Insullation and Geothermal Help Needed

[crash11]

Hey guys, I'm new to the forum. I'm planning on building a house this summer, and I'm racking my brain everyday trying to figure out what insullation and geothermal package to use. Here's some stats on the house:

1 - 2500 sqft cape cod with cathedral ceiling living room
2 - Basement (28 x 60 ft) will be walkout with Nudura foam (2" thick) inside and out
3 - 2x4 exterior walls
4 - Southern michigan
5 - I will have a 100 cfm air-to-air exchanger

My builder has presented me with two options for insullation, baton or cellulose. He guessed that the cellulose would be about $6,000 more than the baton. Also, I'm wondering what size Geothermal unit to get. Should I go for 3, 3.5, or 4 ton unit? Is it a good idea to get a variable speed fan or will a 3 speed fan do ok? Is R410A worth it? Any feedback is appreciated. please let me know if you need more info. Thanks.

[tuccillo]

Originally posted by crash11
Hey guys, I'm new to the forum. I'm planning on building a house this summer, and I'm racking my brain everyday trying to figure out what insullation and geothermal package to use. Here's some stats on the house:

1 - 2500 sqft cape cod with cathedral ceiling living room
2 - Basement (28 x 60 ft) will be walkout with Nudura foam (2" thick) inside and out
3 - 2x4 exterior walls
4 - Southern michigan
5 - I will have a 100 cfm air-to-air exchanger

My builder has presented me with two options for insullation, baton or cellulose. He guessed that the cellulose would be about $6,000 more than the baton. Also, I'm wondering what size Geothermal unit to get. Should I go for 3, 3.5, or 4 ton unit? Is it a good idea to get a variable speed fan or will a 3 speed fan do ok? Is R410A worth it? Any feedback is appreciated. please let me know if you need more info. Thanks.


Why not do the whole house with ICF instead of just the basement? If you decide to stay with 2x4 framed construction, take a look at spray foam insulation in the walls instead of cellulose or batts. Also, take a look at using roof sheathing with a built in radiant barrier - it will reduce your attic temperatures. You could also take a look at spray foam insulation on the underside of your roof sheating - not sure about the cold climate aspects - I used it on my house in south GA.

[mfree]

How well does the spray work on the inside of the sheathing? I have an uninsulated attic with maybe 6" of fiberglass on the interior roof and I can tell it's a bit of a temperature leak...

[crash11]

Is a spray foam insullation relatively cheap? My gut tells me R-13 baton just won't be enough, even if we go to R-39 in the attic. However, that cellulose option seems too much (mostly in price). I'm trying to keep the costs extremely low right now, as my income isn't nearly as good right now as it will be in about 3 years. I'm going cheap on the carpet, flooring, doors, trim, etc because i know I can change all of that myself in the future. Insullation can't be changed. Not easily anyway, but that doesn't mean I am prepared to drop $6,000 into it.

[tuccillo]

Originally posted by crash11
Is a spray foam insullation relatively cheap? My gut tells me R-13 baton just won't be enough, even if we go to R-39 in the attic. However, that cellulose option seems too much (mostly in price). I'm trying to keep the costs extremely low right now, as my income isn't nearly as good right now as it will be in about 3 years. I'm going cheap on the carpet, flooring, doors, trim, etc because i know I can change all of that myself in the future. Insullation can't be changed. Not easily anyway, but that doesn't mean I am prepared to drop $6,000 into it.

Spray foam ( closed cell ) can be expensive - figure about $1.50 per square foot. R-7 per inch but that doesnt tell the whole story - air infiltration is reduced to zero. It is typically sprayed on at about 2-3 inches for both wall cavities and on the underside of the roof sheathing. We used it in our ICF house on the underside of the roof sheathing. We are moving into the house in 1 week so I dont have any specific experiences yet but some folks I know who have also used it claim their attic stays very cool. You may get by with a smaller furnace/heatpump/AC with the better insulation to help offset the costs.

[BobbyBJr]

I have a friend that sprays that insulation and it does work. He sprayed the underside of his roof about two years about and I was up in his attic in the dead of summer and it was downright amazing how cool it was up there. I thought he was cooling the attic until I looked up and seen the stuff. Now, it is pricey for sure to have it sprayed, but I'm thinking in the long run, it might be worth it. I quoted a job a couple months ago where the owner was considering using the foam. It made a tremendous difference in the load calcs, so we could use smaller equipment that would cost less up front and less to operate too. The downside was that the price to do the entire house was about $12,000. The owner finally decided to just do certain areas of the house with the foam and use batts in the rest of it. It will be interesting to see how his plan works out.

Bobby

[tuccillo]

Originally posted by BobbyBJr
I have a friend that sprays that insulation and it does work. He sprayed the underside of his roof about two years about and I was up in his attic in the dead of summer and it was downright amazing how cool it was up there. I thought he was cooling the attic until I looked up and seen the stuff. Now, it is pricey for sure to have it sprayed, but I'm thinking in the long run, it might be worth it. I quoted a job a couple months ago where the owner was considering using the foam. It made a tremendous difference in the load calcs, so we could use smaller equipment that would cost less up front and less to operate too. The downside was that the price to do the entire house was about $12,000. The owner finally decided to just do certain areas of the house with the foam and use batts in the rest of it. It will be interesting to see how his plan works out.

Bobby

The heatload/heatloss calculation for our house with the ICF and sprayfoam insulation on the roof sheathing was not straightforward. Eventually, the HVAC guy and I came up with the same number ( I used HVAC calc and he used some other package, dont recall the name ). I didnt see much sensitivity to the choice of insulation with HVAC calc - once you had a high amount of insulation( say assuming R30 ), the numbers didnt change much by varying the insulation - I didnt really know what value to use or whether to include the attic space in the calculation. I came up with 3 tons for 3000 sq feet - in talking to others who have worked on an ICF house with sprayfoam, this seems to be a reasonable number. We will find out soon as we are getting ready to move in and summer is just around the corner.