I'm in the process of building a house in Central NJ. In climate zone 4a not far from 5a.  Brick front, vinyl sided Wood framed 2 story 3000sf living space with a vented unfinished attic (currently un-vented but subject to change). All areas that are sided have 1/2" insulation on the exterior Radiant heat throughout and 2 zone A/C for living space.  All duct work is in the attic.

When this project started I didn't give much thought to the building envelope.  I was going to build in a traditional manner with batt insulation and so on.  As the project continues, I'm intrigued by the different technologies that create a more efficient and environmentally friendly structure.  If I had done my homework before this process began I would have been able to plan better and change the house accordingly.

I'm approaching the time to decide on the type of insulation and whether to change the attic from vented to un-vented.

As the building progresses I have been doing my best to building a tight structure by sealing the penetrations, foaming/caulking windows, chalking exterior corners and T-walls.

My budget like the price of batt-insulation.

CC Spray foam for the whole house is out of the budget.

OC spray might be a possibility for the whole house but it's still a little out of reach at this time.

I was thinking of going with a hybrid system but wasn't sure which is better foaming the attic and batts for the walls or visa-verse and how much foam

I like the idea of foaming the attic rafters so that the HVAC system won't have to work so hard.

My questions:
Given my house has a brick front and 1/2" insulation on the exterior where there is siding, will it leak excessively?  Is it already sealed more than a normal house?

What's the best approach for the insulation? If foam how thick?

Should I create an unvented attic especially since the entire HVAC system is in the attic?  Would doing so translate into an appreciable energy savings

What do I have to watch out for? (the chain reactions of extras that occur from choosing one way over the standard batt)

How do I determine if I need an ERV and how are they sized?

Vapor barriers in what instance do I need them and where should they be located?

I have not looked into blown cellulose is that something that I should do?


My concerns:

My family's  health and safety (both from a ventilation and fire stand point) One spray foam installer told me I would have to sheet rock my attic, which is one of those hidden extras.  the other two quotes I recieved didn't mention I would need to do that and my building inspector would not require it unless the manufacturer of the foam required it.

Moisture, mold, mildew problems that I create by varying from the standard building approach.

High utility bills

My building budget.  I will sacrifice finish items to create a more efficient home but I really need to stay within the budget so that I can actually finish this project.

Any insight you can offer would be greatly appreciated.

Thank you

I am an insulation contractor in Central NJ.  We work with fiberglass, cellulose and spray foam insulation and have been in business for many years.

With every job we do, we always do the prep work which includes sealing the horizontal penetrations, foaming/caulking windows, sills, T-walls and corners - we seal it all up.

Not all attics have to be sheetrocked, there are differences as to whether it is a closed attic assembly or not.

If you like I could have one of my guys come out there for you, get your questions answered, and even measure your house and give you a proposal.  Estimates are free.

We do fiberglass and foam insulation so we can provide a price on each or a hybrid situation as you are talking about.

Feel free to call if you like - my number is 732-955-8420 and we can set something up for you.

aronis thanks for the offer. I've been in contact with someone from you company.