BASC Search | Building America Solution Center

Drainage techniques for slab-on-grade foundations

Publication Date

Tue, 01/01/2013 - 12:00

Rigid Foam Insulation Installed over Existing Foundation Slabs

Guide describing how to insulate an existing slab floor by adding rigid foam insulation over the slab then installing a floating subfloor.

Right – The seam between the slab and the foundation wall is sealed with urethane caulk.

To help keep the monolithic slab-on-grade foundation dry, the site’s surfaces is graded away from the structure, the slab is poured on a bed of gravel, and using a vapor barrier will separate the foundation from the sill plates.

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.

Publication Date

Mon, 07/01/2013 - 12:00

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.

Publication Date

Mon, 07/01/2013 - 12:00

Any holes through the vapor barrier installed over the basement floor slab are thoroughly sealed as part of the foundation water barrier system.

Publication Date

Tue, 01/01/2013 - 12:00

A layer of pea gravel or crushed stone, 4 inches thick and sloped 5%, provides a pest-resistant ground break around the perimeter of a slab foundation

Publication Date

Mon, 03/01/2021 - 12:00

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

Publication Date

Mon, 07/01/2013 - 12:00

Pouring the slab

Patio Slabs, Porch Slabs, Walkways, and Driveways Slope Away from House

Guide describing how to correctly slope solid surfaces outside a home so rainwater flows away from the home.

Building Enclosure: Foundation Overview

Right – The slab is coated with two coats of epoxy paint to minimize moisture transfer through the slab from the ground.

Termite-Resistant Foundations and Walls

Guide describing techniques and measures for increasing the termite resistance of a home's foundations.

There is no polyethylene sheeting installed between the ground and the slab

Publication Date

Tue, 02/01/2011 - 12:00

Concrete slab over polyethylene sheeting as capillary break

Publication Date

Thu, 02/01/2018 - 12:00

Spray Foam Interior Insulation for Existing Foundation Walls

Guide describing how to insulate an existing foundation wall by adding spray foam insulation to the interior side of the wall.

There is polyethylene sheeting installed to provide a capillary break between the ground and slab

Publication Date

Tue, 02/01/2011 - 12:00

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

Publication Date

Thu, 02/01/2018 - 12:00

Capillary Break at Crawlspace Floor - Polyethylene Sheeting under Concrete Slab

Guide describing how to install a capillary break to help manage moisture in foundations.

Capillary Break Beneath Slab - Polyethylene Sheeting or Rigid Insulation over Aggregate or Sand and Geotextile Mat

Guide describing how to install a capillary break under a slab foundation using either polyethylene sheeting or rigid insulation installed over aggregate or over sand and geotextile matting.

The existing slab is retrofitted with epoxy paint, rigid foam insulation, sleepers (furring strips), and subfloor.

Publication Date

Sun, 06/01/2008 - 12:00

Right - Retrofit of an existing basement slab by adding dimple plastic mat, rigid foam insulation, and a floating subfloor.

The existing slab is retrofitted by coating with epoxy paint, then installing rigid foam insulation and a floating subfloor.

Publication Date

Mon, 07/01/2013 - 12:00

Right – The drain slopes away from the foundation and terminates at the proper distance

Publication Date

Tue, 02/01/2011 - 12:00

An uninsulated (or existing insulated) basement slab is retrofitted to reduce moisture transmission by sealing with epoxy paint.

Publication Date

Thu, 09/10/2015 - 12:00

Impervious surfaces like patio slabs, sidewalks, and driveways that are within 10 feet of the home should slope away from the house.

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

Publication Date

Mon, 07/01/2013 - 12:00

Right – Polyethylene sheeting is laid over aggregate and over footing to provide a capillary break between the ground and the slab and between the footing and the stem wall

Polyethylene sheeting covers the aggregate and extends down and under the footing to provide a capillary break between the ground and the slab and monolithic footing

DWG

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Wrong – Drain pipe has been cut and foundation penetration has not been properly sealed

Publication Date

Tue, 02/01/2011 - 12:00

Exterior Insulation for Existing Foundation Walls

Guide describing how to insulate a new foundation wall or an existing foundation wall by adding rigid insulation to the exterior side.

Rigid insulation and water control layers are installed on the exterior of a flat foundation wall; spray foam insulates the rim joist

Publication Date

Mon, 07/01/2013 - 12:00

Wrong – The footing drain pipe should end at least 10 feet from the foundation if above ground or should drain into a drywell or storm sewer.

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.

Publication Date

Thu, 03/01/2012 - 12:00

Wrong – Polyethylene sheeting does not extend beyond edge of aggregate to separate the footer from the stem wall which will be poured next

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

Comprehensive water management features include a capillary break (≥ 6-mil polyethylene sheeting) at all crawlspace floors

Publication Date

Fri, 05/01/2009 - 12:00