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Need help with jambs?

The finishing touch that frames your view.

An interior jamb—also known as a jamb extension—is the trim component that bridges the gap between your window or door frame and the interior wall surface. It forms the visible interior edge of your window or door, offering a clean, finished look while allowing for proper installation and insulation.

Whether you're finishing a new build or upgrading existing openings, an interior jamb is essential to creating a professional-grade installation that looks polished from the inside out.

Why Use Interior Jambs?
  • Finishing Detail: Interior jambs cover the rough opening between the window or door frame and the drywall or wall finish, providing a smooth transition.
  • Structural Fit: They accommodate different wall thicknesses, ensuring the window or door sits flush with the interior wall.
  • Insulation Support: They help secure insulation between the window/door frame and the surrounding wall for better energy performance.
  • Design Cohesion: Available in multiple materials and styles, interior jambs allow homeowners to match or contrast with interior finishes.
When to Use Interior Jamb Extensions
  • When the wall depth exceeds the window or door frame depth
  • During new construction or full-frame replacement installations
  • When a clean, flush interior finish is required
  • To match or accent interior decor with painted wood or vinyl options
Types of Jambs

At IRIS, we sell two types of Jambs for Windows & Doors: PVC Jam Extensions, and Primed Wood Jamb Extensions.

How to Choose the Right Jamb Extension
  • If you want a low-maintenance, moisture-resistant option - especially for kitchens, bathrooms, or modern white trim - go with PVC jamb extensions.
  • If you're looking to match existing wood trim, customize the paint colour, or want a more traditional feel, primed wood jambs aer a better fit.

Both options offer a clean, professional finish—it just depends on your style and needs.

PVC Jamb Extensions

Designed to complement your Iris vinyl windows, these are maintenance-free and made from 100% vinyl for long-lasting performance. Ideal for moisture-prone areas like bathrooms and kitchens. 100% maintenance-free with a clean white finish.

Available Sizes:

Vinyl Jamb 1 - 3/8”
Vinyl Jamb - 1-3/8" 		Vinyl Jamb 1-7/8”
Vinyl Jamb - 1-7/8"
Vinyl Jamb 2 - 3/8”
Vinyl Jamb - 2-3/8" 		Vinyl Jamb 3 - 3/8”
Vinyl Jamb - 3-3/8"
Vinyl Jamb 4 - 5/8”
Vinyl Jamb - 4-5/8"
Primed Wood Jamb Extensions

A classic, customizable solution for finishing your window and door interiors. Our primed wood jamb extensions are designed to be paint-ready—making them ideal for homeowners or installers who want to match existing trim or create a custom interior look.

These extensions offer the natural strength and warmth of wood while providing the flexibility to blend seamlessly into any décor.

Available Sizes:

Jamb 2 - 3/8”
Primed Jamb - 2-3/8" 		Jamb 2-5/8”
Primed Jamb - 2-5/8"
Jamb 3 - 3/8”
Primed Jamb - 4-5/8" 		Jamb 4 - 5/8”
Primed Jamb - 3-3/8"