Barratt Developments sold its homes for 6% more during the first half as the number of houses sold made up a bigger share of the total, although volume growth for the year will be "limited".Britain's largest housebuilder said the average selling price (ASP) rose to £176,000 in the six months to 31 December. Private ASP was up 11% to £192,000 and social ASP grew 4% to £124,000. Underlying selling prices remained stable.More expensive houses represented 65% of the 4,832 completions in the half-year, up from 60% in 2009. Completions were down over 4% during the period as a 74% surge in social housing to 1,127 failed to offset a 16% drop in private completions to 3,669. Interim revenue is about £875m, Barratt said Wednesday, up a touch from £872.4m a year ago. Forward sales are also in line with 2009 at £645.7m.Operating margin for the period is put at around 5%, up from 2.4% the year before. Barratt identifies "unusually low levels" of mortgage lending the key constraint on market growth in the near term."Whilst the group will benefit from the opening of c. 110 sites during the second half of FY 2010/11, we anticipate that any volume growth for the year will be limited," it says.