DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (http://www.diychatroom.com/)
-   Insulation (http://www.diychatroom.com/f103/)
-   -   Spray Foam vs. Fiberglass, anyone done the math? (http://www.diychatroom.com/f103/spray-foam-vs-fiberglass-anyone-done-math-132888/)

vtboy51 02-07-2012 09:13 AM

Spray Foam vs. Fiberglass, anyone done the math?
 
I'm building roughly a 2000sq ft home in Vermont, is it worth the extra cost to spray foam the walls vs. fiberglass? How many years roughly to recoup the cost of spray foam?

hammerlane 02-07-2012 11:10 AM

What kind of costs are you getting for each?

Cost for fiberglass batt about $800??

Cost for spray foam about $6000??

Am I close?

AGWhitehouse 02-07-2012 11:17 AM

If you are planning on being alive long enough or are going to pass this house down to your kids, I'd stay away from spray foam unless you're doing a flash/batt method. When it comes time to renovate/upgrade that structure, spray foam will only add significant $$...You can't snake, you have to demo. So you'll pay more now and pay more later for a full foam install while flash/batt system will give you the sealing quality at a cheaper price and allow for renovations, etc. in the future.

vtboy51 02-07-2012 11:27 AM

I haven't even gotten that far, I just figured someone has already done some rough homework on the extra cost and what the heating cost benefits are.

Quote:

Originally Posted by hammerlane (Post 846833)
What kind of costs are you getting for each?

Cost for fiberglass batt about $800??

Cost for spray foam about $6000??

Am I close?


AGWhitehouse 02-07-2012 11:32 AM

The talk around the water cooler is that foam is, on average, 3x the cost of fiberglass...

There is more to consider on all this than just what type of insulation. Foam creates an air-tight seal that is not found in "traditionally" built homes. When you seal a house that tight, you now need to introduce mechanical ventilation to achieve the code required air changes and eliminate the risk of "sick house syndrome". These are costs that go above an beyond the additional insulation costs. Not taking into account the air change requirements, could lead to increased health risks and bouts of common illnesses due to airborn pathogens and debris that is not being filtered or exchanged.

The "traditional" home design accommodated the required air exchanges via leaky walls, windows, and doors. You turn on the kit/bath exhaust and it pulled in air through all the cracks. If you seal all those cracks and get nice tight doors/windows, you'll need to provide a source for fresh air intake.

jklingel 02-07-2012 11:47 AM

As stated, foam is expensive; over 3x what cellulose would have cost me. On top of that, the environmental impact is significant. If you want to use batts, I would suggest you consider leaving the fiberglass at the store, and get Roxul or one of the other batt products. FG is lowest on the list for overall R value. Too, consider a double stud wall with dense packed cellulose; one of the cheapest, $/R, and most environmentally positive ways to build. And DO build tight, then get an HRV.

AGWhitehouse 02-07-2012 11:59 AM

Quote:

Originally Posted by jklingel (Post 846863)
And DO build tight, then get an HRV.

Thanks for clarifying. I do agree and also recommend building tight and providing mechanical means of ventilation. The initial cost is quickly paid back through operational efficiency.

hammerlane 02-07-2012 12:06 PM

Quote:

Originally Posted by vtboy51 (Post 846848)
I just figured someone has already done some rough homework on the extra cost and what the heating cost benefits are.

Very hard to calculate with a degree of scientific certainty the cost benefit of when you would recoup the spray foam money.

To do this you would need two identical homes..well almost identical except one has spray foam and one has fiberglass insulation. Home would need to be situated in the same geographic orientation to take advantage of the sun's orientation.

Then you could calculate energy usage on each.

jklingel 02-07-2012 01:13 PM

Quote:

Originally Posted by AGWhitehouse (Post 846871)
Thanks for clarifying. I do agree and also recommend building tight and providing mechanical means of ventilation. The initial cost is quickly paid back through operational efficiency.

Roger that. One thing that surprised me is how "cheap" it is to provide fresh air. Ignoring the trivial cost of the HRV (:laughing:), it was only going to cost me a few hundred bucks in heat loss to operate it. I have no idea how that compares to what a leaky house costs you, but it made it clear that the HRV was really not a huge difference, and then you get the air moved properly, etc. I think the "build it tight, ventilate right" mantra is a good deal. I hope so, 'cause I'm gonna spend the $$ on one soon.....

AGWhitehouse 02-07-2012 01:40 PM

That is going to be the future of building when the new energy codes kick in. My uncle is building an "experiment house" and is purchasing HRV's he says have a 95% efficiency rating and only require 1A to operate. He said he was going to get me the cuts, but if he wasn't exagerating, those are some awesome performance specs. I can't imagine a leaky house is better than that considering the added benefit of actually filtered air exchanges.

NEFoamer 02-07-2012 03:27 PM

Quote:

Originally Posted by vtboy51 (Post 846848)
I haven't even gotten that far, I just figured someone has already done some rough homework on the extra cost and what the heating cost benefits are.

It's generally going to cost around 3x more for closed cell insulation, which is what you would want in vermont. I would NOT recommend flash and batt to anybody unless you're spraying at least 2" of closed cell, and at that point you might as well add the 3rd inch. The average payback is generally going to be around 7-10 years, but that is largely going to depend on your initial costs, heating costs, and future heating costs. You'll generally save 40%-50% on heating and cooling costs. You can usually also reduce the size of HVAC equipment, which can offset some of the cost of an HRV.

NEFoamer 02-07-2012 03:34 PM

Here is one case study, I'm sure you can find some more out there, hopefully more specific to your location.

http://advancedinsulationla.com/casestudy.pdf

hammerlane 02-07-2012 03:40 PM

Quote:

Originally Posted by NEFoamer (Post 847021)
You'll generally save 40%-50% on heating and cooling costs.

I think that comment is such a crock and a common "talking point" in the window and insulation industry. I wonder how many companies would back that up with a guarantee to pay anything over a 3 year average of your gas bill in the winter.

hammerlane 02-07-2012 03:43 PM

Quote:

Originally Posted by NEFoamer (Post 847028)
Here is one case study, I'm sure you can find some more out there, hopefully more specific to your location.

http://advancedinsulationla.com/casestudy.pdf


Interesting reading

NEFoamer 02-07-2012 03:49 PM

Quote:

Originally Posted by hammerlane (Post 847035)
I think that comment is such a crock and a common "talking point" in the window and insulation industry. I wonder how many companies would back that up with a guarantee to pay anything over a 3 year average of your gas bill in the winter.

Feel free to google richard rue and energywise. Former nasa scientist who developed a program to do just that.


All times are GMT -5. The time now is 03:46 AM.


Copyright 2003-2014 Escalate Media LP. All Rights Reserved