Install Types & Frame Profiles
Block Frame & Flush Fin
A block frame is a finless, square-tube frame that drops into a prepared opening or buck and anchors straight through the frame into the masonry. It's the retrofit and masonry workhorse — no fin, so it doesn't depend on stucco or sheathing to hold. A flush fin is a retrofit profile with a small fin that laps flat against the existing exterior face or old frame, letting you re-skin a tired opening without tearing off stucco. Pick block frame when you're anchoring into a buck or block opening; pick flush fin when you're covering an existing frame and want to leave the wall finish intact.
- Block frame anchors: through the frame into masonry/buck
- Flush fin lap: small fin sits flush on the existing exterior face
- Shim gap: window + 1/2" inside the finished hole
- Stucco removal: none required for flush fin
- Block frame = finless tube. It seats in a Block Framed opening or wood buck and is fastened through the frame jambs/head, so the wall finish doesn't carry the window.
- Flush fin = block frame with a small applied fin. The fin laps the old exterior frame or stucco face, hiding the seam and weatherproofing the perimeter without demo.
- Flush fin is a Florida Flange / Replacement style move: the old frame stays in place and the new unit nests over it — fast turnaround, minimal patching.
- Block frame is the choice for New Construction into block or any Remodel where you've built a clean buck to anchor into.
- Either way the finished hole still follows the rule: window + 1/2" shim space. Get the buck and masonry opening right first (e.g. 36x60 window → 39.5x63.5 masonry opening → 36.5x60.5 finished hole).
Pros
- Block frame: anchors through the frame — strong, code-friendly hold in masonry/buck
- Block frame: no fin means it fits prepared openings cleanly with no stucco dependency
- Flush fin: re-skins a worn opening without removing stucco or the old frame
- Flush fin: fast, low-mess retrofit — minimal patching and finish work
Watch-outs
- Block frame: needs a properly prepped opening/buck before it can go in
- Block frame: anchors pass through the frame, so flashing and sealing the perimeter is on you
- Flush fin: the old frame stays, so you lose a little glass area / daylight opening
- Flush fin: only works when the existing frame is sound — rot or rust means full replacement