Q: Our home, built in 2001, had what appeared to be "settling cracks" in the drywall — one on the main floor and the other in an upstairs...

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Q: Our home, built in 2001, had what appeared to be “settling cracks” in the drywall — one on the main floor and the other in an upstairs bathroom.

The first one runs at an angle from the corner of a “dropped” ceiling line to the corner of a nearby window, a distance of about 2 ½ feet.

The upstairs crack is about 8 to 10 inches from where the ceiling line for a skylight meets the “normal” ceiling line. These two ceiling lines in the bathroom were never aligned properly with the upper portion set back a fraction of an inch, which probably contributes to the problem. We had the builder repair both cracks before we moved in and then again just before the first-year warranty expired.

After a fairly short period of time, they were repaired again last summer. That process included scraping out the old patch, remudding, taping, drying and then painting again.

They’re back again less than a year later! Is there something that’s not being done correctly? Are we doomed to do this repair on an annual basis? Will this impact our ability to sell our home?

A: Drywall cracks show up routinely in only a few specific areas in newer homes:

Vertical and horizontal cracking on walls represents only normal post-construction wood-framing drying and shrinkage (and/or poor finishing technique). These are the seams in the sheets of drywall, manifesting as cracks. One repair after a year of the house seasoning, using the techniques you describe, and they should be taken care of permanently.

If wall cracks are extremely large, jagged and/or on 45-degree angles, then you have true “settling” issues. These are telegraphed images of framing problems or foundation issues behind and below. They will always be accompanied by “nail pops” and other signs of significant drywall shear movement.

These cracks may or may not get worse, and need to be investigated case by case. As you can imagine, these can be serious. They are rare.

Where ceilings are pulling away from interior partition walls on top-floor levels, leaving long horizontal cracks at the joint between ceiling and wall, 9 times out of 10 it is a roof truss issue.

This will come and go rapidly depending on weather. The roof framing actually lifts off the top of the wall slightly (they are not connected and float over the wall), cracking the drywall. The truss bracing schedule the engineers designed may not have been rigorously followed by the framers, and the moisture content difference between the top and bottom of a truss can be extreme. Lacking a few key 2×4 braces, the bottom of the trusses may tend to swing laterally or suffer from rogue lifting.

Extreme cases require truss engineer review. Caulking is the best solution for these smaller cracks. During original construction, floating corners utilizing drywall clips help prevent future cracking.

Hallways, skylights, dropped ceilings and other protrusions into an otherwise larger drywalled area or room can act like a lightning rod for cracking, as you can attest to. Older houses most commonly show this at the start of a hallway and around windows and doors, newer houses in skylights and stairs. Go ahead; find a house that doesn’t have drywall cracking in these areas — it’s rare.

Since this is and has been such a vexing problem, it needed definitive attention. In 1997, the Drywall Finishing Council found in an extensive study under laboratory conditions that drywall cracking is a result of relative humidity changes greater than 50 percent, with very little temperature correlation. Wood and gypsum expand and contract roughly equally to temperature changes, but not humidity (wood moves more). High desert locations are most vulnerable to these huge swings, and they consequently have the biggest cracking issues.

In your home, the movement experienced by an entire 30-foot-wide wing of the house is brought to bear in a small 8-to-10-inch space between the wall and skylight shaft, or at the start of the hallway in an older home. This will crack every time, and it’s not the drywaller’s fault. It is simply the unfortunate conjunction of two adjoining surfaces in a small area.

Concrete cracks the same way. Look for the protrusion or corner, and you will find the crack.

Different portions of a home move at different rates and in different directions. Despite all the engineering and shear resistance built into a new home, they will move slightly in windstorms and earthquakes, and an even greater amount of expansion/contraction is experienced simply as the weather changes.

The cracks you see are the fault lines of the ceiling. And you have two San Andreas-sized faults — one on each floor, unfortunately. This does not mean the house will be difficult to sell.

And yes, they will recur.

What you need is a siliconized latex caulking in the cracks. Silicone provides the extreme flexibility, and the latex adds the paint-ability. Scour out the loose debris, caulk it and paint it.

If the crack is too large to successfully caulk and have it look respectable, have the builder try “hot mud.” It is much better at resisting cracks than finish mud, especially in repairs. Good luck!

Darrell Hay is a local home inspector and manages several rental properties. Send home-maintenance questions to dhay@seattletimes.com. Sorry, no personal replies.