If you place a tile that creates a junction where 4 tiles connect to
create an open field. . .
. . .You may place your barn directly on that junction instead of
placing a meeple. In other words, the corner of each tile forming
this junction must only depict a field in order for a barn to be
placed there.
You may place your barn on an unoccupied field or a field already
occupied by farmers, even if you are not one of the
farmers. You may not, however, place your barn on a field
already occupied by another barn. You can however join barn
fields by placing your barn on an adjacent field, then place
an appropriate tile that will join multiple barn fields together. Once
placed, your barn remains in play until the end of the game.
FARMER SCORING AFTER BARN PLACEMENT
If there are farmers in the field where you place your barn, that
field is scored immediately just as it would be at the end of the game.
Therefore, the player with the most farmers in that field scores
3 points per completed city in the field. It does not matter which
player placed the barn that initiated this scoring.
Red places a barn.
Blue scores 6 points for
the 2 completed cities in the same field and returns their farmer
to their supply.
Then, all farmers occupying that field are returned to their
respective supplies.
FARMER SCORING BY FIELD CONNECTION
A field occupied by a barn may NOT be occupied by farmers. If you
place a tile that connects a field occupied by one or more farmers
to a field occupied by a barn, the connected field is scored during
the scoring phase of that turn (after 2.
Placing a meeple). The player with the most farmers in that
field scores only 1 point per completed city.
The tile placed this turn connects both meeples to the barn's field.
Red and
Blue each score 2 points for
the 2 completed cities in that field and return their farmers to their
supplies.
Then, all farmers occupying that field are returned to their
respective supplies.
NOTE: If the fields you are scoring also contain a pig, after
barn placement scores 4 points and field connections score 2 points!
BARN SCORING AT GAME END
At the end of the game, you score 4 points per completed city, 5 points
per castle, in the field your barn occupies. If multiple barns occupy
the same field, all concerned players score full points.
I made the following post on carcassonnecentral:
I have a question about scoring fields that are joined to a barn field.
This is an image of just one small section of a larger map. The
barn-field on the left currently touches 6 completed cities. The open
field on the top right has 1 blue farmer and 1 red farmer and touches 4
completed cities (2 are the same as the barn cities). The open field on
the bottom right has 1 red farmer and 1 red pig and touched 5 completed
cities (1 is the same as a barn city).
OK, if any player draws a 4 field sided Monastery and decides to place
it in the open space, it will join all 3 farms! As I understand the
rules: the combined fields will now touch (6 + 4 – 2 + 5 – 1 = 12)
completed cities. The new combined field will be occupied by 1 blue
farmer and 2 red farmers with 1 red pig. Blue will score zero points.
Red will score 24 points, 2 times 12 because of the pig, and the blue
and red meeples and pig will be returned to their stacks. Pink still
own the barn-field which now touches 12 completed cities. The answer
was that this post is 100% correct!