DIYbanter - Need help repairing exterior door

Hey all,

My (century-old) house has a detached garage. The door by which I (and
not my vehicle) enters and leaves the garage needs help, and I don't
know what I'm doing, so I figured I'd ask you all to share your
experiences.

The bottom end of the hinge stile has rotted out (the rot stops below
the bottom hinge, so structurally, I think the door is OK), and the
bottom rail fell off last week. So I can tell that the door was
cope-and-stick, and the bottom rail was held in by 4 1/2" dowels in
each end. I need to repair or replace before the winter gets here.
South-west ohio, so I'm looking forward to about a foor of snow falling
(and then melting) over the next four months. Oh, and the door is
going to be painted white.

All of the interior doors in the house have a five-panel design, two
long parallel vertical panels at the top, a horizontal panel across the
door at the height of the door knob, and two shorter vertical panels
below that. On the door to the garage, the two upper panels are
replaced by a single window. So the door has four rails, one at the
bottom, one below the middle panel, one between the middle panel and
the window, and one at the top. The door measures a shade under 84"
tall, 32" wide, and 1 3/8th inch thick. At the blue BORG, I found a
similar door in the catablog that they would be willing to
special-order, for around $400. No money left for that kind of outlay
right now.

The damaged area of the stile is on the inside edge (toward panel and
rails, opposite hinges), and up from the bottom. The damage goes no
higher than the bottom nine inches. But the glue joint between the
middle two rails and the hinge stile have failed. The glue joint to
the top rail looks intact.

In a fit of enthusiasm, I bought a Bondo Rotted Wood Repair Kit that
looks like it has enough material to replace the wood that is totally
missing. I also have stockes of Titebond III and slow-set epoxy.

I've taken a wire brush to the damaged area, and some came off. Along
the joint to the rail, on the inside side of the door, about half the
thickness of the stile is gone And what is left is pretty spongy.
Again, it's the bottom 9 inches. The stile is 5 1/4" wide (and just
under 84" long). The damage is about 4" wide, 9" tall, and the whole
thickness of the piece. Inside edge, where it joins the bottom rail.

I could leave all the spongy bits, and use 6 coats of the wood
stabilizer that came in the bondo kit, as per the instructions. Then
fill in the rotted area with the filler, and set the filler around new
dowels I insert into the rail. I wonder about how strong the bondo
will be? That joint will be in compression, as the weight of the door
is pivoting into the hinge stile.

My second choice is to be more agressive with cutting out the soft
bits. Then the Bondo filler is the whole thickness of the door, 1 3/8
inches.

My third choice is to totally cut off the bottom of the stile, and to
mill a solid replacement piece. How would I join the new piece to the
old piece? Biscuits? Dowels? Scarf? I have a scrap of pressure
treated wood big enough. Will pressure treated wood glue normally?
I'm leery of milling it down in my basement workshop, as I have a
vacuum cleaner sucking through a separator lid on a garbage can for
dust collection, and no air filter. The router table could come up the
stairs and outside, though. I've never tried to mill such a
complicated profile with the router; I'd need (elliptical? must
measure precisely) cove and round-over bits. I have a straight bit,
and my ogee might work to complete the profile.

Anyway, thanks for any input. I'll check in over the next few days,
and summarize any responses sent in email.

Chris