Saving Face

Restoring Cast Iron Facades for a Modern World

Overview

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Abstract

In 1871, a fourth level Architecture course was offered in New York City that instructed on topics such as heating, ventilation and circulation of water. Notably, it asserted that the only way to successfully ventilate a building was to use fuel. Fast forward 150 years and we find that we are battling this same concept, while simultaneously forcing our historic buildings to perform within modern energy limits.

During the Reconstruction Period (1865-77), New York City saw the erection of numerous buildings where cast iron was used as the primary material for the main façade. The cast iron cladding, used in conjunction with structural cast iron elements, allowed facades to consist of up to 50% window openings. One such building was a commercial office and storage building just below Houston Street, and another, a smaller department store building in the fashionable shopping district of 6th Avenue.

While once considered to be prime examples of standard cast iron facades, each structure suffered the ravages of time. The commercial storage space became a garage, with several cast iron elements removed to accommodate garage openings and car elevators. The other had a large fire escape anchored to the face of one elevation, while the other elevation was “trimmed” back to allow an aluminum rainscreen to be attached.

Between 2016 and 2019, each of these buildings were renovated and the facades restored back to their original state. However, designing the facades to function at current thermal performance standards proved challenging. The structural cast iron columns act as major thermal conduits, and the addition of insulation introduced the potential for excess moisture in the wall assemblies. Consideration was also given to the limitations of the historic metal, including its natural inconsistencies due to historic manufacturing techniques.

This presentation will explore the restoration, conservation and applied building sciences that were required to rehabilitate these historic metal facades as well as a discussion about the limitations encountered when trying to achieve modern standards with historic materials.

Introduction

In 1871, a fourth level Architecture course was offered in New York City that instructed on topics such as heating, ventilation and circulation of water. Notably, it asserted that the

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Background

Two cast iron façade buildings were used as case studies for this research, both buildings are in the Manhattan borough of New York City and were constructed just after the

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Methods/Findings

As a means to understand how these buildings were thermally improved, THERM, WUFI and Comcheck analyses were completed, using modeling from before the restoration and after. THERM is a two-dimensional

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Explanation

Using both the THERM and WUFI analyses for the new proposed wall system indicated that the addition of insulation moved the temperature transfer zone further towards the exterior cast iron—from

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Conclusions and Future Work

Managing energy expectations when restoring historic buildings is crucial. There is a general notion in the restoration industry that through the full renovation and restoration of historic buildings that historic

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Acknowledgements

Many thanks to Taras Yavorskyi and Angel Lugo for preparing the before and after THERM and WUFI models for this research.

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REFERENCES

Castele, Daniel S. and Amanda L. Webb. Association for Preservation Technology Bulletin Volume 50:1, (2019) “Insulating the Walls of Historic Buildings: A Systematic Review of Existing Guidance.”

Arnold, Koti, Tuner and Ahuja. Association for Preservation Technology Bulletin Volume 50:1, (2019) “Applications and Validation of Building Performance Analysis.”

Artigas, David and Sean O’Brien. Association for Preservation Technology Bulletin Volume 50:1 (2019) “Energy, Hygrothermal, and Freeze-Thaw Considerations for Insulating Mass Masonry Walls”.

New York City Landmarks Preservation Commission. SoHo-Cast Iron District Designation Report, City of New York (1973).

New York City Landmarks Preservation Commission. Ladies Mile Historic District Volume 1, Designation Report, City of New York (1989).