Technical Booklet C Site Preparation and Resistance to Contaminants and Moisture·Page 37·7.6
Dry joint design for roofing systems
Dry joints in roofing sheets must be designed to prevent water passing through them or must drain water that enters without it penetrating the roofing system backing.
Dry joints between roofing sheets should be designed so that precipitation will not pass through them, or the system should be designed so that precipitation which enters the joints will be drained away without penetrating beyond the back of the roofing system.
Whether dry joints are suitable or not will depend on the design of the joint or the design of the roofing system and the severity of the exposure to wind and rain.
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