The May report on material prices and demand has good news and bad news for builders. The good news is that the residential construction industry shows no sign of slowing. But a number of forces, including tariffs, petroleum prices, and rising material demand from places such as China and India, are driving material prices higher, according to Ken Simonson, chief economist for the Associated General Contractors of America. He describes U.S. distribution channels as “tightly stretched,” with shortages of cement likely this summer in many regions.