New Hampshire wall assembly option help
Okay so I’m trying to make up my mind on which wall enclosure tech to use.
This house build is in rural Southwestern New Hampshire. 1500sq ft. 2 story, 2 bedroom, no basement. Site is south-facing Hillside. House will be on the north edge of a 2 acre clearing. Site has really good exposure for PV panels. There is currently another house on the site that I built 4 years ago that is using the persist wall system and heated with firewood only until about a month ago when I finally got around to installing a Mitsubishi hyper Heat. I’m really loving the unit for its stable temps, quiet operation and its ability to modulate down because this time of year has been tricky for me historically trying to only put out a small amount of heat from a wood stove. The town I live in allows 2 dwellings on a site as long as you have enough acreage per dwelling. The existing house is in a totally different section of the site. Firewood collection is already part of my life for the existing house and shop.
Wall enclosure option 1:
Double stud wall, dense pack cellulose. I like this wall for its relative ease for traditional framers to build and for it’s lack of use of foam for environmental and ants reasons. Also because I like dense pack cellulose in theory as an insulation material. Total thickness of this wall I’m not certain on yet because of the law of diminishing returns on extreme insulation levels. As well as the cold sheathing/OSB issue. Although my reading on that now has been showing it not as big of an issue as some people once thought it to be, especially if you just choose a different sheathing other than OSB. I would probably go with plywood in this wall set up. This wall design is also relatively easy for window and door installation as well as other accessories and not terrible for all the sub trades.
Option 2 is the PERSIST wall:
I like this wall because of its easy air sealing and protection of the structure from rot and because I have already built a house with this system so I know what to expect. Downfalls of the system are the need to use rigid foam board for environmental reasons, Ants (I currently battle those in my existing house. Although it’s not a terrible issue at least that I know of yet) COST.
Wrapping a house in foam makes anything attached to the outside a tricky endeavor, ask me how I know LOL.
Foam options probably Iand in this order from my perspective:
Eps- although I have not found a local source this yet
Recycled polyiso foam- this is what my current house is wrapped in. Takes extra labor to work with and from what I am told has a reduced R-value due to age.
Virgin polyiso foam
Xps- too environmentally bad for me to use
Wall option 3:
2×6 wall dense pack cellulose with really good air sealing details. Possibly doing the BONFIG wall approach with this system. This wall is obviously not super insulated but with this building approach the money is instead spent on PV panels to offset the lack insulation with air source heat pumps. The more I research high R value wall systems and there down falls the most I think about this system.
I am anti any crazy wall systems including wacko I-joist stud walls and whatnot. LOL. Also I am not a fan of SIP panels
No matter what wall system is decided on this house will have a PV array. But any budget money not spent on insulation will go directly to the PV array size.
Another factor that I keep thinking about but maybe I am overly romantic about it is the desire for me to have a wood stove in this house. Partially because that’s what people do around here, partially because we lose power enough to like the security of a wood stove, partially because I have a woodlot, partially because there is nothing like sitting next to a wood stove mid-February while it’s dumping snow outside.
All that said I know first-hand how hard it is to have a wood stove in a small, well air sealed house. Draft issues, air quality issues, wood stove protrusions creating air leaks ect.
I think in my perfect world this house would be built with fairly conventional materials (easily sourced locally), use dense pack cellulose, avoid rigid foam board except for the foundation, run annually net zero from the use of a large PV array, air source heat pumps, HRV and supplemented with a small efficient wood stove. And be not so costly to build that I have to lie to the local climate change denier types LOL
So in summary I guess there are two questions here:
1- Given these site details what wall system would you choose?
2- Should I or should I not include a wood stove and how does that affect the wall system choice?