After three years of planning and months of delicate dickering, Washington-area building trade unions are on the verge of completing a pact with contractors in which they have agreed to give up many of their traditional work practices and keep their same salaries and benefits for another year.

The unusual alliance of labor and management is the result of pressure to head off the growing competition from lower-priced nonunion workers by cutting costs and increasing productivity.

The "multicraft agreement," under which trade unions have agreed not to strike, already has been signed by 22 of the 27 union locals and nearly all contractor associations in the Washington area, according to spokesmen for both groups.

The agreement's proponents are now reportedly in a "war of nerves" with the hold-outs, hoping they can be brought into the fold before their contracts expire.

The agreement, which will be in effect for at least the next year, could pit worker against worker if the holdouts decide to strike, because those who have signed do not intend to honor those picket lines, union leaders say.

"The sacrifices being made by those who have signed are like cutting your arm off," said John Quackenbush, secretary-treasurer of the Washington Building Trades Council, which coordinates the activities of unions locally. "With your only remaining arm, you are not going to carry those who simply are greedy for 'more.'"

With no more giant construction projects, such as the subway, in the immediate offing, he said, "Where I see employment for our workers now is the jobs we're going to take away from nonunion. We can never beat'em money-wise (on wage-rates), but we're trying to give the contractor a competitively priced building to deliver, quicker, with better quality."

Construction workers in the Washington area are paid about $10 an hour.

Quackenbush said the agreement covers about 22,000 workers on jobs in the District and its suburbs, 19 counties in Virginia and five counties in Maryland. It is not known how many nonunion construction workers there are in the Washington area.

In addition to the no-strike and wage-freeze provisions, the agreement also seeks to bring uniformity to starting times, holidays, lunch hours, payment rules, contract expiration dates and other work patterns which have in the past varied among the numerous crafts at work on the same job, often resulting in chaos and extra expense.

The "most controversial" provision, according to Quackenbush, is one that makes workmen's compensation payadle on the basis of where the construction is being done. Under the old system, he said, workers were paid the District rate - the highest in the country - no matter where the job was located. "This was a tremendously costly item for the contractor and it has cost us jobs."

The agreement already has had some impact according to Frank Williams, president of the Washington Construction Employers Association, which is an ad hoc group composed of the employer associations, such as the electrical contractors, which bargain with the various crafts.

"I'd say up until a few months ago, the trend was totally downhill," Williams said, referring to the muchrooming loss of jobs to nonunion contractors. "All we can say at this point is we've leveled that off, so that we're not losing any more."

Such agreements are a growing trend around the country, according to Joe Maloney of the AFL-CIO construction trades department, although he said he is not familiar with the Washington agreement's provisions.

"This is one way to strengthen the construction trades - to offer employers eight hours work for eight hours pay," he said, acknowledging the competitive pressure from nonunion labor.

He said last week was the official start of a new nationwide campaign to organize the construction industry, starting in Los Angeles, "to accept the challenge laid before us."

A spokesman for the nonunion building industry, Bob Ramsey, said of the multicraft agreement, "we are please to see that the organized sector is finally realizing a method our people have been using for years."

Ramsey is executive director of the Washington area chapter of Associated Builders and Contractors (ABC), which represents some 300 nonunion or "merit shop" contractors. (Merit shop means using union as well as nonunion labor based on low bids.)

ABC figures show the nonunion labor force working on high-rise residential construction in the District rose from 46 per cent in 1973 to 79 per cent in 1976. This shift was part of a national trend, with more than 50 per cent of national industrial-commercial building being done by merit shop labor, according to the ABC.

The multicraft agreement's provision on workemen's compensation could save a contractor from 25 cents per man-hour on low-hazard jobs to $1 per man-hour on hazardous work, such as steel erection, according to Williams.

Quackenbush termed the provision "more controversial than the money in the envelope," because it protects men who get hurt in accidents. Some unions are planning to compensate for the change by using some of their health and welfare funds to buy extra insurance to cover serious injuries, Quackenbush said.

A provision allowing the contractor more flexibility in shift work around the clock - without charging premium pay for it - will allow him to "knock a 12- or 13-week job down to maybe six weeks, by working nights," Quackenbush said.

"Somebody observed the other day that with night work, at places like shopping centers, you can save money just be eliminating the girl-watching time."

The agreement also cuts out "showup" pay for weather of acts of God. In the past, this provision has ontitled workers to some pay even though their work was rained out, for example, as long as they showed up that day. It also calls for improved hiring qualification standards, Quackenbush said.

Under the agreement, Quackenbush said, "if a man hasn't graduated from a training program, or is not a journeyman, he gets sent to take a test given by the local. We've had some people who were good at getting jobs, but not at working. Then we have to represent them in grievances sometimes when in fact they shouldn't have been hired. They could have been a relative of somebody. You know, the contractor's brother-in-law, or something."

Among those who have not yet signed the agreement are the operating engineers, one structural iron workers local, a steam-fitters local, a bricklayers local and the painters, according to Quackenbush and Williams.

Spokesmen for some of the holdouts declined comment or could not be reached.

Eva Poling, executive vice-president of the Mechanical Contractors Associaltion, which has not signed, said that her organization is still trying to get clarification on certain areas of the agreement. "We have a diverse membership, we are governed by by-laws, and we are a democratic organization."