03/15/2026
Great process!
RAINSCREEN SIDING AND DECK LEDGER FLASHING DETAIL
CONCEPT EXPLANATION
This technical illustration provides a detailed cross-section of a rainscreen siding system integrated with a deck ledger attachment. The primary goal of this design is moisture management. By using furring strips to create a gap between the siding and the housewrap, the system allows for continuous airflow, which enables any moisture that penetrates the siding to dry out or drain away. Simultaneously, the illustration highlights the complex layering of flashing and membranes required to protect the structural rim joist and ledger from water damage at the critical junction where the deck meets the house.
KEY COMPONENTS
• Rainscreen Gap: Created by 1x furring strips, this space allows for vertical airflow behind the siding to prevent rot and mold.
• Moisture Barriers: Includes housewrap for the main wall and a self-adhering membrane that laps over the flashing to create a watertight seal behind the deck.
• Flashing System: Features a ledger flashing with a 5-inch wall leg to prevent water from pooling behind the deck board, and a drip cap at the foundation transition to direct water away from the concrete.
• Foom Insulation & Protection: Rigid foam insulation is used for thermal performance, protected at the bottom by a plastic or metal U-cap and a corrugated vent strip to allow air in while keeping pests out.
• Structural Framing: Shows the relationship between the 1/2-in. sheathing, the 2x band joist, and the deck ledger which is bolted to the structure.
SYSTEM OVERVIEW
The illustration emphasizes the "belt and suspenders" approach to modern building science. By combining continuous exterior insulation, a ventilated rainscreen, and rigorous flashing details at the ledger, the assembly ensures that the building envelope remains durable and energy-efficient. The design successfully addresses the three biggest threats to a wall assembly: water intrusion, air leakage, and thermal bridging.