Hello,
Could someone please assist me in determining if the crack in the multiple panes of this window was caused by thermal stress? I can't see it being an impact crack due to the fact that it seems to originate from the edge of both pains... I appreciate any and all help .

Picture: imgur: the simple image sharer

Thanks!

 

Can't offer much advice based on the picture. We can see the glass is cracked, that's about it. Can't tell if it's single pane glass or double pane (is it broken on the inside, but not on the outside?) and since it's a closeup, we can't really see where is is broken in relation to the rest of the window.

Glass is usually supposed to have some space around the perimeter of the edge so that any expansion and contraction will not put pressure on the glass. If the glass was tight inside the frame with no room for expansion and contraction then, yes, I would say that's the likely suspect. Things shrink in cold weather, so that could be the cause. Breaks that come from the bottom of a window during the winter is usually from condensation that turns to ice. Water expands when it freezes, so sometimes that will crack the glass. But like I said, that usually happens on the BOTTOM of the window, not the sides.

I'd suggest you put some duct tape (or similar) across the crack so that shards of glass will not splinter off when the glass moves and get in the carpet or in your socks.

 

I am pretty sure it is single pane and also each glass square is an individual pane. Additionally, a pane below is cracked as well. This is actually for a landlord-tenant dispute from a past occupancy. My thoughts are how can this damage not be due to thermal damage considering multiple panes are damaged and the cracks start in a perpendicular manner from the edge of the glass?

 

Those don't appear to be thermal breaks, but like XSleeper noted it is difficult to tell much from the picture.

 

Oberon, for what reasons does it not seem it? Thanks guys, really appreciate it.

 

A side impact on the muntin between the panes would crack it, especially if that's where the glazing points are located. Glazing points are installed here and there around a pane of glass to act as a temporary "stop" to hold the glass while it is being glazed, or while the interior stops are being installed. In an impact, the glazing points become the pressure point. The edge of the glass is the weak point where fractures begin.

For all we know, a big bird could have flown into it and cracked it. Is there any sign of impact on the exterior from a vandal? A dent in the wood, for instance? Any branches come off a tree?

If this is a double hung window, slamming the window could also cause it to break. Such as if someone opened it... and gravity caused it to suddenly fall shut on its own.

 

I think that XSleeper made some really good points in his reply. I would be really curious to see if the breaks occurred right on top of glazing points.

Based on your picture, it simply isn't possible to determine if the break pattern is consistent with thermal stress.

Glass is actually a poor conductor of heat and thermal breaks occur when there is a temperature differential in the glass such as might occur when a window that is partially in full sun and partially in shade. The difference in glass temperature between the sun-exposure and shaded part of the glass will cause stress in the glass that can result in breakage.

Thermal breaks do occur from the edge of the glass and head inward. Also thermal breaks stay away from corners as well. But they do have very specific patterns and from your picture I am not seeing that type of pattern. If you could post additional pictures, especially close ups where the breaks come out from under the muntin bars, they may be helpful?

 

I wish I could, but this is the only picture the landlord gave me. This window is actually not able to be opened and the outside portion is inside a screened in porch that is shaped:

Outside (screen)
Window is left side -> |_| <- Brick wall
Inside

On the inside of the side of the window is a couch that prevents anyone from really contacting the window which is about shoulder height. Additionally, no one really went into the patio and I think it would take tremendous force to break with impact in that way.

I really have no idea how an impact could have occurred but I do recall hearing glass breaking last winter and could not find where it came from.