cracked ceiling at scissor truss (single-wide trailer)

[PSUengineer1]

Hi all,

Thanks for reading, please see attached pictures.

Single wide trailer with a ceiling crack across the entire 14' width. Crack is parallel to a partition. Considered snow load as culprit but not enough snow to cause damage to a competent structure. Could the damage shown in the attached pics be due to truss uplift? The term truss uplift refers to flexing of the roof trusses caused by differences of moisture content and temperature between the top and bottom chords of the trusses. the crack occurred in the winter, so it makes sense that the lower truss chords that touch the warm ceiling dried out and shrank during the heating season, while colder upper chords gain moisture and expanded. maybe the drywall ceiling was attached to a nailer, which is attached to the wall and truss... so when the truss moved upward it took the nailer and drywall with it? I am taking guesses here, really need to demo it to see the details. Any best guesses or theory challenges are appreciated.

Thanks.

 

[dik]

One of the features of wood factory fabbed trusses is that they can move upwards with changes in humidity. Could this be the issue? You do not want to connect the ceiling immediately near an interior partition for this reason. Check into truss uplift... may be an issue.

Dik

 

[XR250]

I can't imagine thermal/moisture differentials to be an issue on a 14 ft. span truss. It's a single wide - could be anything! This should be the least of the homeowners worries! They are long and skinny. Settlement of the crappy, no footing piers that are typically installed could cause this. Perhaps longitudinal thermal expansion/contraction of the entire structure?

 

[r13]

Two questions: 1) Is the space above the ceiling insulated? 2) How the ceiling is attached, directly attached to the bottom chord of the joists?

I guess the joist has deflected, with shrink of the top chord, and lengthen of the the bottom chord. The guess is supported by observing the width of the crack, which is quite wide, seemly thru push rather than lift. I agree that humidity and moisture are the culprits.

 

[oldestguy]

If you never have lived in a trailer, you don't know how cheaply they are built. Strong wind and they wiggle back and forth, Comes big storm go to a shelter or you get killed. I'd not worry about it, since it just not much of a structure. Re-paint and fill the crack.

 

[BAretired]

BA