SHIP'S TOURS : ROOM LOCATIONS

Decks 1-5 are wholly comprised within the primary hull, which is also known as the saucer or as the upper hull.
Deck 1	Bridge. Ready room, located on the starboard side. Briefing room (a.k.a. conference lounge), located on the port side. Turbolift shaft caps. Externally there is the upper sensor platform. In the area immediately behind the main bridge is space for: two escape pods (two would not be sufficient for all the bridge personnel; the allocation of specific escape pods is not known, with any allocation being presumably for controlled evacuation as distinct from dire emergency when one would go to the nearest one) spacesuit lockers aft bridge airlock a small office space a weapons locker
Deck 2	Messhall and galley. The messhall is section 13 [#54 Macrocosm]. The galley was formerly the captain's private dining room, designated Cabin 125-Alpha. Neelix fitted it out as a galley before early on in the voyage, at an unknown time but just before [#5 Phage]. Officer's V.I.P. quarters. Laboratories and storage. Sensor gear. Escape pod access.
Deck 3	Captain's private quarters. Officer's V.I.P. quarters. Photon torpedo tracker equipment.
Deck 4	Cargo bay. (See note below.) Transporter rooms 1 and 2. Externally there are the two aft torpedo launchers so internally there are the fittings relating to them. Phaser maintenance. Sensor gear. Escape pod access. Cargo bays 1 and 2 are located on decks 7 and 8 (ST:M), with cargo bay 2 located on deck 8 section 4 [#96 Drone], although in [#27 Maneuvers] it is stated that cargo bay 2 is on deck 4 and Communicator supports the view that it is on Deck 4. The loading bay doors are situated on deck 9. In [#54 Macrocosm] it is stated that cargo bays are located on decks 4 and 10, therefore (to get round the blooper) presumably, as is likely, there are several cargo bays, with numbers 1 and 2 probably being the largest or most-often used. Communicator deals with this by referring to "upper cargo bays 1 and 2" and "lower cargo bays 1 and 2". It should also be remembered that the overall height of each cargo bay's spans more than one Deck.
Deck 5	Sickbay. Sickbay is in section 15 alpha [#88 Vis à Vis]. Medical facilities comprise: a treatment area including three biobeds and a surgical bay within which is the primary biobed complete with diagnostic instruments fitted to what is unofficially known (to television staff and viewers) as 'the clamshell'. Jefferies tube access is located beside one of the biobeds. doctor's office medical laboratory which includes a replicator and storage area; the impression is given that there is access to further medical and/or medical storage facilities and perhaps even the morgue Sensor gear. Escape pod access.
Decks 6-9 span both the primary hull and the secondary hull. The primary hull is also known as the saucer or as the upper hull. The secondary hull is also known as the engineering hull or as the lower hull.
Deck 6	Holodecks 1 and 2. One holodeck's location here is noted in [#16 Learning Curve]. Voyager has two holodecks. It seems from [The Killing Game] that they are both on the same deck and this is supported by Communicator. Having them on the same deck would make sense as far as rigging power supply etc. Armoury [#74 The Raven]. Externally there is the auxiliary deflector, therefore internally there are the structure and equipment relating to this. Primary hull: Auxiliary computer core, which spans two decks (this one and Deck 7). Primary hull: Escape pod access. Secondary hull: Deuterium (matter) processing, located toward the stern Secondary hull: Externally, toward the stern, on the 'spine' of the ship, there are consumables resupply connectors, therefore internally there are fittings and supply conduits relating to these. ST:M calls them umbilical hard connect ports. The use of umbilical is heard in [Enterprise: Dead Stop] ("umbilical cords"), and in [TNG]; the latter series aired before [Voyager] and before [Enterprise].
Deck 7	Primary hull: Auxiliary computer core, which spans two decks (this one and Deck 6). Primary hull: Upper cargo bays 1 and 2. Primary hull: Laboratories. Primary hull: Escape pod access. Primary hull: RCS (reaction control system) thrusters. Thrusters are mounted externally with concomitant internal structures. Secondary hull: Deuterium tanks. Secondary hull: Warp engine core injector access.
