Case Studies – Temporary Climate Solutions

Speed up construction schedule with concrete drying

Construction drying is vital in times of need, especially when running on a tight schedule. Best Buy's Portland retail store found themselves in this exact situation when construction issues threatened their project schedule.

Joe Schueller, a construction superintendent for S. D. Deacon, found himself in a challenging situation. He had a tight deadline to complete a project involving more than an acre of concrete flooring that needed to be finished with VCT tile or glass back carpeting. The flooring contractor wouldn't guarantee the adhesion of the floor coverings if the concrete wasn't dry, and the customer wanted to shorten the construction schedule by a week. Schueller realized that conventional methods would take too long to dry the concrete adequately.


“I had more than an acre of concrete that I needed finished with VCT tile or glass back carpeting,” said Schueller. “The problem was that the flooring contractor wouldn’t guarantee the adhesion of the floor coverings if the concrete wasn’t dry. On top of that, the customer wanted to shorten the construction schedule by a week! When I started looking for a solution, I knew conventional methods would take too long.”

The new Best Buy retail store in Portland, Oregon was scheduled to be completed four weeks after the building was closed in. Sheetrock, painting, and flooring were scheduled to go quickly, but high levels of interior humidity and moisture trapped in the concrete floor and masonry walls were proving a difficult problem.

“I don’t think Joe thought desiccant drying would work,” said Garrett Freeman, Polygon industry sector manager. “Dry air is invisible. Many of our customers have a healthy skepticism at first, but the proof is in the results.”


Concrete is evaluated for moisture content using a calcium chloride test. Calcium chloride, a highly hygroscopic salt, is exposed to the concrete under a small plastic dome that is sealed to the floor. The amount of water it absorbs in a specific time is measured to determine how dry the concrete has become.

“Our floor measured 8.6 pounds,” said Schueller. “We needed to lower the moisture content to less than 5 pounds before flooring could be adhered and guaranteed to stay down.”

Polygon tackled the Best Buy project using industrial desiccant dehumidifiers. They readily adapt to a variety of available utilities, operate at any temperature, and dry without the need for heat.

Polygon’s high-volume dehumidifiers produce extremely dry air that is circulated inside the building. The air pulls moisture molecules out of substances like concrete, masonry block and joint compound, allowing them to dry in record times.

At Best Buy, Polygon used three construction dehumidifiers, distributing dry air with a network of flexible ducts. The set-up allowed work to continue inside without encumbering any other activities.

Not only did the floor reach a safe moisture content for tile and carpet to be adhered, but unexpected advantages emerged as by-products of the drying process.

“For example, the building needed the masonry block walls sealed and painted,” said Freeman. “The wall had soaked up water during rainstorms which occurred before the roof was completed. With February weather outside and high humidity from the floor inside, there was no way that wall could dry on its own. But as we dried the floor, the wall also dried.”

Joe Schueller was impressed with the effect that drying had on the drywalling work schedule. “I’ve never seen drywalling go faster,” said Joe. “The progress was incredible; drying cut days out of the drywall effort.”

In three weeks, the concrete slab had dried down to 4.4 lb/1000 square feet/24 hrs according to Schueller. “One thing you can’t do in the construction business is miss the deadline,” said Schueller. “We didn’t, thanks to Polygon. If I were in a similar situation, you can bet I’d call Polygon back.”