Foam or Fiberglass

[mfreed]

I'm building a home in SE PA. I'm very interested in Foam insulation but I have never seen it used in this area.

I've heard it costs more than Fiberglass. Can anyone provide any guidance on how much more it costs on a per/sf basis? The house will be 3650SF finished space.

Also - 2x6 exterior walls so I'm looking at R19 batts for the fiber.

[BrianL]

I had it installed in my attic (about 400 sf) and paid either $2 or 3K for it. Very satisfied with it and its definitely keeping my attic cooler in the summer and warmer in the winter. If I went with fiberglass, the most R value I could of gotten was R15, but I have the equivalent of R30 or better now.

BTW- I live in Abington so I'm probably in your general area.

[David]

400sf ? Was that a typo?

[BrianL]

400sf ? Was that a typo?

Yeah- more like 500+ sf.

[David]

Wow. That's really expensive!

[ThomasB]

Yeah- more like 500+ sf.

Did you use closed cell or open cell? How many inches thick was it applied?

[BrianL]

Did you use closed cell or open cell? How many inches thick was it applied?

Closed cell applied to a depth of 3-4 inches between the rafters and about 5-6 inches at the gable ends.

Just heard back from the wife- we paid $2100 for it.

[natemclain]

I had open cell foam sprayed in my addition on the 3 exterior walls (640sf wall area, 26'x27' addition). It was 2x4 exterior walls and they filled the entire cavity. My bill was $1,020. It definately eliminates any draft and it is very quiet. I'm getting ready to foam my entire attic using open cell foam on the decking. I have a very close friend that bought a foam machine a couple years ago so I just have to pay for the material on this next job. I will have a little over $2,300 in all the foam for my entire attic (27'x75' House with gable ends on a 5/12 pitch). I'm excited to see if it will help with my utilities.

Just thought I would share.

Nate

[Owner Builder]

Spray foam is definately more expensive than fiberglass, but well worth the additional costs in the long run. Another option would be sprayed in Nu-wool cellulose in the walls. The costs are more than fiberglass, but less than spray foam.

I plan on using spray foam when I finish my basement. I have a Superior Walls foundation, so I can fill between the concrete studs with about 2-3 inches of foam. Also plan on removing the fiberglass batts in the bond and spray foaming that at the same time. I think this will make a good winter project.

[dieselman66]

hay i could be wrong but some foam even rigid is not bug proof make sure you find out better safe than sorry

[John_S]

it is not bug proof, but it contains nothing that would attract bugs to it, it is chemically dead.

Also it is very typical the costs of spray foam is at least twice the cost of standard methods. Be careful of someone trying to apply more than two inches of closed cell foam, it does not yield results that warrant the cost when applied too thick.

Lastly it is not all about R-value, R-value and foam don't really add up like R-value and fiberglass do.

[John_S]

Just something I wanted to mention, if anyone was ever curious about getting into the spray foam business. Checkout the foam equipment and types of spray foam rigs out there. The industry is a unique, small and widely supported industry from the President himself.

[concretemasonry]

Any insulation between studs will never give the same R-value for the wall as the insulation. The wall insulation will be 15% to 40% lower (depending on the stud material and spacing) than the R=value of the cavity insulation and will never match the R-value of a solid foam material applied continuously.

Dick

[bighammer]

Personally I would spray 1" of foam tight against the sheathing for the sidewalls and than blow the rest with cellulose. In the attic I would blow 18"-20" cellulose with ofcourse proper ventilation - what is the budget - fiberglass is cheap and has proven a good insulation

[dmat]

Building "Net zero house", quotes acknowledging that this is experiment. Planning to use spray foam, open cell, walls and ceiling, filling 2x6 and 2x8 walls that have 2" of styrofoam outside the sheathing under efis stucco, 8 inches in ceiling. My plumber and electrician may have been busting my you-knows, but were talking about some problems with spray foam making pex and//or wiring brittle. Anybody aware of this?

[AaronB.]

it is not bug proof, but it contains nothing that would attract bugs to it, it is chemically dead.

Also it is very typical the costs of spray foam is at least twice the cost of standard methods. Be careful of someone trying to apply more than two inches of closed cell foam, it does not yield results that warrant the cost when applied too thick.

