You build the rooms with "Room Blocks" - a column of 4 squares. You roll 1d6 to determine how many "room-blocks" you'll use to build the room. You have to place your room-blocks in-line with your current room. If you run out of room for the number of room-blocks you rolled, use the left-overs to build the next room up the grid.
I rolled 3 for room one. I rolled 5 for room 2. I rolled 1 for room three. I rolled 6 for room four. I rolled 2 for room 5. I rolled 2 again for room six but there wasn't enough space for a 2-block room. I made room 7 with the left-over block. Skipping ahead to room 12, I rolled 3. Again, not enough room for 3 blocks. Room 12 uses 2 of the 3 blocks I rolled. Room 13 is formed with the left-over block.
East/West door will always exist within the boundaries of the mapping-grid. Sometimes, there may be a north door. This is determined by rolls for "room features". There is always a north door where there is a gap in the black lines.
