In an effort to burn less firewood this winter I started insulating the house this weekend. I am putting up 1" green board then screwing 1/2" concrete backer board over it. I'm screwing into concrete so it is slow going but it is working. The insulated walls are now the indoor temperature while the non insulated walls are the outdoor temperature.
It will work. I added insulation and windows to my house a few years ago. It cut the natural gas bill by $50 to $70 and the peak power bill by 100 dollars plus.
I have never heard of using green board for insulation, seeing it has no dead air space .green board sheet rock is usually used in bathroom walls to resist mold and mildew. If I were doing insulation I'd be putting foil backed foam insulation on the inside of the house . and fiber glass insulation in the celling and floor . dual pane windows and doors. to my understanding it is dead air space that insulates .
You can also glue 1 1/2 inch foam insulation to the walls and then apply a concrete like coating over the foam that provides a hard surface that looks like stucco. This would be less work and get a higher R value for the same thickness. I understand you might be wanting the impact resistance using the backer board and you could stay with that down low but use the higher R value higher up the wall where it helps even more. You can blend the two methods with the coating. Foundation insulation coatings come as a premix in a 5 gal pail or cheaper stuff in a bag to which you add water and mix. They have fiber in them to add tensile strength and there are meshes you use to span the joints so it doesn’t crack there with expansion and contraction. I put two inch foam on the outside of the basement walls of my house with these coatings. You can’t bang the mower into it but if you lightly graze the walls with a weed wacker it doesn’t slice into the foam. I used Tuff Coat II and was very pleased with it. https://www.homedepot.com/p/STYRO-Industries-5-Gal-Foundation-Grey-Tuff-II-Foundation-Coating-TTFG/203009638?cm_mmc=Shopping|G|Base|D22|22-9_CONCRETE|Generic|PLA|71700000033888454|58700003921204977|92700031718658634&gclid=EAIaIQobChMI15jMkqSh3QIVD7nACh0iuA9SEAQYAyABEgLo2PD_BwE&gclsrc=aw.ds&dclid=CNDvlJ-kod0CFQ6_wAod4ksBkg AT
Sorry, I meant that green rigid foam insulation. I forgot about the green board drywall. I bought some of that mesh to span the joints but I was not sure what I was going to do for a coating. I think I have one of those spray hoppers laying around I guess I could spray it over the backer board.
In my ballistic concrete tests I found that putting up a layer of foam over stucco then applying stucco to the new exterior dramatically increased bullet resistance.
Cool, we should be good unless someone comes with an RPG. The doors on the other hand still need some work and could probably be taken out with a slingshot.
