This is a great forum and an invaluable service.
We’re renovating an old home in Texas (circa 1929) that has 1x6 boards on both sides of the exterior wall that we are going to be leaving in most of the house.
Is the best way to insulate the exterior walls to use blown in insulation or spray foam ?
We get so many different opinions that are devoid of a real reason for using one way over another.
We have not found any diagonal bracing cut-in the studs anywhere that would obstruct the flow of foam or blown in.
Any help you can give is greatly appreciated.
In the long run you are better off with spray foam. Spray foam is an air seal and is much more efficient, as much as 60%. With an older home I doubt there is any type of house wrap on the exterior of the house. I would suggest you have one or two inches of closed cell foam installed first and then finish with the open cell. The closed cell will provide a vapor barrier but is more expensive. The open cell is an air barrier and is a great sound absorber. Check with Demilec in Arlington for a local installer.
I wouldn’t install a vapour barrier on the exterior. You want the wall to be able to diffuse vapour both ways. My choice would be a damp spray cellulose. It has decent air leakage reduction characteristics . You could do a full airseal using the "Airtight Drywall Approach " (ADA) by Jor Lstiburek. With the cellulose, you have antifungal borax as a constituent. And it should be cheaper!!