Perforated gypsum lath has a hole at least 3/4 inch in diameter per how many square inches?

Perforated gypsum lath has a hole at least 3/4 inch in diameter per how many square inches?

• A. 16 sq in
• B. 8 sq in
• C. 12 sq in
• D. 20 sq in

Answer: (A)

Perforated gypsum lath is designed so the plaster has something to key into through the holes, while the lath itself remains strong. The hole size and how closely the holes are spaced are chosen to give enough open area for the plaster to penetrate and grip, without weakening the sheet. The standard calls for a hole diameter of at least 3/4 inch for every 16 square inches of lath surface. In other words, about one perforation per 16 square inches of sheet. This balance ensures a reliable bond between plaster and lath and maintains the lath’s strength.

Perforated gypsum lath is designed so the plaster has something to key into through the holes, while the lath itself remains strong. The hole size and how closely the holes are spaced are chosen to give enough open area for the plaster to penetrate and grip, without weakening the sheet. The standard calls for a hole diameter of at least 3/4 inch for every 16 square inches of lath surface. In other words, about one perforation per 16 square inches of sheet. This balance ensures a reliable bond between plaster and lath and maintains the lath’s strength.