Transitions between air barrier materials are critical points of failure if not properly detailed. This article explains how to connect dissimilar materials such as sheathing membranes, liquid flashings, and pre-applied barriers.
Overview
Air barrier transitions occur where materials meet at changes in substrate, structure, or geometry. Ensuring continuous airtightness at these points is essential to reduce energy loss and moisture infiltration. Products must be compatible, and transitions should be field-tested and inspected regularly.
Key Materials and Methods
- Use transition membranes (e.g., butyl or silicone tapes)
- Overlap at least 3” onto each surface
- Use compatible primers and sealants where adhesion is critical
- Allow movement at differential joints without tearing
- Conduct adhesion tests during mockups and field QA
🔍 Quick Picks
- Flexible Transition Membrane: SIGA Fentrim Tape
- Primer for Difficult Surfaces: Henry Aquatac Primer
- Liquid Flashing for Detail Work: Prosoco R-Guard Joint & Seam Filler
Conclusion
Transition detailing in air barrier systems must ensure compatibility, continuity, and resilience under stress. Select products based on material chemistry and conduct adhesion tests for long-term reliability.
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Common Transition Challenges
Transitions often fail due to incompatible substrates, movement between materials, or poor installation sequencing. Examples include liquid-applied barriers failing to adhere to factory-applied sheathing membranes, or flexible flashings detaching from rough concrete surfaces. Each transition must be pre-tested or mocked up to ensure success.
