MasterFit Trim Saves Time and Beautifies Windows

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Provia MasterFit Trim

Interior wood trim is an option that greatly contributes to the finished look of a window.  Decorative trim enhances a basic window, elevating the appearance of a room.

Interior wood trim covers the seam where the edge of the wall meets the frame of the window, obscuring the cut drywall behind it and closing off any gaps. Trim can also contribute to a window’s energy efficiency by working as a barrier, helping to keep outdoor air outside, and adding a layer of protection to the insulation around the window.

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Cutting and installing wood trim by hand can be time-consuming and costly. MasterFit Trim by ProVia® saves time and effort for contractors – it’s mitered casing with a high-quality mortise and tenon corner locking system that ensures a strong, custom fit, and a durable, long-lasting finish. MasterFit Trim comes complete with assembled frame extensions that interlock for strength.


MasterFit Trim can be configured three ways, depending on the contractor’s needs:

  • Pre-installed jamb extensions are clipped to the side of the window frame, and casing is assembled and packaged separately. Installation is a quick, 2-step process – the window is installed with the jamb extension attached, then the casing is attached and secured.
  • Trim is assembled and shipped loose – an ideal solution when windows are installed prior to drywall. The trim is cut to size and the jamb extension and casing are packaged together but separate from the window. The jamb extension is inserted and the window installed, then the casing is attached and secured.
  • Knock down – all trim pieces are cut to size and shrink-wrapped together. The installer assembles the jamb extension box and the casing, inserts the jamb extension and installs the window, then attaches casing and secures.

MasterFit Trim is ideal for installing windows when a home is being renovated and the interior walls may not be perfectly plumb – a jamb adjustment is included for a ¼” variation around the window, ensuring the trim will sit snugly against the wall.

Profile options include 2.5” and 3.5” Colonial, 2.5” Modern, and 3.5” Flat. It’s available in 14 stain finishes for either oak, cherry or maple wood, plus 16 paint finishes, all with a 10-year finish warranty.

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