At one time, dormers were added to attics
to let in a little light. These dormers were rarely
wider than four feet, and such small
cutouts rarely broke up the integrity of a roof.
But over the years, dormers became an element
of style and grew. And grew.
Now it is common for a dustpan dormer
to be nearly as wide as the roof, with lots of
nice windows and no collar ties so that the
owners can make better use of the space. Big
dormers are wonderful for transforming a
small Cape into a moderate-sized house.
But when the snow comes, they often are
structural disasters.
The rafters over a dormer are at