Installation Details · FAQ

Why is step flashing better than continuous on walls and chimneys?

Continuous flashing is a single long piece of metal that runs the entire length of the wall-to-roof intersection. It looks cleaner during install but fails reliably within 10 to 15 years because the metal expands and contracts at a different rate than the wood substrate, opening micro-gaps along the joint.

Step flashing is a separate L-shaped piece for every shingle course, woven into the courses as they go down. Each piece is small enough that thermal movement doesn’t open the joint, and water hitting the joint sheds onto the shingle below rather than running along the wood. Trill installs step flashing on every wall and chimney intersection, even on retrofits where we have to peel back the existing shingles to do it right.