Building a superinsulated home has always been of interest to me, but given the status of the housing market these days my wife and I have abandoned our plans of building a new home and instead are planning to stay long term in our existing home. We are in NJ and have a 2 bedroom, 1 bath ranch on a full basement that was built in the late '60s. There is fiberglass in the walls and attic, but I'm sure that even for the time it was the bare minimum. The fiberglass in the ceiling is barely 6" thick. I plan to address this with blown in cellulose after taking care of air leakage into the attic. It should cost me about $1000 doing it myself (free 24 HR blower rental from Lowes with purchase of cellulose) to get to R-60. The walls however, are another story. We have vinyl siding that is faded and dated, so we could definitely go for an updated exterior. There is just tar paper vapor barrier underneath and I believe there is a fiberboard product like Homasote underneath of that. I would want to do a complete tear off, foam all windows, doors, and any other openings from the outside, and then cover with Tyvek Housewrap. Beyond that I'm lost. I've looked at the various rigid foam boards on the market but never seen them used-can someone point me to a good forum/blog about adding rigid foam to the exterior of an existing home? I'm assuming that whatever I end up going with, the siding nails will have to be long enough to penetrate through the foam into the sheathing, correct? It is even possible to install siding this way? We are thinking of going with Hardi-plank.