Im adding cable rafter ties to my 1952 cinder block home. 4/12 pitch asphalt shingles. To make my home more hurricane resistant I have added hurricane straps and gable supports. I will be getting a new shingle roof this year. Before the new roof Im sistering a few cracked rafters. During the reroof, screws will be used to hold the planking to the rafters.

There are NO rafter ties on this house and only a few collar ties. I dont know how its stayed together with just toe nails. Ridge is not sagging and walls are not bowing. Still, Ive decided to add rafter ties. Aside from one video, I know nothing about using cable to do this. However, cable would be easier and maybe stronger too. I need to know how strong my cables needs to be. All online roof load calculators need to know roof design load. I dont know this.

Im looking for help in this cable tie project and suggestions of good suppliers.

thanks,
pa