Waitakere comprises a class 6 shelter shed and a former Post Office. The shelter shed has a rectangular plan and a corrugated-iron skillion roof. It is timber framed and clad, with shiplap weatherboards. It has boxed corners and a centrally placed pair of sliding doors. A 1938 partition divides the space in two and there is one window on the end wall (1919). Adjoining the other end of the shelter shed is the former Post Office. It has a rectangular plan, a corrugated-iron hipped roof and overhanging eaves with moulded brackets. The building is timber framed and clad with rusticated weatherboards. The platform elevation has doors on both sides with simple hoods and two multi-light double-hung sash windows between. A partition divides the space into two rooms.
The shelter shed at Waitakerei was built late in 1879 and this section of the North Auckland Line to Helensville opened in July 1881. A postal building was added to the original shed in 1880. In 1908 a goods shed was added to the postal building, but was destroyed by fire just two years later. A replacement was built in 1910. In 1911 the postmaster decided to move operations to a store immediately behind the station and the vacated premises were converted into a ladies' waiting room the following year. Waitakerei was renamed Waitakere on 27 January 1909. In 1912 the tablet system of signalling reached Waitakere and the ladies' room was divided in two to accommodate tablet facilities. An exterior door was added and soon after an internal door was added between the tablet room and the shelter shed. By 1958 the building was falling into disrepair and in 1969 Railways called tenders for a new building. MOTAT offered to remove the existing buildings. This was done in 1972 and it now forms the nucleus of the museum's vintage railway display on MOTAT 1, the original site. The main railway activity has been relocated to MOTAT 2.