Which material is not recommended for re-cover on an existing asphalt T-lock roof?

Which material is not recommended for re-cover on an existing asphalt T-lock roof?

• A. Asphalt strip shingles
• B. Asphalt shingles
• C. Metal shingles
• D. Clay tiles

Answer: (A)

When re-covering an existing asphalt T-lock roof, the new material should lay smoothly over the old surface and be firmly supported by the deck. Asphalt strip shingles are the thinnest, most flexible type and don’t provide a stable, uniform base for a second layer. Overlaying them on top of the existing T-lock creates ridges and irregularities, making it easy for the new layer to buckle, misalign, or not seal properly around fasteners. The two-layer combination can also trap moisture and complicate flashing and ventilation. In contrast, newer architectural asphalt shingles, metal shingles, or clay tiles (when the structure can support the weight and proper underlayment is used) are more reliably installed as a re-cover. That’s why asphalt strip shingles are not recommended for a re-cover over an existing asphalt T-lock roof.

When re-covering an existing asphalt T-lock roof, the new material should lay smoothly over the old surface and be firmly supported by the deck. Asphalt strip shingles are the thinnest, most flexible type and don’t provide a stable, uniform base for a second layer. Overlaying them on top of the existing T-lock creates ridges and irregularities, making it easy for the new layer to buckle, misalign, or not seal properly around fasteners. The two-layer combination can also trap moisture and complicate flashing and ventilation. In contrast, newer architectural asphalt shingles, metal shingles, or clay tiles (when the structure can support the weight and proper underlayment is used) are more reliably installed as a re-cover. That’s why asphalt strip shingles are not recommended for a re-cover over an existing asphalt T-lock roof.