BASC Search | Building America Solution Center

Proper installation of flashing for drainage

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Before sealing and insulating the crawlspace, the windows were sealed, the window wells backfilled, and sumps pumps were installed that discharged to the gutter downspouts

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Wrong – This vented crawlspace has standing water because steps were not taken to address site conditions that led to bulk water flow into the crawlspace

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Wrong – A poorly sealed window and window well allow bulk water to enter the crawlspace from ground that slopes toward the structure

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Water-proof materials cover the exterior side of crawlspace windows in a crawlspace retrofit, while foil-faced rigid foams seals and insulates the inside face of the openings

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Concrete slab pan flashing for doors

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Sheet metal pan flashing for doors

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Basement Insulation, Info 511

Reference

Information sheet describing techniques for insulating basements.

Right – Foil-faced insulation was added after the crawlspace was dried and sealed by diverting water runoff, sealing off crawlspace windows and vents, and adding sump pumps and exhaust fan ventilation

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

Reference

Report covering the rainwater performance of building assemblies.

Complete water management strategy for a below-grade wall

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Capillarity Sucks, BSI-123

Reference

Article describing the principle of capillarity in construction materials.

Water Managed Wall Systems, PA-0301

Reference

Document outlining a well-detailed drainage plane and flashings.

No Sweat, BSI-094

Reference

Guide providing information on controlling attic ductwork sweating.

Right – This crawlspace window was completely sealed off on the inside and outside with air barrier and water-proof materials and the window well was filled in to an above-grade height to prevent bulk water from entering the crawlspace

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The ventilation space in this vented over-roof keeps the roof cool to prevent ice dams over the unvented attic

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BSC Information - Common Flashing Details for All Climates, Sheet 303

Reference

Brochure providing information about flashing in all cimates.

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

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Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes

Reference

Case study about how to properly tape insulating sheathing drainage planes.

Formable pan flashing and back dam for window

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Easy access

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Mass Save Deep Energy Retrofit Builder Guide, GM-1302

Reference

Guidebook providing useful examples of high performance retrofit techniques for the building enclosure of wood frame residential construction in a cold and somewhat wet climate.

Moisture Durability with Vapor-Permeable Insulating Sheathing

Reference

Report about exterior sheathing insulation and inward driven moisture issues.

They All Laughed, BSI-026

Reference

Article describing the evolution of the IRC to permit class 3 vapor retarders (latex paint) in walls coupled with exterior continuous insulation to allow drying and reduce condensation risk.

Hockey Pucks and Hydrostatic Pressure, BSI–057

Reference

Report covering control of hydrostatic pressure in wall assemblies.

Moisture Management for High R-Value Walls

Reference

Report explaining moisture-related concerns for high R-value wall assemblies and discusses past Building America research work that informs this study.

Water Managed Roof – Re-roofing and Adding Insulation over a Flat Roof

Guide

Guide describing an approach to re-roofing an existing flat roof to improve thermal, water, and air control performance.

Installing Windows with Foam Sheathing on a Wood-Frame Wall

Reference

Report with guidance for installing windows with foam sheathing on wood-frame walls.

Drainage Plane/Water Resistive Barrier, Info-301

Reference

Brochure describing drainage planes, also referred to as water resistive barriers.