The form, to be called the major projects agreement, is intended for use by firms on projects worth more than £50m.
The advantage for employers is that they will no longer have to negotiate separate employment agreements on individual sites. For their part, workers will have improved pay and conditions.
A spokesperson from the AEEU said the details of the agreement were yet to be finalised, but that they should be completed by the end of 2001.
Ken Jackson, the general secretary of the AEEU, said the agreement would improve the efficiency and profitability of M&E contractors.
He added that better employment relations would help to allay the concerns of key clients, many of which were unhappy with the productivity of the M&E sector.
Contractors will have a problem signing up to an agreement covering complex issues
Jackson said: "A lack of response in giving clients an all-embracing M&E package of work from design to commissioning is frequently voiced."
The proposal was questioned by some leading specialist contractors who were concerned at the diversity of issues covered by the agreement.
A senior executive at one leading M&E firm said: "Problems will occur in defining large sites, and leading contractors will have a problem with signing up to a large agreement covering complex issues."
Projects set to be included in the agreement are Heathrow Terminal 5 and the London Underground's public–private partnership.