The Building Workers' Trade Union (BWTU) was a trade union in Ireland.
From 1959, it was affiliated to the new Irish Congress of Trade Unions.
Membership peaked at 2,096 in 1950, but then fell as many of the affiliates left, until only the Brick Layers remained.
In 1981, the union adopted the name of its sole affiliate, the Ancient Guild of Incorporated Brick Layers' Trade Union.
[1] In 1998, it merged with the National Union of Wood Workers and Wood Cutting Machinists, to form the Building and Allied Trades' Union.