WASHINGTON—U.S. construction spending increased less than expected in December as a solid rise in private projects was partially offset by a sharp decline in outlays on public projects. The Commerce Department said on Tuesday that construction spending rose 0.2 percent after advancing 0.6 percent in November. Economists polled by Reuters had forecast construction spending gaining 0.6 percent. Construction spending increased 9.0 percent on a year-on-year basis in December. It rose 8.2 percent in 2021. Spending on private construction projects rose 0.7 percent in December. Outlays on residential construction surged 1.1 percent. Single-family homebuilding spending accelerated 2.1 percent, while outlays on multi-family housing projects rose 0.4 percent. Homebuilding remains constrained by higher prices for building materials, especially framing lumber. The United States last November nearly doubled the duties on imported Canadian softwood lumber to 17.9 percent from 9 percent after a review of its anti-dumping and countervailing duty orders. Residential investment …