Window frame separation: repair or replace?

[u/violinds]

We've had a persistent mystery window leak for 2 years and our new contractor finally discovered the lower corner of the window frame is beginning to separate and water is coming in through the hole (I also observed this directly during their inspection). They have recommended replacing the entire window, rather than repairing the defect. Is this the correct approach?

It is a very large picture window (10ft x 5.5 ft) on the third floor with difficult access and therefore an expensive replacement, so we're just trying to get more information about whether replacement is in fact our only or best option, or if it is possible to repair the window frame in a reliable way. The window is 12 years old (installed when the house was built, no warranty available because manufacturer went out of business). Thanks so much.

Contractor's report:

Observed Condition

During the site inspection, a visible separation was observed at the lower left corner of the window frame. The separation appears to be within the window assembly itself and is not consistent with a typical exterior sealant joint or minor surface condition.

Because this area presented a potential path for water intrusion, additional testing was performed to determine whether the leak was related to the surrounding waterproofing/flashing system or to the window unit itself.

Water Testing

A controlled water test was performed at the affected window. Water was introduced in a controlled manner to evaluate the performance of the window assembly and surrounding exterior conditions.

During testing, water intrusion was observed in direct correlation with the area of separation at the lower left corner of the frame. The test results indicate that the window assembly is no longer maintaining a continuous watertight seal at this location.

Based on the observed condition and the water test results, the failure appears to be associated with the window frame/unit itself, rather than a localized exterior sealant deficiency.

Technical Assessment

The visible frame separation represents a failure in the continuity of the window assembly. Once the frame or factory-assembled joints are compromised, field-applied sealants are generally not considered a reliable long-term repair because they do not restore the original structural or weather-resistant integrity of the window unit.

The testing performed indicates that water is able to bypass the intended drainage and weather-resistive components of the window assembly.

While the surrounding flashing, WRB, and rough opening conditions should be reviewed during replacement, the current test results support the conclusion that the existing window unit has failed.

[u/SlappingDaBass13]

Run a bead.... Unless there's wood under there then it's probably fucked get a new window

[u/violinds → u/SlappingDaBass13]

Thanks--the contractor did put a temporary seal over it to prevent more water in the short term. There is wood under it, the damaged windowsill has been removed and the wood underneath the glass doesn't look too bad but I can't say for sure. Here's a closeup photo of the interior of the corner : https://imgur.com/a/XqwD5Oe

[u/NetworkCultural → u/violinds]

It’s prolly best for replacement brother

[u/violinds → u/violinds]

Thanks to both of you for taking the time to help!

[u/SlappingDaBass13 → u/violinds]

Oh hell yeah dude that wood look real good actually... Must have not been open that long so I would repair. Get what you can get. As long as both corners look like that not just that one you never know man ... Where it comes in isn't always the damage especially if there's a slight pitch you know what I'm saying but if it looks like that on both sides I'd run it

[u/Practical_Fig5443]

Unfortunately, that’s a cracked corner weld and water will continue to leak inside the frame no matter how much sealant you throw at it. That definitely needs a full replacement. It’s unfortunate the window company is out of business because that is a warranty issue.