* Boral posts record profit, lifts dividend
* Infrastructure drives Australia earnings over expectations
* Shares jump 10 pct to four-month high (Recasts and adds market reaction, analyst and CEO quotes)
By Tom Westbrook
SYDNEY, Aug 29 (Reuters) - Australia's largest building materials supplier Boral Ltd BLD.AX posted a record annual profit on Wednesday, thanks to earnings from a new division in the United States and an infrastructure boom offsetting Australia's cooling home market.
In the first full year since it bought U.S. fly-ash maker Headwaters, net profit to June 30 rose 38 percent to A$473 million ($346 million), slightly ahead of analyst expectations, giving its shares their best day in more than nine years.
In its largest market, Australia, Boral posted double-digit gains in revenue for concrete and asphalt, its biggest earners, as drought conditions that have hurt farmers meant good going on huge roadmaking projects along the east coast.
The result underscored how the company's exposure across the building sector, from renovation supplies like roofing to pouring concrete at freeways, has insulated it from a downturn in home construction.
"Volumes from commercial, infrastructure and major projects activity, and margin improvements are expected to more than offset the impacts of a moderating residential construction sector," Boral Chief Executive Officer Mike Kane said.
Boral's domestic earnings of A$370.4 million were 6 percent above Goldman Sachs' forecast, pushing its shares up more than 10 percent to a four-month high and helping the broader market .AXJO rise 0.5 percent.
Single-family homebuilding in the United States hit its highest level in a decade during the financial year, and while it has slowed a little, Boral expects remodeling to drive continued demand for its products. Australia, where the housing market has been a major driver of an economy that has grown for 27 years without a recession, a recent weakening has some economists warning of heightened risks of a downturn. a road and railway building boom, driven by state government asset sales, is driving steady demand for concrete.
"We think investors were cautious going into the result," UBS analysts wrote in a note to clients, which said the numbers, plus "solid guidance" were positives. Macquarie analysts said it was a "solid operational outcome".
Boral expects growth from all its businesses in 2019, with strong housing starts and benign weather expected to lift core earnings in North America by at least 20 percent and margin improvements expected in Australia.
Total revenue rose by a third to A$5.9 billion.
The company announced a final dividend of 14 cents a share, up from 12 cents last year. ($1 = 1.3669 Australian dollars)