Rainscreen Shingle Siding for a Coastal Dormer
Painted wood shingles and clapboards are a traditional siding material in many regions, including coastal New England. But in the rough climate of a Maine island, durability is a concern. For a custom gut-rehab of an old vacation cottage, Peaks Island, Maine, design/build contractors Thompson Johnson Woodworking decided to give the home's new wood exterior its best odds of long-term durability and trouble-free performance by installing the siding over a vented air space — a classic rain-screen siding system.
JLC's Coastal Connection newsletter has been following the job since last winter, focusing on structural challenges and high-performance energy details. But now that summer is here, the team has moved on to exterior finish details. This month, we visited the job to see project lead Mark Pollard and his crew perfect their rain-screen application.
On an earlier visit, we took a look at the rain-screen details for the clapboard siding on the home's main story. Those walls had three inches of foil-faced polyiso insulation, with wood strapping applied over it to create the rain-screen air gap and provide nailing for the horizontal siding. But on the upstairs dormers, there's no foam insulation and no clapboards — instead, the crew applied asphalt felt paper over the tape-sealed ZIP System OSB sheathing, then followed with Mortairvent rain-screen fabric before nailing on pre-primed and factory-dipped white cedar shingles (photo below). For a step-by-step walk-through of the process, see the slideshow.
Project lead Mark Pollard nails factory dipped white cedar shingles over 3/8" MortairVent drainable fabric. Shingles are held 1 inch above the flashing and roofing to promote drainage and to allow an inlet for air into the rain screen assembly.