Homebuilders were more confident in January than in December, according to a survey from the National Association of Home Builders. That marks the third consecutive month of confidence gains.

The survey says it’s mostly because demand for housing is strong and mortgage rates are lower than they were late last year. That said, the survey found that construction companies are still having a hard time securing the building materials they need.

It’s been especially hard to find sophisticated equipment lately, reported John Kirk, founder of the Lightpath Co., a multifamily developer based in New Braunfels, Texas. That includes transformers, circuit breakers and electric meters.

“Anything that has a chip in it — your [heating and air conditioning] equipment, air handlers, compressors,” he said.

There’s high demand for that kind of equipment, Kirk said, because a lot of construction projects kicked off a few years ago. More recently, they’re moving out of the planning and design phase.

“Once you start construction, you start buying out the materials and assembling and building the project,” he said.

Other, more basic materials, like lumber and steel, are getting easier to find and cheaper. But there’s still a shortage of skilled labor and available lots, according to Susan Wachter, a real estate professor at the Wharton School.

The result: “Labor costs have increased, and land costs are still increasing,” she said.

That’ll continue to put pressure on the cost of housing, Wachter added — especially while demand for new homes stays high.