Precision Board Replaces Sheet Metal Architecture on Church Built in 1841

Calling it “one of the most technically challenging projects of his career,” the 40 foot long balustrade Will Williamson made for Old St. Mary’s Church in Detroit, MI is an incredible feat of craftsmanship.

The church, built in 1841, had a once magnificent sheet-metal balustrade that had deteriorated over the years and was about to collapse into the street 30 feet below. Having performed much work for the Catholic Archdiocese of Detroit over the years, Will, owner of Williamson Lumber and Millwork, was confident he could offer a long-lasting solution for the church.

18 OSM 30 feet off the Ground


4 Old St Mary before

1Old St Mary before
Original balustrade, note sheet metal erosion.

With over 15 years of experience using Precision Board on a variety of projects, Will figured it would be the perfect long-lasting substrate for this project. Also, because Precision Board is available in 5′ x 10′ sheets, 2, 3 and 4 inches thick, he could CNC cut and shape all of the large ornate details easily.

“I chose to use Precision Board HDU on this project because it’s such a stable material that I knew could withstand the rough Michigan weather. When I received my Precision Board Plus shipment, it was the middle of December and about 10 degrees outside. The first thing I did was open the package and measure the sheets before we brought them inside. There were 10 5′ x 10′ sheets, 2″, 3″ and 4″ thick. When I measured the last 4″ sheet 6 months later in June, it was pushing 90 degrees. The sheet had only moved 1/16th of an inch in the 10′ length and about 1/32″ on the 5′ end. That’s when I knew I had made the right decision going with Precision Board for this project,” says Will.

Using his American-made Thermwood CS45 CNC router, Will designed all the architectural details in Autocad and exported the dxf files directly to Thermwood’s e-Cabinet Systems 3-D design software.

Screen Shot 2014-08-05 at 4.19.30 PM

9 OSM Balusters

Inside e-Cabinet, 3D parts were created and nested onto 5′ x 10′ sheets of Precision Board Plus. This resulted in a very efficient use of materials with very little scrap. When everything was finished, Will had 32 6″ x 6″ balusters, 4 24″ square newels with recessed panels, and 40′ 12″ x 6″ hand and foot rails.

After all the Precision Board was machined, it was primed with FSC-88WB Primer/Filler and finished with Sherwin-Williams paint.

Before installation began, Will removed all remnants of the previous metal balustrade.  Will and crew built new pressure treated pedestals underneath where the newel posts would lie, and had a new rubber roof installed.

The newel posts were made by building a white oak frame and surrounding it with CNC routed Precision Board pieces that were engineered to lock in place because Will did not want to bond the dissimilar materials together due to different expansion and contraction rates.



Because the 40 foot length of the balustrade exceeded the space in his shop, the entire piece was pre-assembled and painted in Will’s driveway. Midway through the project, Will suffered a Quad-Runner accident and broke his wrist. Frank, his son, stepped in and tackled the planing, jointing and assembly of the 2″ thick White Oak frame, pre-fitting the entire assembly.

17 OSM White Oak Frame2

When installation time came, the white oak newel bases were set onto the new rubber roof, followed by slipping the HDU down over the base.

A crane was then used to lift the pre-assembled railings into place and the framing was fastened to the newels. A final caulking of the joint where the balustrade contacted the building and the project was finished! This project was officially completed in 2009, though it was over 2.5 years prior to that when talks began!


For over 40 years Williamson Lumber & Millwork has been a licensed and insured State of Michigan contractor, and their projects have included everything from church restoration, to sign making. Will Williamson started his trade as an apprentice rough carpenter and progressed into finish carpentry contracting. In 1985, Will started Williamson Lumber and Millwork, producing architectural millwork and selling kiln-dried hardwood lumber.

Will’s reputation for fine work has seen him undertake projects for the Archdiocese of Detroit along with major motion picture studio Paramount Pictures. Currently, Will has been commissioned by the Arch Dioceses of Detroit and is in charge of designing and building an entirely new TV set for the Mass Shutins TV show (channel 2 in Detroit!).

Please see additional information on Will’s website,