Deck 8	Primary hull: Deuterium processing. Primary hull: Port and starboard forward docking ports. Primary hull: ODN (optical data network) and EPS (electroplasma system) main trunks. Primary hull: Lower cargo bays 1 and 2. Secondary hull: Deuterium tanks. Secondary hull: Warp engine core. This spans the height of several Decks. Secondary hull: Aft workpod storage. Secondary hull: Science laboratories. Secondary hull: Astrometrics laboratory. Upgrade work was begun in 2374, in [#73 Revulsion], with the upgrade inaugurated later that year in [#76 and #77 Year Of Hell]. The upgrade included Borg-inspired sensors.
Deck 9	Primary hull: Cargo loading doors. Primary hull: Aerowing shuttle dock. The aerowing is also known as the captain's yacht. It was not seen in action during [Voyager]. Its shape including the outline of its keel can be seen centrally located on the underside of the primary hull. Primary hull: Laboratories. Quarters (either default duty stations and/or private quarters) possibly of security personnel as Chakotay suggests "Captain, if we relocate all security personnel to deck 7 we can shut down power on deck 9 and re-route it to propulsion.", a suggestion Tuvok replies is "inconvenient but acceptable" [#3 Parallax]. It is not known if that arrangement was amended or rescinded once Voyager's fuel shortage ease particularly after [#38 Innocence]. It is possible that the arrangement, if amended or rescinded, was re-established for grey mode in late 2374, in [#92 Demon]. It is not known from Chakotay's suggestion whether he refers to the primary or secondary hull. Secondary hull: Upper main shuttlebay. Access is via Deck 10. Secondary hull: Warp engine core. This spans the height of Decks 9 to 13.
Decks 10-15 are wholly comprised within the secondary hull. The secondary hull is also known as the engineering hull or as the lower hull.
Deck 10	Main shuttlebay [earliest mention: #54 Macrocosm]. One of the episodes refers to a shuttlebay number but at the moment I cannot recall which episode. The shuttlebay model set shows the number "05". Main computer core. This spans the height of Decks 10 and 11. Externally there are the two forward torpedo launchers so internally there are the fittings relating to them. Warp engine core. This spans the height of Decks 9 to 13. Reserve warp engine core, also known as the auxiliary warp engine core. This spans the height of Decks 10 to 14. When Janeway blames the Doctor for losing Voyager's main warp engine core, in [#170 Renaissance Man], she acts as if it is the only one. Strictly speaking she is correct, but Voyager carries the components to make another. ST:M says that only the components are carried, not a complete and ready-to-be-used one. Communicator notes the existence of a "reserve warp engine core (if equipped)" so maybe Voyager did not carry even the components. The mission was expected to last only three weeks and not even a Counsellor was posted to the ship, as noted [#6 The Cloud]. Externally there is the main navigational deflector with, internally, the associated structures and fittings. This spans the height of Decks 10, 11 and 12. The main navigational deflector is commonly abbreviated to main deflector. Primary long-range sensor package. This is located immediately behind the main navigational deflector.
Deck 11	This is known as "wing"-level, i.e. level with the warp nacelle and associated main hull structure (presumably when not raised for warp speed). "Wing"-level is not, as far as I recall, mentioned in [Voyager], but is noted in Communicator. Engineering (control room - the engineering section is large and forms the engineering hull). Deflector control is in Section 59 [#84 Prey]. Life support including artificial gravity can be shut off from this Deck. It is possible to route all bridge functions to engineering, as depicted in [#108 Bliss] and [#145 The Haunting of Deck 12]. Engineer's office. Its location is according to Communicator, but the office is not seen or referred to on television. TOSTFF also calls the main science lab "the chief engineer's office", but the main science laboratory is on Deck 8 Section 22, as noted in [#96 Drone]. Presumably therefore the science lab is a workspace area which is principally used by the chief engineer, but in order to keep in with Communicator as well, we should surmise that the chief engineer's office is on Deck 11. That would be logical since it would be close to main engineering. Communicator states that the "engineer's office" is on Deck 11 which, by dint of not mentioning the "chief engineer's office", indicates that they mean "chief engineer's office". Warp engine core. This spans the height of Decks 9 to 13. Reserve warp engine core, also known as the auxiliary warp engine core. This spans the height of Decks 10 to 14. See note under Deck 10. Main computer core. This spans the height of Decks 10 and 11. Externally there is the main navigational deflector with, internally, the associated structures and fittings. This spans the height of Decks 10, 11 and 12. The main navigational deflector is commonly abbreviated to main deflector.
