A rear addition under the 50 percent rule

The brief

What they came to us with

The owners wanted a primary suite and a family room on the back of the house. The property sits in a mapped special flood hazard area, and the first design they had been shown by another contractor would have pushed the project cost past half the structure's assessed value.

Crossing that line would have required the entire existing house to be brought into current flood compliance, which on this lot meant elevating it. That was not in the budget, so the scope had to be designed to stay under the threshold.

What we did

• 620 square foot rear addition on a thickened-edge slab with the finished floor set above the design flood elevation
• Primary suite, bathroom and family room, with the existing rear wall opened at two points with new lintels
• Full mechanical redesign with a second system for the addition rather than extending the existing ductwork
• New impact-rated openings throughout the addition with product approval numbers on the permit set
• Existing electrical panel relocated and upgraded to 200 amp
• Exterior stucco texture matched and the affected elevation repainted

What made it difficult

How it finished

• The addition was permitted and built without triggering compliance work on the existing house.
• The new suite runs on its own system and holds humidity properly in August.
• The owners have a written record of the improvement cost for the next time they build.

Another builder quoted us a bigger plan and never mentioned the flood rule. HomeRise brought it up before we spent a dollar on design.