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Site Drainage Practices to Minimize Localized Flooding

Information Guide

Information guide describing steps that builders can take to reduce the likelihood of standing water and localized flooding around the foundation of a home during rainy conditions.

Drainage techniques for slab-on-grade foundations

Drainage techniques for slab-on-grade foundations

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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

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.

Passive House Foundation Wall and Drainage: Karuna Video #5

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Video describing the foundation wall and drainage system in a passive house.

Drainage and waterproofing system components in a basement, footing detail

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Drainage and waterproofing system components of a basement, sill detail

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Crawl space drainage: crawl space below grade

Crawl space drainage: crawl space below grade

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Crawl space drainage: crawl space floor at or above grade

Crawl space drainage: crawl space floor at or above grade

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This building foundation has a drainage layer located on the exterior of the waterproofing membrane.

This building foundation has a drainage layer located on the exterior of the waterproofing membrane.

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Poor drainage conditions can enable water to pool around the home.

Poor drainage conditions can enable water to pool around the home.

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

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

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Crawl space drainage: crawl space below grade with dual drains

Crawl space drainage: crawl space below grade with dual drains

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

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

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Traditional methods of site drainage, such as site grading, can be difficult to achieve on urban sites.

Traditional methods of site drainage, such as site grading, can be difficult to achieve on urban sites.

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A dimpled rain mat and perforated drain pipe provide drainage around the basement foundation.

A dimpled rain mat and perforated drain pipe provide drainage around the basement foundation.

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Drainage and waterproofing system components in a basement, single perimeter drain system, footing detail

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Right – Foundation drainage mat was installed over the waterproof membrane that covers the sealed crawlspace window

Right – Foundation drainage mat was installed over the waterproof membrane that covers the sealed crawlspace window

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A common method of addressing significant groundwater leakage in the foundation is to line the interior perimeter of the foundation with a drainage layer.

A common method of addressing significant groundwater leakage in the foundation is to line the interior perimeter of the foundation with a drainage layer.

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A common method of addressing significant groundwater leakage in the foundation is to line the entire foundation assembly, including the slab, with a drainage layer.

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Right - The existing basement slab is retrofitted by installing a dimple plastic drainage mat, rigid foam insulation, and a floating subfloor.

Right - The existing basement slab is retrofitted by installing a dimple plastic drainage mat, rigid foam insulation, and a floating subfloor.

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Right - The service penetration in the waterproofing membrane is well-sealed, and there is a drainage mat acting as a protective layer on the interior of the soldier piles and wood lagging.

Right - The service penetration in the waterproofing membrane is well-sealed, and there is a drainage mat acting as a protective layer on the interior of the soldier piles and wood lagging.

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Spray foam extends down the foundation wall to the slab, which has been retrofitted by adding dimple plastic drainage mat and rigid foam insulation.

Spray foam extends down the foundation wall to the slab, which has been retrofitted by adding dimple plastic drainage mat and rigid foam insulation.

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Spray foam extends down the inside of the foundation wall to the uninsulated slab; because the wall lacked exterior perimeter drainage, the slab was cut and an interior footing drain was installed.

Spray foam extends down the inside of the foundation wall to the uninsulated slab; because the wall lacked exterior perimeter drainage, the slab was cut and an interior footing drain was installed.

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Right – A dimpled plastic rainscreen product is installed over liquid-applied waterproofing on the exterior of the ICF foundation walls, directing water down the wall to the perimeter drain tile, thus encouraging drainage around the foundation.

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This basement is insulated on the exterior with rigid foam over dampproofing, with granular backfill and footing drains to facilitate drainage away from the foundation, a termite shield to protect from pests, and cellular PVC to protect the rigid foam.

This basement is insulated on the exterior with rigid foam over dampproofing, with granular backfill and footing drains to facilitate drainage away from the foundation, a termite shield to protect from pests, and cellular PVC to protect the rigid foam.

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Good water management practices like sloping grade away from house, and installing gutters, perimeter drain pipe, a capillary break, and free-draining soils or drainage mat protect the foundation from water saturation.

Good water management practices like sloping grade away from house, and installing gutters, perimeter drain pipe, a capillary break, and free-draining soils or drainage mat protect the foundation from water saturation.

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Wrong - Class I vapor retarder over framed basement walls can cause condensation, mold, and rotting because plastic prevents drying to the inside; the outside should have waterproofing and vertical drainage, and the framing should be spaced from the wall.

Wrong - Class I vapor retarder over framed basement walls can cause condensation, mold, and rotting because plastic prevents drying to the inside; the outside should have waterproofing and vertical drainage, and the framing should be spaced from the wall.

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Spray foam insulation extends down the foundation wall to the slab, which has been retrofitted by cutting the slab to install drainage mat against the wall and a new perimeter footing drain, along with rigid foam plastic above the slab.

Spray foam insulation extends down the foundation wall to the slab, which has been retrofitted by cutting the slab to install drainage mat against the wall and a new perimeter footing drain, along with rigid foam plastic above the slab.

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Right – The raised-slab, CMU block stem wall, above-grade walls, and roof of this house use flood damage-resistant materials, integrated water, vapor, and air control layers, and construction methods which promote good drainage and rapid drying

Right – The raised-slab, CMU block stem wall, above-grade walls, and roof of this house use flood damage-resistant materials, integrated water, vapor, and air control layers, and construction methods which promote good drainage and rapid drying

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