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lkstaack 02-12-2012 02:46 PM

Drywall Crack Diagnosis
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I purchased my 20 year old house 6 months ago and it is time to repair and paint the living room. I request advice from expert DIYers on diagnosing the cause of drywall cracks. The drywall cracks pictured may be a result of water damage. The attached photo shows the transition from wall to ceiling; the ceiling seems lighter in color but they are in fact the same color.

The photo shows discoloration near the vertical and horizontal wall edges as well as drywall cracks 1) on the bull nose corner; 2) on the ceiling kind of parallel to the wall; and 3) on the ceiling parallel to the corner bead transitioning two different ceiling angles. The discoloration may be caused by a poor touch-up paint job or water damage. I donít know what would cause cracking at the tip of the bull nose corner bead (1); water damage? The ceiling crack (2) seems to be a stress crack? Again, maybe water damage? The crack (3) may be the corner bead edge lifting? The photo doesnít show it, but this crack continues along most of the 10í long joint. Now, does anyone have any ideas what could be causing these cracks?

The roof above the suspected water damage had issues; the flashing within a valley was clogged with debris because the cement tiles were too close together, so they were trimmed. This may or may not have caused a roof leak during one of Southern Californiaís rare cloudbursts. However, there is no other indictors of water damage except for the cracks and discoloration. There is no attic access.

I guess the first thing I must do is determine if the drywall sustained water damage. Would I do this by checking the firmness of the drywall by sticking an awl into it? I donít want to start ripping up drywall, do I?

If crack (2) is a stress crack, I can just repair it by cutting out the crack, taping it and filling it, right? Should I remove all material around the edge of the (3) corner bead and fasten down the beadís edge better?

Anyway, any assistance on one or all of these issues would be appreciated. Thanks.

sixeightten 02-12-2012 02:51 PM

That looks like a crack from the house settling. Pretty good shape for 20 years old. There does seem to be a little discoloration there as well. You could definitely poke around a bit since you need to take care of the crack anyway. I bet the leak was very small and the crack allowed it to seep in a bit. Probably easily repaired.

boman47k 02-12-2012 07:21 PM

What is the width of that wall? Any chance it has a narrow strip for the last piece of drywall?

I just noticed crack #2 is about the same distance from the wall. I also noticed the water stains a little more clearly.

Water prob affected the mud in the corners making it crack. The distance looks about right to me.

lkstaack 03-09-2012 12:16 PM

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I request advice: should the newly exposed edging be tacked down prior to re-taping and plastering? How do I do it? As you can see, there isn't any holes to put a screw through.

I removed the plaster from around the crack. I found:

1. It had been repaired before. The repair which consisted of mesh tape and joint compound was separating from the original plaster.

2. The original drywall was not flush with the original bullnose edging.

3. The original edging was not mounted with nails/screws. Was it pushed into joint compound? The ceiling edging doesn't use nails either.

4. The original drywall tape did not cover the gap between the edging and drywall, it was tucked under the edging. Why?

5. Alot of joint compound was used to fill the large crevice between the drywall and bullnose edging.

In order to repair this, I assume that I must 1)ensure the edging doesn't move, and 2) use drywall tape between the edging and drywall. I'm not certain of the correct way to keep bullnose and ceiling edging from moving and if joint compound is good for filling a crevice about 3/16" thick. I could sure use some advice.

EDIT: I found nails holding down one side of the bullnose edging and nails on both sides of the ceiling edging. However, I still haven't found evidence that drywall tape was used between the drywall and edging.

lkstaack 03-10-2012 10:17 AM

I have removed the joint compound around all of the cracks, screwed down flexing corner beads (I made holes in the metal where if there were none at flexing areas), and applied mesh tape and new joint compound. Although I now know that drywall tape is not usually used between drywall and edging, I hypothesize that much of the cracking was due to the thickness of the joint compound around these joints (1/4" thick at some locations).

I hope that the use of tape will strengthen the thick application of joint compound and prevent future cracks, because I don't want to have to do this again.

chrisBC 03-11-2012 04:20 AM

If you are using mesh tape and use regular ready-mix joint compound, you are running the risk of cracks down the road. Mesh tape should always be coated (first coat anyways) with a setting type compound (powdered that is mixed)...

Just FYI

lkstaack 03-11-2012 08:54 AM


Originally Posted by chrisBC (Post 875149)
If you are using mesh tape and use regular ready-mix joint compound, you are running the risk of cracks down the road. Mesh tape should always be coated (first coat anyways) with a setting type compound (powdered that is mixed)...

Just FYI

Thank you for your advice; this is the first time I've patched this much drywall, so any word of experience is helpful. As it happens, I am using Westpac Fast Set 40 setting type compound. It's supposed to set in 40 minutes, but some of my patches are so deep it's taking several hours.

framer52 03-11-2012 09:45 AM

Just becasue it says 40 minutes, doesn't mean it sets in 40.

For repairs and small jobs I always use 20 minute mud. Mix small amounts and keep putting it up until you are done.

The 40 min. will help make this a permanent repair.:thumbsup:

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