Interior
Opening
The process of
installing a roof window is much like installing a wall window, with a few
added steps and obvious precautions from falling. And like most windows,
the majority of the work involves framing the opening -- two openings when
framing a shaft.
It's usually less hassle to start installation by
creating the interior opening first. This is done by marking the roof
window opening on the ceiling or unfinished framing.
If you have to
cut through into the attic, check for wiring that might be in the way and
remove any insulation in that area. Cut the opening and remove the drywall
or ceiling material.
Reinforce the outer ceiling joists with
same-sized lumber pieces screwed on each side extending to the next
header. In some cases this may be the entire ceiling length.
NOTE:
Screws are suggested here because hammering may crack existing drywall
seams.
Remove the ceiling joists that occupy
the interior opening, cutting back to accommodate the headers (
minimum double-headers = at least 3") on each side. Install the
appropriate-sized headers. If you're not sure, contact a building
inspector. But there should be at least two pieces of lumber on each
side.
Recess header the thickness of the ceiling drywall. Install trimmer
studs between the headers on each side of the opening at the proper
width.
Later, you'll need to frame between the ceiling
opening and the roof window frame in order to support the window and hang
the drywall. For that reason, we'll frame the window on the roof next
instead of finishing out the shaft.