New Jersey State House Undergoes Restoration


Global manufacturer of dry, low dust, recyclable abrasive blasting media and related equipment Sponge-Jet (Newington, New Hampshire) was recently reported to have played a role in a $300 million historical preservation and renovation project at the New Jersey State House.

According to reports, work on the project involved restoring the structure’s gold dome, which called for surface preparation, new coatings and the application of gold leaf.

About the State House

Designed by Jonathan Doane and built in 1792, the site of the New Jersey State House initially spanned nearly four acres and cost 250 pounds (about $304) to erect. At the time, the building was comprised of two and one-half stories and included a bell tower as well as several bays radiating off from the center hall.

While the government would continue to grow in numbers over several decades following the construction of the State House, it wouldn’t be until 1845 that the building underwent any alterations or additions. That year, Philadelphia-based architect John Notman designed a three-stepped office wing on the north side of the original building.

The new entrance reportedly featured a two-story porch and fluted Doric columns.

Twenty years later, the river-side portico was extended. Additional work carried out by Samuel Sloan included the modification of the west wing and new wings for each legislative house.

In 1885, a fire destroyed the West State Street wing of the structure. That same year, Lewis Broome of Jersey City was brought on to plan the reconstruction. The replacement was carried out in a Second Empire style with three stories and limestone facing. Broome also added a new rotunda and dome, which still stand today.

In 1891, the Assembly wing was replaced with a more Victorian style structure designed by Assemblyman and architect James Moylan. In addition, Moylan also constructed an addition to the west end of the original 1792 structure to create private offices for the governor and judges.

A third floor was also added to the south end of the center wing. Several years later, the wing was extended. The addition was designed by the architectural firm of Karr, Poole and Lum with Assemblyman George Poole as one of the firm’s principals.

Under the direction of Arnold Moses, the Senate wing was reconstructed in American Renaissance style to mirror the Assembly quarters in 1903. Three years later, the original 1792 east wing was replaced with a four-story office section, while the front section was extended in 1911. The west side was again extended the year after that.

In 1987, the New Jersey State House launched a major renovation project. Upgrades included the restoration of the legislative portion of the building and added legislative office space, known as the South Addition. At the time, the State House Annex was also renovated, and a pedestrian tunnel and multi-level parking garage were constructed.

A public-private partnership allowed for the golden dome and interior rotunda space to be refurbished. A welcome center, cafeteria and landscaped plaza were also added during the restoration project.

Most recently, in 2017, the front portion of the New Jersey State House, including the Rotunda, was closed for renovations. While work is still underway, officials estimate that the project will reach completion sometime in 2023.

The work is being done by Preservation Design Partnership as contracted by the New Jersey Building Authority, with funding provided by the New Jersey Economic Development Authority.

An overview of the project can be accessed here.

Dome Restoration

G.C. Zarnas & Co Inc. (Bethlehem, Pennsylvania) was recently tasked with the restoration of the 160-foot-tall (from floor to apex) cast iron dome structure at the New Jersey State House.

“Our scope of work was to remove all existing coatings on the substrate down to bare metal and install a new coating system,” said an unnamed project manager and estimator for G.C. Zarnas & Co Inc. In addition to the removal of the old and failing coating, the contractor was also tasked with the removal of all corrosion and oils, soluble salts and other environmental contaminants from the substrate.

According to reports, because the historic preservation and restoration project would take place at heights and over a busy downtown area, traditional abrasive blasting was not an option for the contractor.

“Sponge media blasting is a much cleaner process in terms of dust and given that the job was in the middle of downtown, keeping airborne debris to a minimum was a necessity. It also is less harsh on the substrate than traditional abrasive blasting. This ensures that damage was not done to the underlying historic cast iron structure,” explained the G.C. Zarnas team.

In its report, Sponge-Jet shared that, unlike traditional abrasive media, sponge media is reusable, allowing for a significant reduction in media consumption and disposal. In addition, the reduced weight was critical for contractors working on scaffolding for the State House project.

According to the contractor, the biggest challenge on the job was staging the equipment.

“We ruled out putting the equipment on the roof as an option, so we had to put all equipment on the ground level,” officials said. “We ran 100 plus feet of hose to reach the top of the dome. We also had to have a compressor large enough to push air all of the way through without losing too much pressure at the nozzle.”

Members of the team also noted that this challenge would have been much more difficult if traditional abrasive media was used instead of sponge media. 

Once the surface prep was complete, the crew applied a new coating system supplied by Tnemec. The system consisted of four coats: a zinc-rich primer, epoxy patching of small dents and dings to the metal, an intermediate protective coat and a fluoropolymer topcoat.

In the final stages of the project, restoration experts and winners of the 2021 Elevation Awards Evergreene Architectural Arts applied gold leaf to the exterior section of the structure.


Tagged categories: Architecture; Commercial / Architectural; Completed projects; EverGreene; Government; Historic Preservation; Historic Structures; Maintenance + Renovation; NA; North America; Project Management; Projects - Commercial; Renovation; Restoration; Restoration; Sponge blasting; Sponge-Jet; Surface preparation; Tnemec

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