House Foundations

A home’s foundation is crucial to its long-term sustainability. When properly designed and constructed, it forms a solid, insulated, and sealed barrier that protects against the elements and pests—minimizing the need for future pest controls and maximizing efficiency. Builders should prioritize energy efficiency and environmental responsibility in their construction practices to reduce strain on the environment.

While some builders may cut corners, building codes and inspections exist to uphold quality standards. Unfortunately, not all municipalities enforce strict energy efficiency codes, leading to long-term environmental and economic costs.

The Build Greener Project is dedicated to helping builders adopt sustainable practices and ensure that every home meets the highest standards of efficiency and sustainability.

Concrete Slab Foundations

Concrete slab foundations provide a sturdy, low-maintenance base for residential homes. They are cost-effective, quick to install, highly durable and less prone to issues like mold, mildew, or pest infestations, minimizing the need for toxic chemical treatments down the road. Additionally, slab foundations contribute to energy efficiency by reducing air leakage and providing thermal mass that helps regulate indoor temperatures. Their long-term durability, minimal upkeep, eco-friendly nature make slab foundations an excellent choice for sustainable residential construction.

There are many different materials and methods to create an eco-friendly foundation today and each climate will be unique, for our discussion we are going to focus on a stem wall concrete slab foundation to show the key elements of an energy efficient and sustainable foundation design.

Advantages of Stem Wall Foundations

Elevated Structure: providing protection from flooding and allowing better ventilation.

Versatility: accommodate sloped or uneven terrain.

Structural Strength: distribute the load of the building evenly and resists settling.

Pest and Water Protection: When properly sealed, they can provide a strong barrier.

Insulation: can be combined with insulated floors and crawl spaces for energy efficiency.

Framing with Pest-Resistant Steel

Steel framing is lightweight, installs quickly, and is more cost-effective than wood framing. 2x6 studs at 24 inches on center allows for more insulation. Adding radiant barriers helps to reduce the thermal conductivity of the steel. Additionally, steel can be recycled without losing its quality, making it an excellent building material. Pest-resistant steel eliminates the need for homeowners to apply toxic chemicals to protect their homes.

Framing with Cinderblock

Cinderblock framing offers superior durability, fire resistance, and sound insulation compared to traditional wood framing. The thermal mass of cinderblocks helps regulate indoor temperatures, making homes more energy-efficient. Cinderblocks are also resistant to pests and mold, reducing the need for toxic chemical treatments. Additionally, cinderblocks are sourced from natural materials, and they are extremely durable and require very little maintenance.

House Framing

Timber house framing, also know as stick framing, is the most common style of framing, and is made up of 2x4 and/or 2x6 wood studs 16" on center or 24" on center. More efficient engineering in framing is called Optimum Value Engineering (OVE), also called Efficient Framing or Advanced Framing is more in line with sustainability, as explained below:

Material Efficiency: Fewer studs are used due to the wider spacing (24 inches on center), reducing the amount of lumber needed. This can lower material costs and environmental impact by cutting down on wood consumption.

Structural Benefits: The larger 2x6 studs allow for greater structural capacity, which is beneficial for supporting heavier loads and accommodating taller ceilings or more floors.

Better Insulation: The 2x6 studs provide more room for insulation, which increases the home's thermal resistance (R-value). This results in better energy efficiency and lower utility costs by improving heating and cooling performance.

Eco-Friendly: By using less wood and providing better insulation, advanced 2x6 framing is generally considered more environmentally friendly. It also works well with sustainable building materials like mineral wool or cellulose insulation.

House Insulation

The minimum insulation requirements for a standard house build depend on the climate zone, as determined by the International Energy Conservation Code (IECC). The U.S. is divided into 8 climate zones, with varying insulation requirements for different parts of the home (exterior walls, interior walls, attic, etc.).

Minimum Insulation Requirements (Based on IECC 2021)

1. Exterior Walls (R-Value)

Climate Zones 1-2, Warm: R-13 (2x4 walls) or R-20 (2x6 walls).

Climate Zones 3-5, Moderate: R-20 or R-13 + R-5 continuous insulation (CI)

Climate Zones 6-8, Cold: R-20 + R-5 CI or R-15 + R-10 CI

Explanation: Continuous insulation (CI) is an additional layer of insulation placed on the exterior to reduce thermal bridging through the studs, which improves energy efficiency.

2. Interior Walls (R-Value)

Insulation for interior walls is typically not required by building codes unless being used for soundproofing or fire resistance, as interior walls do not directly affect the home’s thermal envelope. However, R-13 or R-15 batts may be used for interior walls when soundproofing is desired, especially between rooms like bathrooms or bedrooms.

3. Attic/Ceiling (R-Value)

Climate Zones 1-2: R-38 insulation is required.

