The developers of at least 2,000 condominium apartments in Washington will be allowed to complete the conversion or costruction of their units despite Tuesday's City Council vote to halt nearly all further conversions for 90 days. Most of the units are concentrated near downtown or west of Rock Creek Park.

In effect, this means that conversion can proceed on one of every five apartments in the city for which a conversion certificate has granted. Except for new condominium projects, the vast majority of the units are now rentals.

The projects can be completed becauyse the measure passed on Tuesday permits Mayor Marion Barry to exempt any project in which there has been substantial progress or investment leading toward conversion. In addition, the mayor can exempt those units in which tenants have agreed to buy and convert a project themselves.

The developments range from several smaller projects of four or five untis each to larger buildings with hundreds of units, according to a list or exempted projects issued by the mayor's office.

The projects include 26 conversions with 1,910 units and three new buildings with 101 units.

Developmers, landlords and tenants expressed extreme confusion yesterday as they tried to interpret the council legislation. Barry has said he willsign the legislation and issue regulations to enforce its terms.

"Nobody knows what it [the legislation] means until the regulations are issued," said Stee Guttman, an attonrey who, with several partners, has a contract to purchase and convert a building at 2800 Wisconsin Ave. NW. "We don't know where we stand."

And attorney Benny L. Kass, who represents more than 20 tenant organizations that are attempting to purchase their buildings, said many of his clients' plans are uncertain now.

"I'm confused," Kass said. "We're repesenting a group that just got a notice about a week ago about an intent to convert to condominiums I won't know for maybe 15 to 20 days whether the developer is exempt or not. What do I do?"

Robert L. Moore, D.C. housing and community development director, said yesterday he hopes to have the regulations published by June 4. He said the emergency statute poses some difficult questions.

For example, he pointed out, the statute says that projects in which there was "substantial financial investment on or before May 22, 1979, in its conversion," can be exempt.

"How do you define substantial investment?" Moore asked. He said three staff members will draft regulations and try to answer such questions over the next few days.

Several condominium developers said yesterday that the emergency moratorium does not solve the city's rental housing problem, which they contend stems from rent control.

"I've had it," attorney and developer Jeff Cohen said. "I'm getting out of the residential multifamily rental business in Washington. I'm selling what I've got. I've been involved in sales for hundreds of units over the last two months."

G.V. (Mike) Brenneman, a condominum specialist who said he has one project that may be affected by the moratorium, said, "The thing that hits us the hardest is we thought we had passed the point where we would see this type of legislation on an emergency basis, with no fact-finding and no documentation."

Following is a list of condominium projects-26 conversions involving 1,910 units and 3 new buildings with 101 units - that can be completed despite the 90-day moratorium voted by the City Council on Tuesday. The list, dated as of May 18, was provided by the mayor's office:

614 Maryland Ave. NE (5 units)

624 Maryland Ave. NE (9 units)

101-103 Second St. NE (7 units)

3225 Grace St. NW (new construction, 35 units)

1825 Florida Ave. NW (11 units)

3616 Connecticu Ave. NE (30 units)

1835 16th St. NW (5 units)

243 10th St. SE (5 units)

2009 Belmont Rd. NW (15 units)

323 Maryland Ave. NE (6 units)

4570 MacArthur Blvd. NW (34 units)

2129 Florida Ave. NW (46 units)

1731 T. St NW (5 units)

2310 Ashmead Pl. NW (34 units)

1615 Q. St. NW (168 units)

11 Second St. NE (30 units)

1316 New Hampshire Ave. NW (44 units)

Harbour House SW (425 units)

2800 Wisconsin Ave. NW (107 units)

2032 Belmont Rd. NW (157 units)

Calvet Park (new construction, 28 units)

1880 Columbia Rd. NW (36 units)

4201 Cathedral Avenue NW (620 units)

1725 New Hampshire Ave. NW (36 units)

2115 S St. NW (10 units)

925, 929, 933, 941 Randolph St. NW (16 units)

1742 U St. NW (4 units)

2501 M St. NW (new construction, 38 units)

4471, 4481, 4491 MacArthur Blvd. NW (45 units)