* Trading in-line with expectations
* Q3 Total LfL sales per trading day down 3.5 pct
* Q3 total sales down 2.4 pct
* Trading improved in Sept, on target to meet marketexpectations
* FD Paul Hampden Smith to step down in Sept, 2013(Adds details)
LONDON, Oct 12 (Reuters) - British builders' merchant anddo-it-yourself retailer Travis Perkins posted a 3.5percent decline in underlying sales after poor weather and toughcompetition crimped trading in its third quarter.
The firm, whose brands include City Plumbing, Keyline, TileGiant, BSS and Wickes, on Friday said like-for-like sales in theperiod to September 30 were down in all but one of its fourdivisions, although sales had improved at the end of thequarter, with plumbing and heating boosted by colder weather.
Third-quarter turnover at builders merchant depots open morethan a year fell 1.6 percent and was down 4.7 percent at itsplumbing and heating unit. Like-for-like sales were down 7percent at its home improvement business, while its specialistmerchanting division posted a 1.3 percent rise.
The group said it remained in line to meet marketexpectations, although it had increased its cost management tohelp ease margin pressure across its merchanting divisions.
Though both construction and consumer markets have been weakin the economic downturn Travis Perkins has performed relativelywell. In July the group posted a 7.3 percent rise in first halfprofit despite taking a 10 million pound hit due to recordrainfall disrupting activity at building sites.
British construction activity, not helped by a spate offlooding across the country, contracted for a second straightmonth in September as business morale held close to its lowestsince entering recession in 2008.
Travis Perkins, which also said on Friday its financedirector, Paul Hampden Smith, would step down next September, isexpected to post a full-year pretax profit of 309.5 millionpounds according to a Reuters poll of 19 analysts.
Shares in the FTSE 250 firm closed at 1135 pence onThursday, up 35 percent on a year ago, valuing the business ataround 2.7 billion pounds.
(Reporting by Neil Maidment; Editing by Paul Sandle)