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Stoneleigh Estate - Renovations of The Main House
Publication Date
February 25th 2019

Maintaining a Historic Perspective

Renovations to the Stoneleigh Estate’s Main House on Philadelphia’s Main Line provided modern upgrades while being sensitive to the home’s classic aesthetic


The Main House on the Stoneleigh Estate is a historical structure that was built in at the turn of the 20th century in Villanova, Pennsylvania. It was the former residence of the Hass family. The family donated the 19,000-square-foot Main House, along with its 42-acre property, to Natural Lands in 2016 so that the property could be converted to a public garden for all to enjoy. Today, Stoneleigh: a natural garden—which bears the imprint of a number of notable landscape architects including the Olmsted Brothers, sons of the famed Frederick Law Olmsted—is a stunning reflection of more than a century of horticultural conservancy.


“Since my first visit about 20 years ago, I have always loved Stoneleigh,” said Jane Pepper, a member of Natural Lands’ Board of Trustees and former president of the Pennsylvania Horticultural Society, in a statement.


“The stately trees, the wide expanses of lawn, and the elegant architectural features make this a special place, and I’m so grateful to the Haas family for making it available for future generations to enjoy.”
- Jane Pepper

The design team’s goal for Stoneleigh’s Main House was to repurpose the historical building to accommodate the institutional headquarters for the Organ Historical Society. The organization required renovations to the mansion that included office spaces, a library, and historical archival spaces. Other restructurings of the residence included administrative spaces for Natural Lands, an organ pipe chamber, and a new commercial kitchen and catering venue to serve as a space for public events. In addition, a 1931 organ located in West Orange, New Jersey, was relocated and installed in the Main House.


Stoneleigh Estate Main House Back

Sustainable Updates

The original air conditioning systems of the main house were not up to the standards of the modern amenities that are used today. It was important to keep the structure’s historical integrity, and new HVAC systems were a vital part of preserving the building’s interior and contents. A thoughtful and sensitive approach led to the installation of archival-level climate control HCAV systems. Non-invasive mechanical system distributions were designed to conceal and minimize interior disturbances, bringing the building up to modern standards while preserving its historic decor and aesthetics.


For critical areas such as historic archival spaces and the rare books library, the unique HVAC systems included precision cooling, heating, and humidity control equipment. This was to maintain the desired temperature and relative humidity criteria within tight tolerance, as required by museum and archival standards. These spaces included a new interior envelope with continuous vapor barriers and gasket doors. Each space was designed as an independent zone with its own air handling unit, space controls – including thermostat, humidistat, monitoring, and fault alarms.


The new MEP/FP systems, distribution, and lighting for the Main House’s renovations took into account areas of high interest and concern to keep the disturbance of historical features to minimum. Specialty lighting – with lighting controls – were installed for aesthetic spaces on the ground floor. General illumination design was provided for other spaces. New electrical service was implemented to support the property and garden’s necessary modern upgrades. The existing garage was transformed in to an electrical space with electrical panels, switch gears, transfer switches, and a back-up outdoor generator. Provisions were made for a new fire alarm system, low voltage systems – including audio/visual, telephone/data, and security – and site power/lighting.


In addition, the design team installed a 1931 pipe organ for the resident Organ Historical Society. The Aeolian-Skinner Opus 878 serves as a lynch pin for the renovation’s plan to unite nature and music, as desired by the Haas family. The organ’s 2,218 pipes were installed in the basement, allowing the pipes’ bellows to be heard throughout openings in the floor as the organ is played in a room off the house’s foyer. Older basements are less-than-ideal environments for such a sensitive instrument due to damp and cold conditions, so extra care had to be provided in the design.


Stoneleigh Estate Inside Lighting

Stoneleigh Estate Inside Lighting2

stoneleigh estate inside lighting3

stoneleigh estate organ room

Fire Safety Retrofitting

An important part of Stoneleigh’s renovation was the facility’s new fire protection systems. Having so many historical elements, it was important that the Main House’s new design be sensitive to its interiors. Provisions were made for a new fire protection system that encompassed the entire house. The fire protection system included a wet system for all non-critical spaces that required detailed pipe routing, as well as concealed sprinkler heads for spaces of high interest that have original decorative ceilings and moldings. Critical areas, such as historical archival spaces and the organ pipe chamber, were provided with a dry or non-water based FM-200 fire suppression system. A new fire pump was installed to provide the required flow and pressure for the new fire protection systems.


Stoneleigh: a natural garden is now open to visitors, free of charge. While Natural Lands’ places emphasis on the beautiful green spaces and garden elements, the Main House is sometimes used for events and gatherings. It is critical that the building remain safe and accessible as visitors come to experience the historical structure in person. The new fire protection systems are an important part of making this happen, as the grounds are sure to have many guests in the future.


Exemplary Historic Preservation

Thanks to the careful renovations by the design team, which included John Milner Architects, and Urban Engineers – who provided MEP/FP engineering services – patrons can now visit Stoneleigh: a natural garden and experience its historic cultural value. The recent upgrades to the facility will allow that experience to be shared for generations to come.


“Stoneleigh is unique among our preserves in so many ways,” said Molly Morrison, former president of Natural Lands, to the PhillyVoice. “We envision a place where the public will be able to enjoy the quiet and beauty of the Stoneleigh grounds and be motivated to learn about the joys and benefits of gardens that emphasize the use of native plants. We are deeply honored to be entrusted to carry on the Haas family’s legacy of stewardship for this magical place, and excited beyond measure to add Stoneleigh as a unique, shining star in our constellation of preserves."


Get in Touch
Vice President, General Manager, Facilities & Building Systems 215.922.8080