Fillet beads seal the angle between a window frame and a wall, flashing and masonry, or two panels meeting at a corner. The two bond faces meet at the root, so any movement between them concentrates strain in the corner, and a plain fillet takes far less movement than a butt joint built over backer rod. Bond breaker tape in the corner and a generous, concave-tooled bead buy back some stretch.
Run a fillet joint at the frame-to-sill corner, but that's a weatherseal, not a substitute for the sill pan.
Also heard as
- fillet bead
- angle joint
Related terms
Bridge joint
A band of sealant laid over the face of a joint, bonding to the surfaces on either side instead of filling the gap.
Tooling
Pressing and shaping freshly applied sealant with a tool to force it against the joint faces and give it a neat profile.
Sill pan
A tray of flashing under a window or door with a raised back and ends, catching any water that gets past the unit.
Movement capability
How far a sealant can stretch and compress, as a percentage of joint width, while keeping its seal.