figure 1 removing wood floor above inaccessible space at Rhinbeck House
When beginning a DER, the first task is to go through the building and find the existing problems, such as water intrusion, rotten wood, and other items that need to be addressed prior to starting the DER work. Moisture might be present and not causing a problem because the air leakage rate is high enough that the moisture is being carried away. In the Rhinebeck House we had to remove a framed floor and replace it with a concrete one because the floor was only six inches from the ground. The fiberglass insulation had failed (see figure 1). It fell out of place and became mouse habitat. The only reason this floor did not fail years ago is because of the substantial quantity of air movement under it, which kept the area dry. If left in place, the moisture would have become a problem after the DER eliminated the air flow, and the floor would have rotted away in short order. Air movement is the primary mover of moisture in buildings, and tightening up a building removes this drying mechanism, so you need to be sure to find and remove all sources of moisture. Check the exterior drainage as well and make sure the water drains away from the building during storms and correct any problems found.
The homeowners may want to make changes to the building, be sure to investigate and incorporate the changes into the DER process. For instance, at the Cottekill House we added a small window and brought the rear porch into the conditioned space, or the Rhinebeck House where we changed several windows and made provisions to move the kitchen. Once the DER process is complete it would be costly and counterproductive to rip it apart to move a window, or add a room.
Once a plan is established, a building permit is required. Verdae, LLC did not have any trouble obtaining them because we referenced the tables in the NYS Energy Code which specify the size and quantity of screws needed to support the dead load of the siding. As of May 2016, the needed tables can be found on pages 30 and 31 of the Energy Conservation Construction Code of New York State, 2010 version. Be sure to use the tables from the most current code.