Dear Mason:

I live in a 1960's home in the Richmond, VA area.  I seems to be of good quality construction, but I have had problems with the crown molding pulling away from the ceiling, which leaves an ugly crack.  We have tried caulking it, but it re-appears after a year or less.  Is there something wrong with my crown molding?  What can we do to fix it forever?

Lisa B

Lisa:

Ahhh, cursed crown.  It's ALIIIIIVE!

Indeed, in all likelihood, that is the problem.  Most crown molding is made of living (or once-alive) material - wood.  All wood has a tendency to expand and contract with swings in temperature and moisture conditions.  This is particularly severe "across the grain" - in the case of crown, that means from top to bottom.  When it contracts (during dry conditions), it's pulling away!

Even with 40-year-old wood, this is still inevitable.  The solution is to mderate those swings in temperature and humidity - typically via running your heating and air conditioning at a consistent temperature (this also controls humidity to some degree, depending on type of your HVAC systems).  Drastic setbacks during "away" periods might be good for the earth and your heat bill, but might play havoc on your millwork.  Likewise, while opening windows on a "nice" day is great, it may affect your home humidity levels.

I'm sorry that I can't report an easy solution... even if one were to re-nail and glue this millwork every-which-way-from Sunday - if this wood wants to move, it will move!

There are some materials that may be substituted for less movement - tighter-grained millwork (this is rare today, unless custom milled and also quite costly), MDF moldings (which are essentially engineered materials made of wood fiber), PVC on so forth.  If the problem is so awful that you are compelled to replace the trimwork, that would do the trick.

Otherwise, keep your home tight, the indoor weather right, and keep that caulk gun handy!

Mason

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