Elena walked in with coffee. “So? Class 25 for the south and west? Or we wait three weeks and lose our crane rental?”
But for the tower that had to survive Seattle’s wind and sun? Only Class 50 would do. astm c920 class 25 vs class 50
“Marcus, listen to me. You’re on the west face of that tower, right? Direct solar gain. In July, that aluminum frame will hit 160°F. At 2 AM, it might be 40°F. That joint is screaming —moving 40, 50 percent easy. Class 25 on a west-facing curtain wall? You’ll see cracks by year two. Then water gets in. Then the insulation rots. Then the lawyers come. Don’t be cheap.” Elena walked in with coffee
Marcus called the structural engineer, Dr. Patricia Okonkwo. “Pat, why Class 50 on the whole building? The north face sees half the movement.” Or we wait three weeks and lose our crane rental
“ASTM C920, Class 50. That’s what the engineer wrote.”