feathering strip
One of the tapered wood filler strips placed along the butt ends of old wood shingles to create a relatively smooth surface when reroofing over existing wood shingle roofs.
feathering strip: tapered shim for old shingle transitions
A feathering strip is a wedge-shaped piece of wood installed over the butt ends of existing wood shingles before laying a new roof. The taper gradually raises the plane of the roof surface, eliminating the step created by overlapping courses of old shingles. Without feathering, new shingles laid directly over worn courses would rock and gap, allowing water penetration and creating uneven fastening conditions. The strips are typically cedar or treated softwood, ranging from 1/2 inch to 1 inch thick at the high end and tapering to near zero thickness.
Feathering strips are most common in reroofing applications where existing wood shingle roofs are covered with new asphalt or wood shingles rather than completely stripped to bare decking. They are installed perpendicular to the roof slope, aligned with the butt line of each course, and face-nailed with corrosion-resistant fasteners before the new roof goes down. The strips follow the contour of the existing shingles, creating a gradual transition rather than sharp steps that would cause pooling and accelerated wear on new shingles.
Variants and installation challenges
Strip dimensions vary by the depth of the old shingles and the slope of the roof. Steeper pitches require more aggressive tapering to avoid creating a wrinkled or excessively thick transition. Installation demands careful fastening to the old shingles without driving fasteners through the sheathing into the rafter spaces, which can damage insulation or create moisture pathways. Improper alignment or incomplete coverage can result in new shingles cracking or curling where support is uneven.
The practice is now less common due to the prevalence of complete tear-offs, which allow roofers to inspect and repair underlying decking, verify flashing integrity, and eliminate the compounding problem of multiple roof layers. Building codes in some jurisdictions restrict the total weight of overlaid roofs or prohibit layering altogether. However, feathering strips remain the standard approach in renovation work where cost or structural considerations favor reroofing over removal.