Help with understanding the scope of a project

I’m looking to add some insulation to a wall of my house and had a well regarded insulation company come out to quote. Their proposal was to remove siding, drill into the backer board to fill cavities with insulation then replace the siding. No mention on any kind of wrapping material. Is that normal or should thee be some kind of weather protection (tyvek house wrap, etc.) that needs to go behind the siding?