Housebuilding and construction group Galliford Try reported a first half profit, helped by a stronger construction order book but warned the market remained challenging.The group posted pre-tax profit of £6.4m in the six months to end December compared to a loss of £37.5m the same time a year before. Group revenue fell to £570m from £774m before. The contracting order book was up 6% at £1.8bn.Commenting on trading, chief executive Greg Fitzgerald noted, "While the board remains cautious on the overall economic environment, with a strong balance sheet and sector leading cash resources the Group is well placed to take advantage of opportunities across its activities as they arise."Galliford said the average selling price was up 2.8% year-on-year in the first half, with completions expected to pick up sharply in the second half.The dividend maintained at 3.3p per share.