The Brooklyn townhouse project we’re following is a cutting-edge application of the latest energy-efficient technology. Structurally, however, it’s old hat—at least if you’re New York City structural engineer Kathy Dunne, who has been working on brownstones for three decades, or Brooklyn contractor Jose Maldonado, who has been renovating brownstones for twenty years.

But if you’re not that accustomed to working in 100-year-old brick row houses, the project offers a few interesting structural wrinkles. In this set of photos, we take a look at the way the framers reinforce the old, sagging floor joists with new steel framing and engineered lumber, tie that new structural work into the existing brick bearing walls, and beef up the roof structure to handle a whole new set of loads from a rooftop patio and access bulkhead.