Truss uplift causes cracks between the wall and the ceiling that open and close every year and you cannot plaster or caulk them shut. For details on the cause and solutions to this problem follow this link.
If you cannot do the major work required to prevent this crack from opening, or you just want to live with it without having to see it, here are some tips for hiding it.
Antique furniture making was made with sold pieces of wood, often meeting at right angles. When a glued up panel met a frame piece placed in the opposite direction, they would just tear the joint apart if you tried to glue them. So door panels were often set to float in recesses cut into the door frame – and furniture had very decorative trim pieces all around the top. Both served the primary purpose of hiding a moving crack – with the trim only attached to one piece and not the other.
So when the ceiling insists on lifting up off of the wall every winter and you cannot stop it, you can hide it.
TRIM TO THE CEILING
The traditional technique for doing this was well illustrated by my friends at CarsonDunlop – Toronto consulting engineers who train home inspectors. They show putting a trim piece attached only to the ceiling which allows it to float up and down on the wall. This works very well – especially if you have everything painted white or off-white. But as soon as you get into any strong colours, the part of the wall which gets sunlight fades compared to the part of the wall hidden behind the trim. So when the trim rises up, you see a colour change on the wall – almost like your crack was showing up again.
TRIM TO THE WALL
For walls where colour fading is a problem I would rather nail the trim to the wall itself and not to the ceiling. In fact drop it down a good half an inch and leave an “accent” space on the top. Now if the crack moves a bit you won’t see the change in that “accent” space and you won’t see the crack either. As for colour change on the ceiling, it will be all dark behind the trim so you won’t notice that either.
My preferred solution is to install a fairly large cove moulding that is attached to the wall but dropped down from the ceiling far enough to be able to slide a LED rope light into the empty space behind the cove. Of course you will have to work on how to get the wires to it discretely, but with modern LED rope lights you can not only have a dimmer action but even a dialed colour selection from the switch. Now you can have a light glow on the ceiling for great mood lighting, or indirect ceiling lighting for watching television and you can change the colour to suit the occasion. And incidentally, you never see the crack you set out to hide. So what started as an ugly crack, justifies a great decoration.
USING PLANTS TO HIDE THE CRACK
Back in 2001 I had a question that came in from Bob in Welland, Ontario where his truss uplift was causing a crack only on a corner – not far along the wall ceiling joint. His crack was right on the face of the wall on an inside corner, so cove molding was not the answer.
So I dropped by the House & Home offices in Toronto to talk to the designers for ideas as to how to hide this crack that we cannot stop. They came up with the great idea of building a column at the corner of the wall, putting a shelf on top and arranging flowers on it, spreading out enough to cover the crack. One easy way to make that column would be to cut one quarter out of a large sono tube, and paint or texture the tube after attaching it to the corner of the wall.
Camouflage is the technique for simply living with a moving crack. During the next renovation you can change the way you attach the drywall – but nothing is going to stop the truss from moving up and down.