Diagonal Cracks Over Doorways

Question:

Hi,

I recently purchased a house, and within the first month, I've noticed diagonal cracks appearing in the sheetrock in the upper corners of the doorframes.  Some are substantial (a foot long) others are small, but upon closer inspection, it looks like someone had tried to fill them with plaster before applying fresh paint.

The house is 10 years old.  Should I be concerned about foundation issues?

Thank you...
Brent A.

Reply:

It's surprising how much drywall cracking is considered "normal". Wood framing can undergo a lot of shrinkage in the first few years after construction. By "a lot" I mean a few sixteenths of an inch, which is trivial for most things but can cause cracks in drywall and other surfaces.

Those diagonal cracks that extend up from the door corners are quite common. My suspicion is that they signify a slight amount of settling in the house, most likely from wood shrinking as it dries, but possibly from the foundation settling because the soil was not properly compacted before the foundation was laid. In this last case, there is nothing you can do short of jacking up the foundation, which is possible but expensive. But the good news is that with this type of settling the movement seems to occur within a few years or less, (based on my not-very-extensive experience with faulty foundations) and by ten years the settling has probably stopped as the soil has packed down.

But even more likely is that your house has experienced some shrinkage or warpage in the framing lumber. Sometimes floor joists will "take a set" or become permanently bowed downward over time. This could cause the cracks you describe. My first house had such a problem in a doorway that was over a built-up beam that had taken a set. I jacked up the beam (a fraction of an inch) with a small hydraulic bottle jack, over a period of several weeks, and the crack tightened up. I then installed a steel lally column in place of the jack.

My suggestion is to live in the house through the winter dry season and summer humid season and monitor the cracks. It's possible that they disappear in the summer, which actually is kind of troubling because it means that some structural member is flexing with changing humidity (I've seen roof trusses rise AN INCH, caused by drying during the winter heating months). If the cracks come and go from winter to summer... there is a tricky framing issue that I could not begin to solve unless I could see the entire building structure. This would not necessarily be a problem, just a cosmetic nuisance. But hey, you spent a lot of money on your house and it should look right.

If there is a humidity-swell-shrink problem, I think one possible solution lies in attaching the drywall in a manner that lets it "float" somewhat, rather than being firmly adhered to the studs. For example, drywallers routinely hang the ceiling drywall with no fasteners within a foot of the walls, so the wall drywall panels hold up the ceiling at the edges. With proper taping, the ceiling drywall is firmly connected to the wall panels more than the framing, and this lets the corner act as one unit, which discourages cracking. It turns out that well-secured drywall follows the twists and bends of the framing, ripping apart corner seams and sometimes cracking the panel as in your case.

If you notice the disappearing/re-appearing crack syndrome, it's possible that the only solution that will truly work is to replace the drywall on the offending walls, and not secure it too well around the doorways. But my approach would be (if I couldn't wait 6 months to watch the cracks change) to carve out the drywall facing and make a shallow trough in which to lay drywall joint tape. I often cut the tape to half the width so there is less drywall digging. You can use paper tape or fiberglass mesh, but the self-adhesive mesh won't stick to the gypsum, so after you carve out the valley you'll need to prime the bare gypsum core. Then you'd need to patch the joints like any other major drywall repair, and repaint the wall. But... this could crack again. 

I guess I'd also want to know if the patched-over crack has any paper or fiberglass tape. I'll bet that the previous owner just quickly spackled the cracks and slapped on a coat of paint. Standard procedure for most people. If you can patch the seams with tape and drywall compound there is a good chance that the cracks don't re-appear. But they could. It's a chance worth taking.

Also, consider applying a heavy wallpaper over the offending wall. Home Depot sells some highly embossed wallpaper that hides defects quite well.  This might be the easiest and quickest cover-up for that problem. How come I always think of the easiest solutions when I'm done writing my e-mail?


Bruce W. Maki, Editor.