Should shingles lift up?

No, shingles should not lift up under normal conditions. Properly installed asphalt shingles should lie flat against each other with a sealed bond from the factory-applied thermally activated sealant strip. This seal creates a continuous water-shedding surface and provides wind resistance. If shingles are lifting up, it indicates a problem that needs attention. Minor lifting shortly after installation in cold weather can be normal temporarily, as sealant needs warm sun to activate, and these shingles should seal within a few weeks in warm weather or be hand-sealed. However, persistent lifting is abnormal. Common causes include wind damage that broke the sealant bond, aging where adhesive loses strength after 15 to 20 years, improper nailing such as high nailing or under-driven nails that prevent shingles from seating flat, poor attic ventilation causing heat warping, or installation over an uneven surface like an existing shingle layer. Lifted shingles are vulnerable to further wind damage, as wind can get underneath and peel them off, and they allow wind-driven rain to infiltrate under the shingle, leading to leaks and deck rot. If you see lifted shingles, inspect them, and if the mat is not creased or broken, you can reseal them with roofing cement. If widespread, have a professional inspection.