SPF provides an air tight seal, and a home without air infiltrating it is much more comfortable. If your home is breathing like most unhappily do, you're letting in outside air, moisture and dust.
This can lead to allergies or the very least prevents your home from providing a nice retreat from allergies outside. Mold and mildew posses a significant health risk and can force people to move out of the homes during expensive remediation while still paying their mortgage. Thankfully, insulating your home with the same SPF air barrier that saves you money, also makes the home healthier and more comfortable for you and your family to live in.