New Construction vs. Replacement Windows: What's Different and What Isn't

Homeowners doing research on window replacement often encounter two categories of product: new construction windows and replacement windows (also called retrofit or insert windows). The terminology can be confusing. Here's exactly what the difference is and why it matters.

New Construction Windows

New construction windows include a nail fin — a flanged extension of the frame that laps over the exterior sheathing and is fastened directly through it into the wall framing. The fin becomes part of the weather barrier of the wall, overlapped by the house wrap or stucco.

New construction windows are used when:

• Building a new home (obviously)
• Doing a major renovation that removes exterior siding or stucco down to the sheathing
• The existing window frames need to be removed entirely due to rot or damage, requiring the full rough opening to be exposed and re-weatherproofed

Replacement (Retrofit) Windows

Replacement windows are designed to install inside an existing frame, without removing the exterior casing or disturbing the exterior wall surface. The new window frame installs inside the "pocket" left by the removed sash and glass. This is the method used for the vast majority of residential window replacements in Florida.

The advantages are significant:

• No exterior stucco or siding repair required
• Less disruption to the home's interior and exterior finish
• Faster installation (a trained crew can replace a window in an hour or less)
• Lower overall project cost when the existing frame is in good condition

When the Frame Has to Go

Replacement windows are only appropriate when the existing frame is structurally sound and free of rot, moisture damage, and corrosion. If we find that the existing frame has problems during our assessment, we'll tell you — and the project may need to move to a new construction approach, with corresponding adjustments to scope and cost. This is rare but it does happen, particularly in older homes or those near the water.

What You Get Either Way

Whether we're doing a new construction or replacement installation, the requirements for impact rating, anchoring, and sealing are identical — and our work meets Florida Building Code for both. The end result in terms of storm protection, energy performance, and appearance is the same.