The toughest details are those that have to match up with someone else's work, or those done — even done well — when energy was really cheap. These details are a collection of some common — and tough — dovetails of existing work with retrofits or additions. Bear in mind that green remodeling means creating a new operating regime that is better, not worse, than the one that may well have been working just fine before. Integration of energy efficiency, moisture management, and indoor air quality is much more important and challenging in remodeling than in new construction.
Wall section retrofit // interior perimeter drain // radon vent // 1" rigid interior insulation
It can cost 5 to 10 times more to retrofit a radonColorless, odorless, short-lived radioactive gas that can seep into homes and result in lung cancer risk. Radon and its decay products emit cancer-causing alpha, beta, and gamma particles. mitigation system than it does to do it during new construction. And there is no real way to predict what radon levels will be in a home, even with good soil mapping of radon. A straight chase from foundation to roof is important for passive radon systems (relying only on stack effectAlso referred to as the chimney effect, this is one of three primary forces that drives air leakage in buildings. When warm air is in a column (such as a building), its buoyancy pulls colder air in low in buildings as the buoyant air exerts pressure to escape out the top. The pressure of stack effect is proportional to the height of the column of air and the temperature difference between the air in the column and ambient air. Stack effect is much stronger in cold climates during the heating season than in hot climates during the cooling season.) and for hiding active ones (those with a depressurizationSituation that occurs within a house when the indoor air pressure is lower than that outdoors. Exhaust fans, including bath and kitchen fans, or a clothes dryer can cause depressurization, and it may in turn cause back drafting as well as increased levels of radon within the home. fan).
For more information on radon and radon mitigation, see All About Radon.
Manage the moisture in an old house
Existing foundation walls (and basement floors) are sometimes wet, usually damp, and seldom dry. Rarely do they have perimeter drainage systems, capillaryForces that lift water or pull it through porous materials, such as concrete. The tendency of a material to wick water due to the surface tension of the water molecules. breaks between masonry and wood (or soil) or insulation. To raise the performance of existing foundation and basement floors, you have to make them manage moisture BETTER than they currently do because you are going to insulate and air seal them, significantly decreasing their drying potential.