Green Building Foundation

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Green Foundation Resource

A well-planned foundation can make a substantial contribution to controlling heat and cooling costs while eliminating potential moisture and mold problems. There are many different types of foundations to choose from, depending on climate, soils condition, water table and other factors.

See Chapter 4 on Foundations in the Green from the Ground Up book for more details or contact us about training.


Foundations Should be Insulated

Heat is lost through foundation walls, crawl spaces and concrete slabs. Foundations should always be insulated, preferably on the outside to reduce the risk of condensation and make the mass of concrete or block walls part of the conditioned space. An insulated foundation becomes part of the house’s thermal envelope, contributing to energy conservation and creating a more comfortable environment.

Insulating a Basement on the Inside

Although exterior insulation offers more advantages, basements can be insulated from the inside, too. The key is controlling the movement of moisture and mold-inducing condensation as warm air migrates to a cooler surface.

Green Foundation Transition Guide

Some tips and best practices to get started.

Build forms from plywood or aluminum

Initial costs are higher, but they save the trouble and expense of replacing forms made from dimensional lumber

Wood forms made from 2×12’s can only be used a few times and are usually too soiled to be recycled


Reuse forms as much as possible

  • Modular forms are made for most foundation applications
  • Keep as much material out of the landfill as possible can reduce landfill costs
  • Clean and stack used forms after use and reuse them on another project


Use insulated concrete forms

Combine insulation and concrete to form one wall

Polystyrene blocks are stacked to create a foundation wall and concrete is poured into the void for rigidly

Save on both concrete and labor costs

Many companies make ICFs. There are  blocks that are made from recycled woodchips and mineral wool. Most are made from polystyrene


Install a perimeter drain at the base of a foundation wall

A perimeter drain gathers water that might otherwise damage the foundation wall, and channels it away from the foundation.

A perforated pipe wrapped in landscaping felt and placed in a bed of crushed rock located around the footing of the foundation


Insulate foundation walls and slabs with rigid foam

Use at least 2” of closed cell extruded polystyrene

Insulate the exterior of the foundation before backfilling and also below the slab


Specify a minimum of 15% of fly-ash in your concrete

Flyash is not always suitable for flat work as it takes longer to cure

Flyash makes concrete stronger, more durable and water resistant

Flyash is a by-product of coal fired energy plants. When ordering concrete, ask for it to be added to your mix. Notify the structural engineer that you intend to use flyash.


Use a shallow frost protected foundation

Save money and materials by using shallow horizontal insulation for foundations in cold climates



Green Building Training & Certification

Find out when the next Green Building Training is and learn more about Green Building Practices.

Green From the Ground Up Best Practices

Always consider any foundation material as part of the building system. From slabs to crawl spaces to basements, insulate them as well as possible on the exterior before backfilling.

  • Insulating the outside of the foundations is better than adding insulation on the inside. If you do insulate inside, use rigid foam instead of fiberglass batts.
  • When planning a slab-on-grade house, switch to a frost-protected shallow foundation design.
  • Combine structure and insulation by using insulated concrete forms.
  • Use plywood or metal forms to make foundation forms.
  • Make sure the concrete you order contains fly ash. It makes for better, more durable concrete.
  • Use moisture-proof coatins and perimeter drains to keep moisture out of foundations walls and lower the risk of mold while making basements more comfortable.
  • Raise crawl space height to 24 in. to make access easier and include the crawl space in the conditioned space of the house.