Ten more D.C. neighborhoods soared past the $100,000 median home sales price mark in 1978 and six neighborhoods experienced median sales gains of 30 percent or higher, according to new data compiled by the city's assessment office.

Twenty-eight of the 53 residential neighborhoods in the District now have median housing sales prices in the six-figure range, versus only 10 in 1976. Using average 1978 sales prices rather than median (mid-point) data, five D.C. neighborhoods had sales figures at or above $200,000, and one was above $350,000 (Massachusetts Avenue Heights).

Residential assessor George B. Altoft, who compiled the figures from recordations of single-family property transfers (excluding condominium units), termed the dollar gains in Capitol Hill (up 37.1 percent), North Cleveldand Park (up 33 percent) and Spring Valley (up 32 percent) "enough to make your head spin."

On Capitol Hill, for example, the median sales price during 1978 was $122,000, up from $89,000 a year ago and $68,000 in 1975. The fourth quarter average for Capitol Hill was over $126,000.

North Cleveland Park went from $93,000 to $124,000 in a year, while Spring Valley went from $156,000 to $205,000.

Newcomers to the $100,000 median club were Burleith ($107,000, up from $86,000 the year before), Foxhall ($125,000 versus $96,500 in 1977); Glover Park ($111,000, up from $94,000); Palisades ($111,000, up form $84,500); American University Park ($110,000, up from $94,500); Chevy Chase ($122,000 versus $95,000); North Cleveland Park ($124,000 versus $93,000 in 1977); Shepherd Park ($100,000 versus $83,000), Capitol Hill ($122,000, up from $89,000), and New Southwest ($117,000, up from $89,500).

The most expensive neighborhoods in the city by median sales price -- all in Northwest -- are Massachusetts Avenue Heights ($290,000 was its midpoint last year), Spring Valley ($205,000), Woodley ($190,000), Wesley Heights ($189,000), and Georgetown ($175,000). Georgetown's average sale price for the year was $200,000, and its fourth quarter average was close to $220,000.

The least expensive neighborhoods in Washington to buy a single home today are Barry Farms in Southeast, where the 1978 median price was $30,000 (up from $27,000 the year before), Marshall Heights ($32,000), Lily Ponds in Northeast ($35,000), and Trinidad ($36,950).

Median sales value increases for 1978 have not been computed yet but many neighborhoods registered gains well above 20 percent. Unlike past years when the most spectacular rises in value were produced in highly speculative, lower-price areas undergoing rapid reinvestment, 1978's big gains came in some of the old-line, traditional neighborhoods. Forest Hills, for example, where the median price was $172,100 last year, registered a 29.4 percent increase. Neighboring Chevy Chase showed a 28.4 percent rise; Foxhall went up by 29.5 percent and Brentwood in Northeast rose by 27 percent.

Mount Pleasant continued its recent pattern of large gains (median price increased by 27 percent last year, to $79,000, from $62,000 the year before), but other reinvestment areas rose more slowly. The central downtown neighborhood which contains Logan Circle and adjacent streets produced only a 5.3 percent median jump in 1978, to $118,500. This may reflect a market catch-up phase, however, following that neighborhood's huge 1977-78 rise, when prices went from $73,625 to $112,500.

The slowest-gaining neighborhood in median sales terms last year was Wakefield in Northwest (which registered a $1,000 loss, statistically a 0 percent change.) Again, such a static condition in a booming city may reflect the prior year's sudden jump from $77,450 to $115,500. Berkley in Northwest was next slowest gainer (4.7 percent), following by Brookland (5 percent.)

Georgetown turned in what assessor Altoft called "a typical off-year performance" for that neighborhood -- rising 12 percent in median sales price. Altoft says that since 1970 Georgetown has exhibited a pattern of big-gain and small-gain alternating years -- irrespective of the local or national economy -- that averages out at a constant 18 to 20 percent gain per year.

Since the percentage changes can be influenced by statistical quirks -- an unusually small number of houses sold in a given year, for example, or the sale of several extremely high cost properties -- multiple-year patterns are more instructive to buyers or investors than one year changes. Also, the neighborhood medians suggest only areawide trends, involving dozens or hundreds of transactions in a 12 month period, but may not be accurate valuation guides for a specific dwelling unit.

A poorly located, poorly maintained house on Capitol Hill -- where over 250 units changed hands in 1978 -- may have declined in market value, despite the surge in values of better-situated, better-maintained homes around it. By the same token, an exceptionally well rehabilitated house on the Hill may have gained 50 percent in market value in the course of 1978, far above the median.

Kenneth R. Harney is editor of the Housing and Development Reporter published weekly by BNA, Inc.