How to Measure for Replacement Impact Windows

Three dimensions get confused constantly. The rough opening is the structural hole in the wall — concrete block in most South Florida houses, framed lumber in others. The frame size is the outside dimension of the unit itself. Many Florida openings also have a buck: a wood or aluminum sub-frame fastened to the masonry that the window is anchored to.

Catalog sizes in the PORTELA 11 store are frame sizes. A unit must be slightly smaller than its opening so the installer can plumb, shim and seal it; how much smaller depends on the product, the buck and the installer's method. When you send measurements, say what you measured — the inside of the existing frame, the masonry opening with the old frame out, or the face of the buck — so the number is interpreted correctly.

Replacement products (equal-leg or flush-fin, depending on the brand) have a flat frame that sits inside the opening and is anchored through the frame into the buck or masonry. New-construction products have a nailing flange fastened to the outside face of the wall before stucco or siding goes on.

In an occupied house with the stucco in place, replacement frames are the usual choice because the exterior finish stays closed. In a new build, an addition or a full re-stucco, flange frames are common. The two are not interchangeable, and the NOA or Florida Product Approval lists the installation types a series is approved for. If in doubt, photos of the opening from outside and inside tell the story.

For doors, also note the height from the finished floor or threshold and whether a sidelite or transom shares the opening. For sliding glass doors, measure the full width the whole unit will fill, not one panel.

• Use a steel tape and measure in inches to the nearest 1/8. Write fractions the way the trade reads them: 36 3/4, not 36.75 or 3 feet.
• Width: measure at the top, middle and bottom. Height: at the left, center and right. Openings are rarely square; the smallest number controls.
• Measure every opening separately, even when they look identical; block houses vary by half an inch or more.
• Write width first, then height: 37 x 50 1/2 means 37 inches wide by 50 1/2 inches tall.
• Note anything unusual: a sloped stucco sill, an arched top, a mullion between two units, a security bar bracket, an air conditioner sleeve.
• Photograph each opening inside and outside with the tape visible, and label the photos to match your list (for example Bedroom 2 — east wall).

The letters describe which parts move: X is an operable panel or sash, O is a fixed panel. Codes are read from outside the building, left to right, as most manufacturers and approvals do.

Conventions vary slightly between brands, so write the code and add a plain sentence — for example: standing outside, the left panel slides open.

• XO: a horizontal rolling window or sliding door whose left panel (seen from outside) slides. OX: the right panel slides. XX: both slide.
• Single hung: the lower sash moves; no handing code is needed, but state equal-lite versus oriel (unequal) layouts.
• Casement: XL or XR (some brands write LH / RH) for a sash hinged left or right as seen from outside; XL/XR also marks the active panel in some door charts.
• Sliding doors with three or four panels: OXO, OXXO, XOX and similar; say which panels must open and toward which side.
• French and outswing doors: specify the active leaf (left or right from outside), inswing or outswing, and single or double.

Send the list by WhatsApp to (786) 590-0488 or by email to sales@portela11.com. Matching stock sizes can be ordered directly; openings between standard sizes are reviewed for alternatives or special order. Measuring for a quote is not the installer's final field measurement, which should happen before a non-returnable special size is ordered.

• One line per opening: location, quantity, width x height, product type, configuration.
• Frame color (white or bronze), glass (clear, gray, Low-E) and privacy option, if any.
• Replacement or new construction, and whether a buck is present.
• Design pressure required, if your engineer or permit has stated it.
• Project ZIP code, and whether you will pick up at the warehouse or need a delivery quote.
• Photos of the openings, labeled.