Climate Zones 3-5: R-49 insulation is typically required.

Climate Zones 6-8: R-49 to R-60 insulation, depending on the zone.

Additional Considerations

Continuous Insulation (CI): Some zones require continuous insulation over the exterior of walls to improve energy efficiency by reducing thermal bridging.

High-Performance Homes: Homes built to achieve better energy performance, such as net-zero energy homes, may go beyond these minimum standards and use higher insulation values.

Local Code Variations

While the IECC sets the baseline for minimum insulation requirements, local codes may differ, and some states have more stringent insulation requirements (like California with Title 24 standards). It's essential to check the specific requirements of your area for compliance.

For a standard house, these are the minimum insulation requirements, higher insulation values will improve energy efficiency, lower utility costs, and create a more comfortable living environment.

Insulation Materials Recommended

Build Greener has determined the most cost effective and eco friendly options are: Mineral Wool, Cellulose, and Radiant and Vapor Barriers.

Radiant Barrier for roof exterior

Radiant Barrier for Attic

Continuous Exterior Insulation

Interior Insulation-Mineral Wool

Cool rooftops

are painted white and therefore are solar reflecting and can reduce internal building temperatures by up to 30 percent, making the building cooler and more comfortable during the hot summer months. Every 2,500 square feet of roof that is coated can reduce a city's carbon footprint by ​one​​ ton of CO2 and help fight climate change, reduce the need for air conditioning, which can extend the life of cooling equipment. Cool roofs can improve air quality by slowing the formation of ground-level ozone, which is a major component of smog.

Eco-Roof Materials:

Metal, clay, slate, cedar shingles & recycled asphalt shingles. Metal & asphalt shingles would be the most affordable options; however, asphalt shingles would be the least eco-friendly option.

Plumbing

A quality plumbing installation ensures the longevity and durability of the home's water supply system. Poor installation can lead to leaks, pipe bursts, and water damage, which can result in costly repairs and structural issues, an open invitation to insects over time. Properly installed plumbing helps maintain the integrity of the home, reducing the risk of future failures and increasing the lifespan of the system.

Today there are several types of plumbing products to choose from: Copper, CPVC, PEX, Stainless Steel, & Galvanized Steel.

Copper: A long-standing choice for plumbing, is durable, resistant to corrosion, and has excellent thermal properties. It’s safe for drinking water and has a long lifespan, making it a high-quality option for water supply systems. However, copper can be expensive and may require more skilled labor for installation.

CPVC (Chlorinated Polyvinyl Chloride): CPVC is a cost-effective material that is resistant to corrosion, making it suitable for both hot and cold water lines. It’s often used in areas where chemical resistance is important, but it can be more brittle, making it prone to damage during installation.

PEX (Cross-Linked Polyethylene): PEX piping has become a popular choice due to its flexibility, ease of installation, and resistance to freezing. PEX is cost-effective, requires fewer fittings, and can be routed easily, reducing potential leak points. It is easy to spot dues to its distinct colors blue & red. There is also a white variation that offers larger fittings for better water flow.

Build Greener recommends: copper, if you can afford it, and CPVC is our next choice. We do not recommend PEX because it leaches chemicals and toxins during manufacturing and while in use. In addition, PEX does not perform well in homes that have high water chlorination. PEX has an antioxidant chemical added to counter the chlorine, but over time it degrades, so PEX longevity could be short lived. Finally PEX is not recyclable and end up in land fills.

House siding should be durable, protective, recyclable and sustainable. Metal siding is a great option if you are trying to budget. Stucco is another affordable siding material. Fiber cement board is another great option. Brick or stone are eco materials, but the cost and labor is expensive.

Gutters

Essential for Water Management Gutters play a crucial role in directing rainwater away from your home’s exterior and foundation. By collecting rainwater and channeling it through downspouts, gutters prevent potential water damage. It’s important to ensure that water is drained at least 4-6 feet from the foundation; in some cases, depending on the landscape and soil conditions, extending the drainage distance to 10-20 feet may be necessary.

Additionally, consider conserving rainwater by installing a rain barrel or similar system. Collected rainwater can provide a sustainable source for irrigating your landscaping or garden, helping you save water while nourishing your plants.

Flooring: The best flooring is no flooring! Polished concrete is beautiful and eco-friendly. On a serious note, concrete flooring is the way to go when you have a concrete foundation. The next best option would be ceramic or porcelain tile or wood flooring.

Eco Paint: Plastic and VOC free! Milk paints are non-toxic, environmentally friendly paint made from natural ingredients like milk protein, lime, and pigments. Milk paint is one of the oldest known forms of paint, dating back thousands of years. It's been found in cave paintings and Egyptian tombs.