Accoya® wood specified to restore historic windows in Minnesota State Capitol

The majestic State Capitol building in St. Paul, Minnesota was in a state of deterioration: on the outside, the regal marble exterior design, completed in 1905, was crumbling.

The state embarked on a $272 million, four-phase restoration plan in 2013, with tasks including replacing plumbing and electrical systems, boosting energy efficiency, improving access, replacing the roof and repairing all of the crumbling stone.

Another major part of the project was restoring the building’s original wood windows, which had been covered over with aluminum windows 30 years ago. The aging units—242 in total—had seriously suffered from fogging, failing glass, air leakage, and broken balances that rendered them inoperable. Window replacement manufacturer Re-View, were selected to restore the windows and bring the Capitol building back to life.

Re-View removed the aluminum units, revealing the original wood window frames, which were then restored using restoration epoxies and replicated Accoya wood parts. Re-view used an original complete wood window that still remained in the building as the basis for the designs and to help replicate all the new sashes with Accoya wood. Re-view chose Accoya due to its durability and 50 year guarantee.

Since some of the individual double-hung windows are about 2 meters (6 feet) wide by 4 meters (13 feet) tall, the sashes weigh in excess of 115 kilograms (250 pounds). This resulted in the Re-view team engineering a system of weights and pulleys to make the massive windows easy to open. Many of the Accoya installed windows were tested for air and water infiltration by an independent testing agency and it was determined that they were twice as tight as the published ratings for modern replacement windows.

As forecasted at the start of construction in 2013, the work will be completed in June 2017.

Project details:
Project Owner – Department of Administration, State of Minnesota
Contract Administrator – CPMI (Cost, Planning and Management International)
Program Manager – MOCA Systems
Design Team – HGA Architects and Engineers
Construction Manager – JE Dunn Construction
Governing Body – Minnesota State Capitol Preservation Commission

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