How about another "can you guess this image" contest? Probably not fair, since it was late at night, and my Photoshop efforts were a bit hurried. I'll give the hint that it's related to the remodeling...
kdb wins again! Fortunately, it's a really small crack, photographed with a macro lens, and then blown up even more. I used the Photoshop Texture >> Craquelure filter (just on the crack on this second try). Seemed like a good fit of a tool to use... :-)