See Chapter 6, Room Additions in the book Green Remodeling for more details. 

 

 

 

 

Foundation Practices for Additions Checklist

  • Insulate your foundation! If you are pouring a concrete slab, be sure to insulate below it with rigid foam.
  • Insulate your foundation walls
  • Install a foundation drain around the perimeter to prevent moisture damage
  • Specify a minimum of 15% of fly-ash in your concrete instead of cement
  •  Insulate the existing foundation or crawl space if possible

Green Additions/Remodel Best Practices

Foundations for Additions

Insulating foundations is a critical piece of your green remodel. An uninsulated foundation may account for up to 50% of the heat loss from an otherwise tightly sealed, well-insulated house in a cold climate. Proper installation of foundation insulation material is necessary to avoid the condensation, material damage, and structural decay caused by the difference in temperature between the house interior and adjacent earth.

Foundations need to be designed by a structural engineer. An engineer will design the appropriate foundation based on soils conditions, building loads and your current foundation system. If your new addition is over an existing foundation, an engineer will need to evaluate if your existing foundation can support this new load.

Foundations are typically one of three types:

  • full basement - extend the farthest underground, and are typically used in areas where there are deep frost lines, and low water tables
  • crawlspace - a basement with shorter walls one to three feet deep.
  • slab-on-grade - a cement slab on top of the earth

Talk to your structural engineer about green practices. Ask if a shallow frost protected foundation is suitable in your area and for your situation.