I just built a detached garage in upstate NY in January/February this year. It’s 20 x 30’ with 12’ high walls on a beefed up Alaskan slab. The slab has no cracks or apparent movement. It’s got 5/8” sheet rock and had plastic over the overhead door opening while taping and painting. We ran heaters while they were taping and left them on through several days after it was painted. Within a week or 2 I noticed the first crack. Then 2 more developed about a week after that and so far 1 more about a week after the last 2. They are straight lines and obviously at a joint. The first crack is on one wall the other 3 are on the opposite wall. The taper is trying to blame the uneven heat in the garage even though he set it up. The only thing online that I found that came close to my situation indicated it might be that he didn’t use enough mud. Does that sound like the issue or is it something else? These aren’t major cracks and I’m confident it’s not a structural or settling problem. I am concerned that more cracks will develop over time. How will I know when I’ve reached the point where no more will develop? This is keeping me from setting up the garage as I don’t want to keep having them come out every time a new crack develops and have to move everything around.

Thanks,

This is the first to develop and the worst so far

 

Heat shouldn't be an issue as long as it was warm enough to finish and dry. I have a spray booth in my barn that is drywalled. It goes long periods without heat with no ill effects on the drywall. I suspect he may have thinned the joint compound too much.

 

I wonder if the cracking is due to heat or moisture changes. Sheetrock expands/contracts 0.000009" per inch per degree f of temperature change and 0.0000072" per foot for each percent change in humidity. Those are really tiny fractions but an 8' sheet will grow/shrink .026" with a 30 degree temperature change.

We used to open our house, especially in the bedroom at night sometimes letting the house get down into the 40's. It wasn't long before hairline cracks appeared. After the repairs we stopped allowing the house go through so many wide temperature swings and the problem has not returned.

 

Having a garage that was finished but installers didn't install tape (hope they enjoyed their big time savings) I had cracks like that the first year and most have not improved with age!

Being in an un-conditioned space does not help!

 

What kind of tape and compound were used? If mesh tape was used without a setting compound, these things happen more often.

 

It was paper tape. I can look at an extra bucket of compound the middle of next week when I get back there.