Deck 12	Warp engine core. This spans the height of Decks 9 to 13. Reserve warp engine core, also known as the auxiliary warp engine core. This spans the height of Decks 10 to 14. See note under Deck 10. Antimatter tankage. Navigational control. Environmental control [#54 Macrocosm]. Externally there is the main navigational deflector with, internally, the associated structures and fittings. This spans the height of Decks 10, 11 and 12. The main navigational deflector is commonly abbreviated to main deflector. Escape pod access.
Deck 13	Warp engine core. This spans the height of Decks 9 to 13. Reserve warp engine core, also known as the auxiliary warp engine core. This spans the height of Decks 10 to 14. See note under Deck 10. Brig. There are two brigs [#77 Year of Hell, Part Two]. It is not known if they are both on the same Deck. Externally there is the aft tractor beam emitter and therefore associated internal fittings. Crew quarters. Presumably some or all quarters are for engineering staff. There may be crew whose primary assignments are not as engineers, for in [#70 The Gift] Chakotay tells Janeway: "She's [Torres is] requesting all personnel with a level 3 engineering rating or higher to lend a hand [to help dismantle the Borg implants]." and Janeway grants the request. That implies they would be pulled off other jobs and assigned to engineeering for the duration. Many crew quarters are for shared occupancy e.g. Vorik, an ensign assigned to engineering, has a bunk in his quarters [#58 Blood Fever]. Laboratories. Escape pod access. Communicator notes this Deck only as "Escape pod access 9" instead of, as with the other relevant decks, "Escape pod access". As no explanation is given for the "9" and it does not seem to make sense, I think "9" is a misprint. It is not an even number so if "9" refers to the number of escape pods accessible from this deck they would be spread non-symmetrically which is against the symmetrical design principle of Starfleet ships, unless one is located right at the front (not so) with 8 spread symmetrically on each side. ODN (optical data network) and EPS (electroplasma system) secondary trunks.
Deck 14	Antimatter processing. Externally, the primary tractor beam emitter is located at the rear of Deck 14 on the trailing edge of the Engineering hull, underneath the shuttle approach ledge. Therefore internally there are fittings relating to this facility. Reserve warp engine core, also known as the auxiliary warp engine core. This spans the height of Decks 10 to 14. See note under Deck 10. Escape pod access. Landing strut systems. These are for storing the four landing struts and feet within the hull when not in use, and for extending them during landing and subsequent take-off.
Deck 15	Antimatter loading port. Plasma relay room [#140 Good Shepherd]. This presumably is connected, by subject matter and probably therefore by geographical location too, with the antimatter loading port. The plasma relay room includes Junction 16 [#140 Good Shepherd]. It is possible that all this is what Communicator means by "plasma relay junction room". Landing struts. There are four landing struts and feet which are kept folded within the hull when not in use. They are extended for landing the ship and subsequent take-off.

Voyager has 257 rooms: "That's one room down, 256 to go," the Doctor tells Seven in [#75 Scientific Method].

Crew quarters are mainly in the upper saucer forward of the bridge module, and some are located on deck 13.

There is additional information in SHIP'S TOURS: MIX: Large 3D cutaway drawing of USS Voyager (with option to invoke detailed illustrated labels). Subjects covered include turbolift maintenance bay, more on environmental systems, the storage of deuterium etc.