfectly", but is more expensive per unit-R.)

On stone basements 2"(R12) of closed cell foam would be enough, 3" would make some sort of sense if you're going for a higher-R home. But at 3" the greenhouse gas potential of that final inch is greater than the energy savings it offsets over it's lifecycle unless you're going with a water-blown product. The only closed cell foam I know of that isn't blown with HFCs is Icynene MD-R-200, which runs about R15 @ 3", which is fine. Most HFC blown goods would run R18-19 @ 3", but R12-13 @ 2", and stopping at 2" would be fine.

In a US climate-zone-4 NJ climate going with ductless air-source heat pumps is about as efficient as geothermal at a fraction of the cost, but only works from a room-to-room temperature balance if you go with better than code R (like 2" of exterior foam), and somewhat better than code windows and keeping the size of the windows in any doored-off room pretty bounded. With 3" of exterior foam and U0.25 windows you could get away with one ductless-head per floor. It's highly likely that with air-sealing, better windows and even code-min R values the heat load would be under 3 tons, and may be under 2.5 tons. With a bit more R and lower U that it would take to keep room to room temperature differences bounded you're probably looking at under 2 tons, which would be a CHEAP ductless solution, with a more expensive wall/window/roof-R package, but higher comfort overall. It takes a sharp pencil to figure out the best bang/buck on any of it, but with NJ's heavy subsidy of residential photovoltatic panels there may be an argument for including that in the total R/U-values vs. geo/ductless accounting. My strong bias is toward spending the money on higher performance building envelopes rather than higher performance mechanical systems, and the difference in efficiency between a cheap ductless and a very expensive geo system just isn't there, if the ductless can actually fill the bill. (I have relatives living in marine US zone 4b heating with single head mini-splits in houses with sub-code R who are more than satisfied with them, and prefer them to ducted-air of any type.)

Don't fall for the marketing hype of insulation manufacturers- all of them say their own stuff is great and other stuff is junk. It's all good when correctly applied ('ceptin' for low density fiberglass in any application other than for zone-isolation under radiant floors.) If you keep fiber insulation above the dew point of the cavity air and it's at a density with sufficient air retardency, installed with no gaps or voids, it's pretty cheap & effective. In NJ it doesn't take much exterior foam to meet the dew-point standard, but even more is still cost effective against long-term energy use, or when trading off geo against air-source costs & efficiencies. A code-min 2x6 studwall with no exterior foam comes in at R13 after factoring in the thermal bridging of the studs. But a 2x4 fiber-insulated wall with 2" of exterior foam comes in at ~R20, and keeps both the sheathing and any fiber insulation in the wall cavity above the dew point of the interior air, and you don't need (and shouldn't use) interior side vapor retarders stronger than standard latex paint. A 2x4 wall with 2" of exterior polyiso is about R22, and is the same thickness as the R13 2x6 wall. Filling the 2x6 wall with a full 5.5" R7/inch foam comes in at about R16, with a typical 25% framing fraction, at several times the cost of a flash-foam + fiber + exterior rigid foam or o.c. cavity fill/exterior rigid foam 2x4 solution.