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Drainage techniques for slab-on-grade foundations

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Rigid Foam Insulation Installed over Existing Foundation Slabs

Guide

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.

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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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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.

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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.

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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.

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This house design in the Hot-Humid climate uses a slab foundation, masonry walls, and an Exterior Insulation Finish System (EIFS) cladding.

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

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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

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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.

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Pouring the slab

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

Guide

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

Concrete Slab over Polyethylene

Video

Video describing concrete slab over polyethylene barrier.

Building Enclosure: Foundation Overview

Video

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

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Slab Happy, BSI-059

Reference

How hard can it be to insulate a flat sheet of concrete? I mean you only have three choices – on the top, on the bottom, or on the edge. OK, you might have some combination of the three as well.

Foundation Design Handbook

Reference

Handbook providing guidance on the design and construction of foundations for homes, including insulation, air sealing, and water management details for basements, crawlspaces, and slabs.

Right – A sump pump with a perforated sump pit was installed in the crawlspace slab to reduce water accumulation under the slab

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Drainage techniques for slab-on-grade foundations

Rigid Foam Insulation Installed over Existing Foundation Slabs

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

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.

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.

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.

This house design in the Hot-Humid climate uses a slab foundation, masonry walls, and an Exterior Insulation Finish System (EIFS) cladding.

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

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

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

Pouring the slab

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

Concrete Slab over Polyethylene

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.

Slab Happy, BSI-059

Foundation Design Handbook

Right – A sump pump with a perforated sump pit was installed in the crawlspace slab to reduce water accumulation under the slab

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

Concrete slab over polyethylene sheeting as capillary break

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

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

A method for preventing waterproofing issues at the intersection of a concrete slab and a rock anchor.

Capillary Break at Crawlspace Floor - Polyethylene Sheeting under Concrete Slab

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

Elevated slab construction with no water sensitive materials on first level

A method for preventing waterproofing issues at the intersection of a concrete column, concrete slab, and concrete pier.

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

Final Grade Slopes Away from Foundation