The dynamic purchasing agreement is being managed by procurement specialist London Housing Consortium and is estimated to be worth £5bn over its 10-year term.
The Welsh Government has set a target of building 20,000 new affordable homes by the end of the term of this parliament.
While housing associations in Wales are planning to double current build rates to deliver at least 75,000 affordable homes in Wales over the next 20 years.
Works to be delivered are new build housing projects, including housing, bungalows, flats, apartments and accommodation such as care homes and student accommodation.
These will vary from single smaller sites to complex multi-site projects and is accommodated through a four-tiered lot structure of up to 5 units; 6-15 units; 16-49 units; 50 units and above.
The mega framework will also be split into 16 territories to support this house building programme.
The proposed lot structure for south and mid-Wales
Blaenau Gwent; Bridgend; Caerphilly County; Cardiff; Cаrmаrthеnѕhіrе; Ceredigion; Mеrthуr Tydfil; Monmouthshire; Neath Pоrt Talbot; Nеwроrt; Powys North; Powys South; Pembrokeshire; Rhondda Cуnоn Taff; Swansea; Torfaen; Vаlе оf Glаmоrgаn.
Interested firms can prequalify through the link.