US STOCKS SNAPSHOT-Futures add to gains after prices data

NEW YORK Aug 16 (Reuters) - U.S. stock index futures added to gains on Tuesday after data showed producer prices rose in July for the first time in four months, easing deflation fears.

S&P 500 futures SPc1 rose 8.3 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures DJc1 gained 52 points and Nasdaq 100 futures NDc1 added 12.5 points.

Separate data showed U.S. housing starts rose but to a much weaker rate than expected in July, while permits for future home construction fell to their lowest level in more than a year.