New residential construction and rehabilitation of existing townhouses have been unusually strong this year in the District.

Only a few years ago, new single-family housing starts were minimal in the District and widespread rehabilitation was confined to several areas-principally Capitol Hill, Foggy Bottom and Georgetown.

But 1977, with a more plentiful supply of mortgage money and an increasing interest in living in close-in areas, has seen a revitalization that has been unmatched in recent decades. And new residential construction is likely to set a new high mark for single dwellings and townhouses.

Although much attention has been given to the new residential construction at Beekman Place, the new town of Fort Lincoln and new duplex houses near Catholic University, there are some other interesting projects in close-in locations:

For instance, new brick townhouses are being built at the northwest corner of 16th and Irving streets NW.

Another smaller grouping at the northwest corner of 15th and Church NW was sold out some weeks ago, well in advance of completion, as the result of one small classified advertisement. The developers of the five brick townhouses, sold in the $90,000 range, are architect Reid Dunn, realtor-bank president Greeenhoot Fischer and Artifex Development Co.

Somewhat farther out, at 16th and Taylor NW., Alan Pollin, 30, is completing six one-family brick houses on a long-undeveloped tract that has been in his family since the Crestwood apartment was developed in the 1940s by his late grandfather. Robert Judson Gray was the architect for the traditional dwellings that are priced in the $135,000 range. The dwellings (on small lots) have oil heat, electric air conditioning, hardwood floors and detached two-car garages.

In the 1700 block of Q Street NW, developer Builder Barrett Linde is completing some one-bedroom townhouses in traditional architectural styling. Linde earlier did a row of fast-selling new townhouses in the 1700 block of Corcoran Street NW. Earlier, he was active on Capitol Hill.

Close-in rehabilitations include the Ontario Station project of 14 completely renovated small townhouses being done by Design & Restoration, Inc., and MK Properties. Both firms are headed by Robert G. Kicherer, who said that late September occupancy is planned. Prices are about $80,000. The site adjoins a section of Beekman Place. The Ontario Station townhouses have three skylights on the second level and about 1,250 square feet of living space.

Another intown rehabilitation with a new twist is in the 2700 block of Ontario Road, where developer Samuel P. Pardoe bought five large, deteriorating rowhouses (originally developed by the legendary Harry Wardman) and did exterior renovation that enabled the houses to be sold quickly for about $65,000 on the basis that the purchasers would redo the interiors to their taste. Pardoe said that altogether 13 houses have been redone in one block.