According to two recent studies by the NAHB building materials have gone up 5% since the beginning of the year. But that's just an average; increases vary by region and have been greater for certain materials…
The South and West have seen greater increases than other parts of the country. Framing lumber, OSB, plywood, gypsum, trusses, ready-mix concrete, and roofing are up more than plumbing fixtures, brick, and steel.
An article in Builder gives the following explanation for why this is happening, even though homebuilding is only halfway back to normal levels:
"Manufacturers of building materials experienced the same collapse in their markets as builders did. After ramping up capacity to supply the construction of more than 2 million homes a year, home building fell to barely 0.5 million. All of the resources, labor, factories, trucks, raw materials, and capital went idle or found other industries or markets. For instance, timber went to China, workers went to energy production, and manufacturing facilities were scraped.
As production comes back, these resources will return but it will take time. The slow housing rebound may be a blessing in disguise giving the rest of the housing support system time to rebuild."