How to Install Exterior Siding Over House Wrap

Siding acts as the final line of defense against the elements, but its true performance depends on what lies underneath. When you install your exterior finish over a properly applied house wrap, you create a building envelope that breathes while shielding the structural framing from moisture infiltration. Done well, this setup allows for the necessary drainage and airflow required to prevent rot and mold behind the wall surface. Success in this project hinges on precision and sequence. You must respect the integrity of the house wrap during installation, meaning every nail hole and board overlap must contribute to the shedding of water, not the trapping of it. Once the wrap is secured, the siding goes on to provide the aesthetic finish and the primary wind barrier, turning a house frame into a finished, weatherproof home.

  1. Seal Every Wrap Breach. Examine the installed house wrap for any tears, punctures, or loose seams. Repair small holes with construction-grade flashing tape and ensure all joints are overlapped in a shingle-fashion so that water flows downward over the seams.
  2. Build the Breathing Gap. Attach vertical furring strips to the wall studs over the house wrap to create a rainscreen gap. This space allows for moisture evaporation and prevents the back of the siding from sitting directly against the moisture barrier.
  3. Get Perfectly Level First. Level and install the starter strip at the lowest point of your wall. This strip is critical because it dictates the levelness of every subsequent row of siding above it.
  4. Fasten With Flex in Mind. Snap the first course of siding into the starter strip and fasten it through the nailing flange. Use galvanized or stainless steel nails, leaving a slight gap between the nail head and the siding to allow for thermal expansion.
  5. Seal Every Opening Tight. When you reach windows, doors, or exterior outlets, trim the siding panels to fit snugly. Flash around these gaps using adhesive flashing tape to ensure the house wrap remains sealed to the trim elements.
  6. Trim and Seal Smart. Install corner posts, J-channels, and finish trim to conceal raw edges of the siding. Apply a high-quality exterior sealant along the joints where siding meets trim to prevent water ingress.