Hi everyone. I am putting a prehund door into the rough opening. I want to
make sure my door is not twisted in the rough opening. When I say twisted,
I mean that one door jamb doesn't stick out further than the other. Is
there a special tool to check for this. I will draw a picture below, using
J for the door jambs and l for the level. However I don't think this is how
to check this. Any help is greatly appreciated. Thanks.
My understanding is that ideally each edge of the jamb should line up
with the finish surface of the adjoining wall. This is so that the
backsides of the door trim will all be in a plane, the plane of the
wall. To line up the edge of the jamb with the finish wall surface,
put a straightedge on the wall perpendicular to the jamb, overhanging
the rough opening just enough so that the jamb can be brought up
against the level.
Often the jamb thickness will not exactly match the finish wall
thickness. If it is less, pick one side to line the jamb up with, and
install an extension jamb to line up the other side. This is just a
piece of 1x material cut to the necessary thickness, usually installed
with a small reveal, just as door trim is installed with a reveal. If
the jamb is wider than the wall, then it is best to cut it down or
procure a different jamb.
Not sure what the best strategy is when the wall is not plumb, since
the door jamb should be installed plumb, which implies the edge of the
jamb can't be aligned with the finish wall for the whole length of the
jamb. Perhaps taper the jamb or use a tapered extension jamb?
Hope this helps and answers your question, I'm not sure if I
understood it exactly.
Ideally a plumb wall is great, but lets face it.... Older homes
sometimes fall out of being plumb... Not a huge issues if its
a little out. Its usually more important that its flush with the wall
as much as possible. The interesting this is when wood bends over
time. Now the wall was slight bends to it.
When I replace doors and this problem occurs I generally shave
down the high spot on the wall with a palm sander. Generally
what I am talking about is sanding the sheetrock right by
the jam. When I put the molding around the door it hides the
sanded part and the molding is flush. You'll never ever see
a bow in the wall.
If you want to make sure that the surface of the jamb sides and
head are all in a single plane, the easiest way is to put a proud
finish nail in the four corners. Tie off a dry line to create the
diagonals of the jamb (make an x going from top right to bottom
left and top left to bottom right. When the strings touch at the
center where they cross, the jamb is in plane.
For those who do not know, simply nailing off the jamb to run with
the drywall on each side of the opening may not give you a jamb
that is in plane. If it is not, the door will gap at the top or
bottom of the strike side jamb. The condition can often be
disguised with creative installation of door stop often resulting
in a door that needs to be pushed a little hard to latch as you
warp the door into location.
You probably won't see many carpenters do it this way, but you may
see them shim and tack a jamb, hang the door, and modify the plane
of the jamb with a heavy hammer to accomplish the same thing that
the strings tell only using the door itself to determine plane.
(top posted for your convenience)
Keep the whole world singing . . . .
DanG (remove the sevens)
I see a several posts trying to re-invent the wheel. The answer, since
it is a pre-hung door, is to tack the hinge jamb, shut the door and
when it is tight to the stops on all three sides the door is in plane.
Tack the other two sides after adjusting them so the gap between door
and jamb is the same all the way around. Simple. The problem comes
when the wall is not plumb. You may not be able to have the jambs in
plane if the wall is far enough out of plumb. There are tricks to fix
that (planeing the jamb, planeing the wall, installing off plumb and
moving stops etc.).
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