Construction volume is not the same as construction spending.

Spending is the number nearly everyone follows. Volume is spending minus inflation.

Two years that show the greatest differences between spending and volume highlight the affect of inflation. In 2004 and 2005 total construction spending grew by 11% and 12.5%, but after inflation, volume grew by only 3% and 2%. In the most recent year, construction spending in 2015 grew by 10.5% but total construction volume grew by only 7.5%.

For the four years 2012 through 2015 construction spending grew by 35% but after inflation volume grew by 21%. Inflation accounts for 14% of spending growth.

Annual construction inflation varies for residential, nonresidential buildings and nonresidential infrastructure, and it varies sometimes so widely that each should be used only to adjust that specific group. Since 1993, long-term annual construction inflation for buildings has been 3.5% per year, even when including the recessionary period 2007-2011. During rapid growth periods, inflation averages more than 8% per year.

Historical average volume growth over the last 22 years is grossly distorted by the recession. Volume declined in 8 of those 22 years. In the worst three years of the recession, 2008, 2009 and 2010, volume declined by 28%. If we take out those three years the typical growth period averages are more apparent. The historical average volume growth in construction with recession data removed and after adjusting for inflation is 2% per year for 19 years.

Adjusting for inflation is changing current dollars to constant dollars.

Current dollars = dollars are reported in the value of the year reported, 2008 = 2008$, 2015 = 2015$. News reports almost always refer to current dollars and therefore do not account for the influence of inflation.

Constant dollars = all dollars adjusted to represent dollars in the year of comparison. This adjusts for inflation so 2008$ (and all other years) are converted to equivalent 2015$.

It’s not too hard to understand why we need to look at constant dollars when you think of it in terms of building a house. For example, a 2,500 sf house built in 2001 may have cost $250,000 then to build. Today to build that exact same house may cost $400,000. The house is no different, so volume remains the same. The only thing that changed is inflation. With respect to constant dollars for the same volume, $250,000 in 2001 dollars would be equal to $400,000 in 2015 dollars.

The common comparison is to look at growth in construction spending from year to year. What that does not tell us is how much of the spending growth is inflation and how much is a real increase in construction volume.

Constant dollars makes a huge difference in the analysis. Adjusting all previous years of spending allows us to compare changes in volume growth from year to year. This plot of total construction dollars shows current dollars would indicate we are now only 7% below the previous high and we’ve had growth of 37% from the recession low. Constant dollars, adjusting for inflation, shows volume is still 17% below the previous cycle high and we’ve had growth of only 22% since the recession lows.