The building retrofit market is big business. With around 130 million buildings throughout the United States (5.5 million of those commercial, according to a U.S. Energy Information Administration Commercial Buildings Energy Consumption Survey) and a push to reduce carbon emissions in the built environment, the glazing industry is flush with retrofit opportunities.

The Lever House’s updated curtainwall features concealed aluminum glazing channels, stainless steel mullions and caps and new lites of heat-strengthened glass. Photo: Wikimedia.

However, curtainwall and window retrofits are difficult, requiring glaziers to consider numerous factors before refurbishing, recladding or overcladding a system.

According to Todd Frederick, president of Wisconsin-based FreMarq Innovations, the best way to navigate a curtainwall retrofit is to assess the current system and communicate the proper steps. FreMarq supplies and installs a retrofit system that enables building owners to re-skin a curtainwall system without removing the existing framing.

“I always start by inspecting the existing curtainwall,” says Frederick. “I also look at how long it has been installed, what type of glass is installed and what issues the building owners are experiencing with the existing wall. For instance, is there condensation, a leak or air intrusion?”

Frederick explains that FreMarq will do an initial tearout to observe what’s behind the wall. If the building owner wants to save the existing curtainwall frame, glaziers will deglaze the system and apply a new thermal barrier over the existing curtainwall. However, Frederick says that once the system is deglazed, glaziers must inspect insulation in the spandrel areas, check for back pans, and look for vapor barriers, among other things.

“We’re looking at a curtainwall that was installed in 1955,” says Frederick. “We did our examination a few weeks ago and found that the anchors holding it in place are broken from the building. You have to see how it is currently attached to the building and where you can reattach it. Is the structure strong enough? You just don’t know with some of these curtainwalls built in the 1950s.”

Frederick says all these issues can be resolved if proper steps are followed and completed in a particular order. Aside from the technical and installation challenges, retrofits are costly, especially for curtainwalls built in the 1970s and earlier (curtainwalls last for around 50 years). Frederick says those projects are usually tearouts, adding that tearouts are the most common curtainwall retrofits he has encountered. The most frequent projects he works on are office buildings and hospitals, which have many issues with condensation.

One such office building in New York recently underwent a full renovation carried out by Skidmore, Owings & Merrill (SOM). The Lever House renovation was completed in late 2023. The process started in 2001 when SOM restored its façade after the iconic curtainwall suffered water damage throughout the years.

SOM officials explain that water had seeped behind the steel mullions, causing the carbon steel within the glazing pockets to rust and expand. The resulting corrosion bowed the horizontal mullions and broke most of the spandrel glass. Officials say the updated curtainwall features concealed aluminum glazing channels, stainless steel mullions and caps and new lites of heat-strengthened glass.

“The project is a primary example of how we can extend the life, vitality and sustainability of our existing buildings, which ultimately is the most sustainable thing we can do as a culture,” says SOM partner Ken Lewis.

New technologies and laws, including vacuum insulating glass (VIG) and New York’s Local Law 97, have made curtainwall retrofits more desirable and frequent, which is good business for glazing companies.

“I’ve noticed in the past six months that there have been more requests for retrofitting,” says Frederick. “I think the economy has something to do with that. I do think everyone wants to do the right thing and reach sustainability goals. To do that, they need to start moving now.”

Leave a Reply

Your email address will not be published. Required fields are marked *