Cracked wall

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  #1  
Old 01-30-17, 11:41 PM
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Cracked wall

Hello, couldn't decide which forum to use, hope this is the right one. Somewhat of a drywall question I guess... I have had a wall that cracks, and would like some input.

Background: Factory built trusses, house is about 10 years old. I have lived here a couple years. This guy built both my house and neighbors house nearly identical. He was not really a great builder, and it shows in places. Used bare minimum of everything including drywall thickness. Both these houses have the same crack. The living room has a vaulted ceiling with scissor trusses. Small insulated attic above the living room trusses, not a cathedral. The rest of the house has a conventional truss. Insulation is about R30. Going to blow in more cellulose when I get this crack figured out.

The drywall was repaired by professionals hired by the previous homeowners, by the homeowners themselves, and the neighbors also have tried multiple things to fix the crack (drywall, not structure). Neighbors say this crack has happened basically since new, they purchased while house was under construction or shortly thereafter.

The crack is seasonal. This time of year, Michigan, below freezing temps, the crack is probably nearly 1/4" wide. In summer, no crack at all. The drywall is cracked both horizontal at bottom truss chord, and vertical where truss is trying to compress drywall toward roof. Crack is much worse horizontal. It has even popped a couple drywall screws further down toward the floor and cracked in the corner of kitchen ceiling near this crack in the wall. See pictures of crack below.

I think one of two things is happening. Either the truss has "truss uplift" and they didn't account for it somehow, OR the way they tied the truss to the other structure is making it twist/distort somehow.

The only thing I see that I question is they cross braced the top of scissor truss where the crack is happening to the bottom chord of the next over conventional truss, probably for shear. In the picture, the brace is just one stud bay down the center hallway. I would think that it should have been top chord to top chord, or at least something different as the brace is very short and it goes at a 45-ish degree angle to the next truss over. I wonder if this is racking the truss in question enough to crack the drywall?

No other apparent structural issues. Nice solid poured concrete foundation (nice dry basement) and no other places in house where there are cracks. No apparent moisture or roof issues either. All interior and exterior doors and windows open and close fine, so I don't think it is settling issue. We aren't in seismic zone or anything like that. No sagging roof or unlevel floors. Too temp related, and two houses doing same thing so must be either design issue, or something guy did when building.

Thoughts? Anyone seen anything like this? Fixes?
 
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  #2  
Old 01-31-17, 05:22 AM
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I can assure you that if your trusses are from the last 15+ years they did account for "uplift" though I don't think that's the problem. Depending on your wind zone your house may even have additional metal strapping (hurricane straps) further attaching your trusses to the outer load bearing walls.

Most trusses are designed so all the load bearing is done at the outer walls. The interior walls of your home likely are not structural and are only there as room dividers. As such the engineering and installation instructions often do not call for the interior walls to be attached to the trusses. I have even run into inspectors who specifically do NOT want interior walls attached to the trusses because it's not specified in the engineering. Without the interior wall firmly attached to the truss both structures can move independently of each other. It's not much movement but with seasonal humidity and temperature changes there can be enough movement to crack sheetrock.

Before you attempt another sheetrock repair I would get in the attic and shovel the insulation away from that area. You could pilot drill and screw the wall top plate and truss together. You could also use steel angle brackets available from most home centers and lumber yards. Then once you have things nicely tied together attack the cosmetic crack.

It's a tough location and is made worse when the rock hangers put a joint between panels there (and they almost always do). Remove the old sheetrock joint tape. There is heavy duty joint tape. Not the yellow open mesh stuff you see in the home center but it's a special heavy duty tape that has it's fibers running in both directions for greater strength and crack resistance. You can install it with a proper film of mud underneath or I like to go a little crazy and stick it on with a thin film of wood glue. Then finish and paint normally.
 
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Old 01-31-17, 08:29 AM
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It's a tough location and is made worse when the rock hangers put a joint between panels there (and they almost always do).
This is exactly the problem. The drywall should have been hung to span that joint, with no fasteners used in the area that spans the joint, to allow for slight movement. IMO the repair would cut out a 4' section... 2' above the crack and 2' below the crack... so that one solid piece could be installed over the area.

An alternative would be to install an expansion joint. Common in commercial work... usually ugly and unsightly in residential work.
 
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Old 02-01-17, 11:14 PM
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I can see where attaching truss to top plate would help this crack, but I was afraid it might transfer the force to somewhere else and create a different issue. I agree with the poor drywall install, like I said above they used the thinnest possible drywall. It is 1/2" or maybe 1/2" lighweight. It sure scuffs and marks up easily and if you even touch it around an electrical box it crumbles.

My previous house built in the late 60s was much better constructed in general. It had 5/8 on the walls and you could sure tell the difference!

So with that thought in mind, (and maybe this goes to the drywall forum?) is there a way to "float" new drywall over that wall? This sounds wrong when I think about it, but could you somehow not screw the new layer down (in certain areas) and let it expand somewhere or somehow... I am talking leaving the old and adding another layer. Attach with an adhesive or resilient channel? Put the expansion joint at the ceiling where maybe it would be less noticeable there than in middle of wall???

Unfortunately the height is wrong to hide with molding unless I got some 4-5" tall stuff and even then it might look weird where it intersects the kitchen. Maybe I'll just hide it all with 70's style false beams. I actually don't mind that look.
 
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Old 02-02-17, 03:59 AM
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1/2" drywall is the norm for walls .... and for ceilings IF the framing is on 16" centers. About the only time I've seen 5/8" drywall used on walls is when a fire wall is mandated. Years ago some of the cheap houses would use 3/8" drywall on walls

You can laminate over the drywall with another layer but it will change a few things. Your base board and any other wood trim will need to be modified to fit the now slightly smaller room. Also any electrical outlets will need box extenders. Personally I'd go with X's suggestion and cut out the drywall below/above that joint and install one piece of new drywall.
 
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Old 02-02-17, 05:18 AM
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I think adding another layer of sheetrock will be a lot of work. To work best you would glue the new sheetrock onto the old but adhesion will be reduced by the paint on the existing wall. You would also have to figure out how you want to finish off the edges where the kitchen is and the arches for the hall and other room. You would also have to tape and finish the corners at the ceiling and adhesion for the new tape would not be good with the painted ceiling. A lot of work for something that may cause problems elsewhere.

If you want a really easy fix just cover the crack with a strip of molding.
 
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