Key takeaways
- Retrofit fits a new window inside the existing frame. The stucco or siding outside stays untouched.
- New construction removes everything down to the studs, then rebuilds and waterproofs the opening.
- Most East Bay replacements are retrofits. New construction is for rot, leaks, resizing or remodels.
- Both must meet California’s Title 24 energy rules, and many need a permit either way.
What is the difference between retrofit and new construction windows?
A retrofit window (also called an insert or pocket window) is installed inside the existing window frame. The old glass and sashes come out, the old frame stays in the wall, and the new window is fitted, sealed and trimmed inside it.
A new construction window (also called full-frame) replaces everything: glass, sashes, frame and trim come out down to the rough wall framing. The opening is repaired and waterproofed, and the new window, which usually has a nailing fin, is installed and flashed into the wall.
How does a retrofit installation work?
- We remove the old sashes and glass, and on aluminum sliders, cut away the parts of the old frame that stick out.
- The new window, made to the measured size, sets into the old frame. In California stucco homes this is often a window with a flat flange that covers the old frame edge from outside.
- We level and secure it, insulate the gaps, and seal it inside and out.
- Interior trim is finished, and the outside looks clean without touching the stucco.
How does a new construction installation work?
- We remove the entire old window, including the frame, down to the studs.
- Any rot or water damage in the framing is repaired.
- The opening is waterproofed with flashing so water is directed out, not into the wall.
- The new window is installed, flashed and sealed.
- The exterior around the opening, such as stucco, siding or trim, is patched and finished, and the interior is trimmed.
Retrofit vs new construction: side by side
| Retrofit | New construction | |
|---|---|---|
| Exterior stucco or siding | Untouched | Opened, then patched |
| Time per window | Faster | Longer |
| Relative cost | Lower | Higher |
| Glass area | Slightly smaller than the old opening | Full size of the opening |
| Fixes hidden rot or leaks | No | Yes |
| Can change window size | No | Yes |
| Best for | Sound frames, most stucco homes | Damage, leaks, resizing, remodels |
When is retrofit the right choice?
When the existing frame is solid, square and not leaking. That covers most East Bay homes, including the 1950s to 70s ranches in Concord, Pleasant Hill and Walnut Creek with their original aluminum sliders, and newer homes whose builder vinyl has simply worn out. Retrofit is faster, costs less and avoids patching and repainting stucco.
When do you need new construction windows?
- The frame or the wall around it is rotted or water damaged
- The window has been leaking into the wall
- You want to make the opening larger, smaller or a different shape
- You’re already remodeling and the walls are open
- The old frame is so out of square that an insert can’t seal properly
What about stucco homes in the East Bay?
Stucco is the main reason retrofit is so common here. Cutting stucco back for a full-frame install means patching and usually repainting, and matching old stucco texture and color is never perfect. With a sound frame, a retrofit gives you all the benefits of the new window and leaves the stucco alone.
Many homes end up with a mix: retrofit for most windows and new construction on the one or two that show water damage, which is usually the side that takes the weather.
Do permits and Title 24 apply to both?
Yes. California’s Title 24 energy standards apply to replacement windows either way, and many cities require a permit for window replacement regardless of the method. New construction can involve more inspection because the wall is opened. See our guide to window permits in Contra Costa County.
How do we decide for your home?
At the estimate we check every opening: whether the frame is solid and square, whether there are signs of leaks or rot, and what’s outside the wall. We recommend retrofit wherever it will perform properly, and we explain any window that needs new construction before anything is ordered. We won’t upsell you to a more invasive method when a simpler one will do the job.
Want a straight answer for your home? We’ll look at your windows and tell you what they need, even if that’s nothing yet.
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