Lastly it is not all about R-value, R-value and foam don't really add up like R-value and fiberglass do.

I do foam. Closed cell foam is about R-7 aged per inch. We must keep in mind that R value is a theorhetical number that cannot be truly achieved, or even analyzed until you decifer K value.

Now... 4 inches of closed cell foam is about that is worth buying. Any more than that does no better for insulating purposes. The 1st inch stops 85%, the 2nd inch stops 85% of the remaining 15%, the third inch stops 85% of the remaining 2.25%, and the fourth stops all but 1/3 of 1% of the original thermal value.

SO... dont buy more than 4 inches of closed cell foam. You would be wasting your money...

Now as far as cost...

.5# density open cell will yield about 15,000 board feet per 110 gallon drum set, and still provide only R-3.5 per inch, generally speaking, and is no better than fiberglass, except for the fact that it stops drafts.

1.75# closed cell will get ya about 4500 board feet per set. BUT with double the r per inch, you dont need but 4Inches to gain maximum value.

My roofing foam is 3#, very dense, and I get much less yield with the roofing grade stuff.

Im about a buck a board foot for closed cell. This is the maximum I recommend for interior insulation purposes.

For roofing, you may need to go thicker if you have standing water. Also, with roofing, you have a roof and ceiling insulation in one... and if done properly, you wont have to ever replace, just maintain this roof.

[AaronB.]

"About mid 1975 we received a call from a division manager of one of the major fiberglass insulation manufacturers. The caller asked, "I understand that you are spraying polyurethane in the walls of homes?" We told him that was true. He was calling because we were cutting into the fiberglass insulation sales in his area. He asked, "How can we do it?"

We knew what he meant. He wanted to know how we could look somebody in the eye and sell them a more expensive insulation than the cheap old fiberglass. We told him the way we did it is with a spray gun. Of course, that wasn't the answer he wanted. He wanted to know how we could not feel guilty. We told him of insulating one of two nearly identical houses built side by side. We insulated the walls of one with 1.25 inches of urethane. The other house was insulated with full thick fiberglass batts put in place by a reputable installer. Not only did we use only 1.25 inches of urethane as the total wall insulation, but we had the builder leave off the insulated sheathing. At the end of the first winter, the urethane insulated home had a heating bill half of their neighbor's. We know that is not terribly scientific, but it is very real. We're not sure he was convinced, but it should be noted that same company jumped into the urethane spray foam insulation supply business the next year.

One and a quarter inch of polyurethane sprayed properly in the wall of a house will prevent more heat loss than all the fiber insulation that can be crammed in the walls -- even up to an eight inch thickness. Not only does it provide better insulation, but it provides significant additional strength to the house."

This was taken from another website, but pretty much says it...

[Dan the Insulation Man]

I had it installed in my attic (about 400 sf) and paid either $2 or 3K for it. Very satisfied with it and its definitely keeping my attic cooler in the summer and warmer in the winter. If I went with fiberglass, the most R value I could of gotten was R15, but I have the equivalent of R30 or better now.

BTW- I live in Abington so I'm probably in your general area.

I am an insulation contractor fiberglass and foam. People mislead and sometimes lie to customers. I tell them straight out. An open cell foam on average is around 3.7 R-value per inch. R-value and sealing factor does not make R factor higher. It may enhance performance. I know of people LYING and saying 1 inch of foam is like an R40 no one inch of open cell (average manufacture specs) is an R3.7 per inch.
A 2x4 wall fiberglass is max R15 value whether its batts or Blown In Blanket System. (Blown In Blanket is the best Fiberglass method available) Foam on average is around 3 to 3.5 inches so its around R14-15 value but you get a better sealing Factor which enhances the performance of foam. In a 2x6 rafter (stick framed) against roof line. Average foam install is 5-5.5 inches open cell unless you go closed cell which is higher R factor but more expensive per foot. Closed Cell can give you around 7.4 R-value per inch but it costs up to 1.00 or more a foot. So if they if install open cell on the roof line at 5-5.5 inches example you have an R-factor of about R19 give or take. (Most of the time if they install closed cell they don't spray a full 5-5.5) The only advantage is the sealing factor which enhances or causes the foam to work more efficiently. Always remember R-factor is R-Factor and sealing factor DOES NOT increase R-Factor. I install both but I never mislead anyone. :)