Hi, new to group so first post.

I bought my first home last year. It is a small two bedroom, two bath
on a lot and 1/2 with a detached two car garage with an upstairs
rental unit.

The house is about 1000 sq. ft. The living room is awkward for
furniture, one bedroom is used for an office, and the other is used as
master.

Off the kitchen there is a small room (about 8 x 8) that used to be
either a mud room, a porch or a laundry room and the roof is gabled.
It is enclosed and someone built a framed in space for the water
heater (about 3 x 3). There's access from the kitchen to this space
that leads to a door to the back patio and a door to the master bath.

The master bath was added next to the old mud room with two doors, the
other being from the master bedroom. This door exits what I assume to
be through the former siding of the house into this addition. The
ceiling incurred some water damage after we bought the house and I had
removed some of the ceiling drywall to ascertain the leak. The roof
is flat pitched and meets the joists for the main house ceiling.

I would like to strip the master bathroom and start all over. The sub-
floor under the cheap shower had rotted and he space is poorly used.
I'd like to take the small door from the bedroom and make it into
double French doors to a bathroom oasis and also add French doors to
the outside back patio (that I might want to make into a room
addition).

Some of the problems:

The mud room is concrete floor at a different level than the main
house and the master bathroom. I've considered removing the 3x3 water-
heater room and replacing the water heater with an "on demand" water
heater. I've also considered framing in the door and making this into
a Wash/Dryer area with storage. (Current washer/dryer is in garage
about 35 feet from house.

Master Bathroom is poorly arranged, has paneling on the former siding,
and needs to be stripped completely down to the studs.

I have a lot of time on my hands, plenty of carpentry, electrical,
plumbing skills and tools that I could do all this work. My goal has
been to design the bathroom first and then tear the old one out and
begin building.

Does anyone have any advice or suggestions? I know for certain that if
I didn't want to redo the bathroom, the sub floor MUST be replaced
because the tile put in by the person who "flipped" this house is
already cracking because of the water damage from the cheap shower. I
want to frame a tile shower, add a tub, re-arrange the toilet, add
ventilation, minimize the unnecessary linen closet and make this a
very pleasant part of the master suite. I fear that if I do all
this, the master bedroom may appear a joke by size comparison as the
master bathroom would be almost 1/2 the size of the bedroom itself.