The effort to accomplish the design and construction of the foundation of RainShine represents an outstanding and easily repeatable model for residential foundations. Careful, rigorous attention to selection of products, design of details and decision regarding construction of this full height residential foundation resulted in substantial energy savings, reduced consumption and lower environmental impact.
Featuring a full basement, foundations are a substantial component of the subject house. Every material and product used in the construction of the foundation either reduces energy costs, is locally manufactured or reduces/eliminates VOC content or contributes to the durability of construction. The following list comprises the foundation features:
- Concrete The mix design for all concrete in this project reduced Portland cement by 40% through incorporation of slag and fly ash. The result is a corresponding net 40% reduction in the CO2 emissions typically resulting from concrete production. The mix design was use for all footings, reinforced retaining walls, basement slab and concrete block retaining wall grout. Fly ash and slag used in the concrete mix are industrial by-products. Also, the cement, aggregate, sand, admixtures, fly ash and slag used in the concrete are locally manufactured or mined. Any surplus concrete was returned to the ready mixed concrete production facilities used for this project. 100% of returned material was diverted from landfill by collecting wash water and aggregate for reuse in concrete mixes in this and other projects.
- Concrete block All concrete block in the project contains 10.25% locally produced fly ash. Fly ash is used in substitution for Portland cement resulting in a net reduction in the CO2 emissions required to produce the concrete block. The concrete block consists of locally mined or manufactured materials, including cement, fines and aggregate. Additionally all concrete block cells are filled with the above high slag and fly ash content concrete mix.
- Steel reinforcing All steel reinforcing used in concrete footings, concrete retaining walls, concrete block retaining walls and concrete slabs are produced locally from 87% post-consumer and 17% post industrial recycled content.
- Footing drains All footing drains are manufactured from 100% recycled postindustrial regrind.
- Filter fabric Footing drain filter fabric is manufactured from 100% recycled postindustrial materials.
- Waterproofing Foundation waterproofing is spray applied low VOC water based, anionic emulsion.
- Vertical drainage All foundation walls are faced with a vertical drainage system manufactured from 100% recycled content.
- Protection board All foundation protection board is manufactured from 100% recycled postindustrial materials.
- Capillary break All footings are separated from their concrete or concrete block bearing walls with a polyethylene capillary break increasing building durability by preventing soil moisture migration into the building envelope.
- Concrete forming Reusable concrete forms were employed to form all concrete foundation walls.
- Concrete forming 100% recycled paperboard forms were employed to form all round piers supporting decks and porches.
- Form release agent Form oil release agent used for the foundation walls is a biodegradable low VOC (55g/l) product composed of organic lubricants emulsified in water.
- Vapor retarder All under-slab vapor retarder membranes are manufactured from 100% recycled post-industrial content.
- Foundation finish Foundations are finished with natural hydraulic lime (NHL), a zero VOC, self-healing, integrally colored, recyclable stucco. Natural hydraulic lime has a high level of vapor exchange and its mineral composition breathes, eliminating entrapment of moisture and thereby resists dry rot and mold.