The Engineer-in-Chief's Technical Liaison Letter, published on 1 June 1949, announced approval for the formation of a regal regiment dedicated to construction tasks.

He was tasked with organising and raising the unit from dispersed maintenance troops, marking 25 January 1950 as the official birth date of 21 Construction Squadron.

At this time, the squadron was staffed by a core of wartime sappers, mainly from the 6th Division, and New Australian civilians, who made up approximately sixty percent of the unit's personnel.

The squadron erected three Double Storey (DS) Bailey Bridges, each with a Military Load Classification (MLC) of class 30 and spans ranging from 80 to 90 feet.

Additional tasks encompassed resource extraction for construction, water purification and supply, electricity generation, surveying, bridging, rafting, and civil aid.

This program involves formal training at the Army Apprentice School combined with practical experience through works supervised by 21 Construction Squadron and civilian detachments.

The SQLG buildings were completed, and two northern projects were undertaken: the Light Horse Dive at Robinson Barracks, NT, and a scale camp at Mt.

In 1997, the squadron participated in Exercise Tandem Thrust along the Bruce Highway, with tasks including the construction of Turners Bridge, loading ramps at Camp Growl, and Samuel Hill airstrip.

The year also saw the first Tonga detachment deployed to the South Pacific island, tasked with building a new headquarters facility at Taliai Camp for the Tongan Defence Force.

Concurrently, the rest of the squadron participated in Exercise Croc 99 at SWBTA, which included constructing two bridges, roadwork, and clearing RAAF bombing sites.

The Squadron also deployed with the multinational peacekeeping force INTERFET to East Timor,[7] where it focused on road repairs during the wet season and supported other units.

As a member of this formation, the squadron remained stationed at Gallipoli Barracks, Enoggera, where it contributed to the development of buildings and infrastructure adjacent to the Regiment Headquarters.

These missions included developing health, education, and security infrastructure, such as constructing bridges at key river crossings in Uruzgan and neighbouring provinces.

Additionally, several Squadron personnel were deployed to supplement Combat Engineer Regiment sappers with their technical expertise and construction skills.

The program aims to enhance the environmental health and living conditions of Indigenous Australians and support the National Agreement on Closing the Gap.

The program has successfully delivered various projects, including housing and subdivisions, road upgrades, sewerage treatment plants, airfield construction, health clinics, telecommunications infrastructure, school improvements, and potable water supply systems.

The physical training instructors supported the Fregon Bulldogs AFL team and helped establish an exercise program at the local school.

Despite challenges such as unseasonable rain and asbestos discoveries on key sites, AACAP 2013 was a resounding success, leaving a lasting positive impact on the Fregon community.

Health initiatives were notable, with daily dental and medical care provided in Toomelah and Boggabilla, along with physiotherapy, sports injury treatment, and veterinary services for pets.

Overall, the 2017 AACAP deployment in Toomelah greatly improved community infrastructure and health services, while also providing valuable skills training and experience for the squadron members.

The squadron's key achievements encompassed the construction of a community gathering space, an ablutions block, and two large culverts to enhance access and mitigate the effects of the wet season on creek crossings.

Additionally, the squadron delivered accredited and non-accredited training in construction, guiding, and healthy lifestyles and supported local sports, including the Jigalong Eagles AFL team.

The squadron's primary construction tasks included building a 20x12 metre Men's Shed for community projects and social gatherings, and developing two 5-lot housing subdivisions to support future growth.

The deployment also involved delivering health services, training in various trades, and providing professional development, which significantly enhanced the community's infrastructure and wellbeing.

Instances of support include flood relief in Wentworth and Euston (August 1956), assistance during the Viscount crash at Mangalore (October 1964), and aid for the Yea bushfire emergency (1966).

In Grantham, which had been severely impacted by an inland tsunami, the squadron's Plant/Transport Troop cleared debris, removed destroyed houses and handled large machinery.

Concurrent with ongoing support to Northern New South Wales in 2022, the squadron began deploying elements to Lekutu, Fiji, for Construction Engineering Team Phase 2, where they further completed the reconstruction of two school buildings damaged by Cyclone Yasa.

[18] From March to April 2022, 21 Construction Squadron, supported by elements from 6 ESR, deployed to Lismore, NSW, as part of the Whole of Government Response to the February floods.

While deployed, the squadron, in collaboration with the Vanuatu Mobile Force, restored 17 school classrooms and 5 medical facilities, distributed aid, and cleared debris from public roads and spaces.

Its responsibilities encompass several key areas: reconnaissance and planning, which involves assessing the site and determining project requirements; project development and design, focusing on creating detailed plans and blueprints for construction; contracting and procurement, where it manages the selection and acquisition of necessary resources and services; and quality control (Level 3 QC), ensuring that all construction work meets established standards and specifications.