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Proper installation of flashing for drainage

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Taped Insulating Sheathing Drainage Planes

Guide

Guide describing techniques for installing insulating sheathing as a continuous drainage plane on walls.

Proper shingling of drainage plane materials

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Drainage Plane Behind Exterior Wall Cladding

Guide

Guide describing installation of a fully sealed continuous weather resistant barrier to provide a drainage plane to keep rainwater out of above-grade walls.

Stucco is installed over rigid insulation, which is installed over a drainage plane consisting of a drainage gap and building wrap layer over the sheathing

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Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes

Reference

Measure Guideline research report providing simple, long term, and durable solutions when using tapes and flashing membranes in conjunction with the exterior face of rigid polymeric foam sheathing to create the drainage plane of a wall system.

Building Enclosure: Stone Veneer Installation Interior Drainage Plane

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Drain the Rain…On the Plane…the Drainage Plane, BSI–112

Reference

Report covering the rainwater performance of building assemblies.

Wrong - Mortar is clogging 1" drainage gap behind brick wall.

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Install a housewrap drainage plane between the SIP panels and the exterior cladding

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Wrong – There is no flashing installed at the bottom of the exterior walls to create a drainage system

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Right – There is flashing installed at the bottom of the wall to create a satisfactory drainage system

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Wrong – There is no flashing installed at the bottom of the exterior walls to create a drainage system

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The weep holes are spaced at the correct distance to provide a complete drainage system

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Wrong – The corners are not properly flashed, leaving a vulnerable area in the drainage system

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Right - Basement slab with a capillary break of either gravel or a drainage mat.

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The sheathing has rotted because there was not a sufficient drainage gap behind the stucco cladding

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Right – Furring strips provide a drainage gap between the rigid foam and the siding.

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Improving Drainage and Drying Features in Certain Conditions: Rain Screen Design for Absorptive Cladding

Reference

Guide detailing best practices on how to build wall assemblies with absorptive claddings such as brick, stone that drain and dry well.

Right – The building felt is installed on all exterior walls and provides a complete drainage system

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Right – The water-resistant barrier is layered over the step flashing to provide a complete drainage system

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Bees made a nest in the drainage plane behind a brick veneer wall by entering via unscreened weep holes

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Install all layers of the drainage plane to overlap, not underlap, to direct bulk water down and out of the wall.

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The water-resistant barrier, weep screed, and stucco lathe are properly layered and will create a complete drainage system

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Proper flashing around windows is especially important when the rigid foam serves as the drainage plane in the wall

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Right – The flashing is properly installed to create a complete drainage system with continuous rigid insulation sheathing/siding

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Standard Specification for Manufactured Polymeric Drainage and Ventilation Materials Used to Provide a Rainscreen Function, ASTM E2925–19a

Reference

Specification describing criteria for manufactured polymeric materials used to provide a rainscreen function, a means for the drainage of liquid moisture and the ventilation of vapor moisture that enters an above-grade exterior wall assembly which was published in the year 2019, and is available for...

Right – The water-resistant barrier covers the entire house and the seams are taped to provide a complete drainage system

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Wrong – If the insulated sheathing will serve as an air barrier and drainage plane, any cuts and seams must be taped or sealed.

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Right – The rigid insulation covers all exterior walls and all seams are taped to provide a complete drainage system

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