Final answer:
It is necessary to walk in, roll, or weigh down insulation to ensure a secure bond and prevent air gaps during installation, especially when the adhesive is used to attach insulation material to a surface.
Step-by-step explanation:
When insulation is being adhered in a construction or building project, it is necessary to walk in, roll or weigh down insulation in specific circumstances to ensure a secure bond between the insulation material and the surface to which it is being attached. This process is crucial during installation to prevent air gaps, which can diminish the insulation's effectiveness. Walking in or rolling the insulation helps in evenly distributing the adhesive and pressing the material into place, while weighing it down is often done when using rigid insulation panels that need to stay flat and in contact with the adhesive until it sets.