Question 1

Replacement windows vs. new-construction windows: what's the difference?

Accepted Answer

Replacement (insert) windows fit inside the existing frame — faster, less expensive, and a good choice when the existing frame is square, sound, and properly flashed. New-construction (full-frame) windows replace the entire assembly including the frame and exterior flashing — necessary when the frame is rotted, when you're changing the window size, or when the original installation was improperly flashed. In homes with known water-intrusion history, full-frame replacement with new flashing is the safer investment.

Question 2

Why does window flashing matter?

Accepted Answer

A premium window installed with poor flashing will leak. A mid-grade window installed with proper flashing will not. The flashing system — sill pan, jamb tape, head flashing, and integration with the weather-resistive barrier — is what keeps water out of the wall cavity. Sill pan flashing at the bottom of every opening is the most critical, as the sill is the most common leak point. Head flashing must lap over the weather-resistive barrier so water sheds down and out, never behind it.

Question 3

What causes water intrusion around windows?

Accepted Answer

The most common cause is improper or missing flashing. Water gets behind the weather-resistive barrier at the window opening and travels into the wall cavity. Proper flashing — sill pan flashing, jamb flashing, and head flashing integrated with the WRB — directs water back out. Failed sealant at the window-to-frame joint and missing or inadequate insulation that allows condensation are also common causes.

Question 4

When should windows be replaced?

Accepted Answer

Condensation or fogging between the panes means the seal has failed and the insulating gas is gone. Drafts, difficulty operating, rotted wood frames, water stains on the sill or drywall below, and increased energy bills are all indicators. Single-pane windows in any California home should be replaced — they're a major source of heat gain in summer and heat loss in winter. Each window should be assessed individually; replacement is recommended only where needed.

Question 5

Does window replacement require a permit?

Accepted Answer

In most jurisdictions, replacing windows one-for-one (same size, same type) does not require a permit. However, enlarging a window, changing its type, or changing egress windows typically does. Replacement windows may also be subject to applicable California Energy Code requirements depending on the project, location, and compliance path — the specific glazing performance values should be confirmed for your installation rather than assumed. Always verify requirements with your local building department.

Question 6

What should homeowners consider when selecting replacement windows?

Accepted Answer

Beyond style (casement, sliding, double-hung, fixed), consider the frame material (vinyl, fiberglass, wood-clad, aluminum), glazing performance (U-factor, Solar Heat Gain Coefficient, low-E coatings), and whether the window meets Title 24 energy requirements for your climate zone. Sound transmission class (STC) matters near busy streets or the ocean. Egress requirements apply to bedroom windows — they must open wide enough for emergency exit. A contractor should measure every opening and verify square, level, and plumb before ordering.

Question 7

What happens during window replacement?

Accepted Answer

For insert (replacement) windows: the old sash is removed, the existing frame is cleaned and inspected, the new window is set in sealant, shimmed level and plumb, insulated with low-expansion foam, and trimmed. For full-frame (new-construction) windows: the entire old window and frame are removed, the rough opening is inspected and repaired, sill pan flashing is installed, the new window is set, flashed at jambs and head, integrated with the weather-resistive barrier, insulated, and trimmed. Each window takes 1–3 hours depending on type and condition.

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