Reglazing Modernism: Intervention Strategies for 20th-century Icons

I discovered by working with actual glass models that the important thing is the play of reflections and not the effect of light and shadow as in ordinary buildings  
Ludwig Mies van der Rohe[1]

Should We Save Mid-Century Modern Icons That Hurt The Environment?
James Timberlake,  2015[2]

Reglazing Modernism

Between the above quoted poetic remark by star architect Mies and sceptic recent observations of  architect James Timberlake, manoeuvre the authors. The publication, by Birkhäuser Architecture in a German and an English edition, introduces itself as the first one of a serial. The list of examples (nine in USA and eleven in Europe: GE 4, NL 2, FR 2, UK 1, CZ 1, RU 1)[3] reveals the high complexity of the undertaking by three authors. They, Angel Ayón Uta Pottgiesser and Nathanial Richards, introduce to the reader the specificity of reglazing Modern Movement architecture.

The chapter Case studies – Intervention Categories clears much about the subject reglazing. The authors define three levels, the first being the least evasive for the original material substance: (1) Restoration – Steel repairs and single-pane glass replacements, (2) Rehabilitation – Glass replacement with IGU (insulated glass unit) or addition of secondary glazing and (3) Replacement – with (non)thermally broken steel or aluminum frames. As the book documents all these categories need a lot of analyses, design efforts and superb hand craft. Every case study starts with a general description, a timeline chronology on interventions in the building and changes in ownership, 3D details explaining before/after restoration. They conclude with comments of a refreshing kind, showing a pragmatic view with mild conclusions. Carefull established diagrams help comparison of the case studies.

A feature of this grand survey is that the network of practicioners and scientests is large. On the other hand the network turns out to be relatively recent, compared to “100 year Bauhaus”. The moment of deeper interest of “reglazing Modernism” is related by the authors to the very start of docomomo conferences in 1990[4] and to technology seminars by the docomomo International Specialist Committee – Technology (chaired since 2016 by co-author Uta Pottgiesser). One learns that the topic became raised when architectural monuments became listed as local or world heritage. From that instance on the owner is confronted with the technical issue of reglazing Modernism because the natural life span of the windows had finished. On top of that the expected performance in building physics, also in respect to climate change, was not achieved. In result the range of disciplines involved raised, along with competence disputes: architects, material conservators, engineers on statics and building physics, heritage administration, funding specialists, and more. In the case of Tugendhat house[5] the growing complexity of the restauration urged the Chech authorities to establish an international committtee of experts called Thycom to consult the whole process.

It is a kind of pitty that the authors do not bring cost factors in detail, preventing thus “the disclosure of confidential or unpublished information” (p. 27). In general one can say that true costs are very difficult to calculate, since many of the architectural offices and glass firms participate in academic research sponsored by the public hand and various organisations. Such private non-profit foundations are in Germany the Wüstenrot Stiftung (Hamburg) and in the USA the Getty Foundation (Los Angeles). They expect of their finacial aid that the restauration process will be documented and published. The Getty Foundation, the World Monuments Fund and other local funds financed research and documentation in the case of Viipuri library by Alvar Aalto.[6] This library stood in Finland when it was finished in 1935, but after WW II the city becoming Russian was renamed Vyborg. This made the situation more complex. The remarkable international efforts, dating from 1992 saved finally this unique library in a cooperation of Finish architects and Russian firms (2013).

A fine glossary and impressive short biographies of the authors – who combine international experience and research – are included.  In general technical information on various window glass types and brands with explanations are a constant feauture of the publication.

In Fallingwater by Frank Lloyd Wright (1937) the architect develloped a long range of sophisticated window solutions of which the metal frames are painted in Cherokee Red. One finds corners that open outward with in-swing insect sreens. Just next to this glass panes insert simply the rough ashlar walls, neglecting all architectural traditions. A photo on p. 81 shows a window bar with two 90-corners in the horizontal plane, the glass panes glued together on the corners. As an overall problem the concrete slabs and balconies tended to deform by gravitation over time, and engineers had to solve this. Given the moisturous climate on the Mill Run Creek waterfall, exposed metal corrodes quickly. All this resulted in changing glass panes frequently, often in the course of painting the frames, and of in-kind repair of metal profiles. The costs for this rather successfull strategy were such that in 2009 the owner Western Penssylvania Conservancy started a Window Legacy Fund, stating to experts and the big public how important glazing is for the heritage. Only in small parts IGU was introduced to this monument, which ment a compromise regarding the urge to save the collection and furnishing kept in the interior.

The question of double glazing became a central theme for a new use of the Van Nelle Factory, designed by Brinkman & van der Vlugt with engineer Jan Gerko Wiebenga in 1931.[7] The multi-story reinforced concrete structure on mushroom pillars, for processing coffee, tea and tobacco, has a curtain wall structure at all facades. In this the lower third part was isolatied with Torfoleum (impregnated peat, now replaced), covered by silvery painted sheet metal. The reform for office spaces could be reached by installing interior walls (with IGU) on distance from the restorated curtan walls, thus shaping a corridor to the offices and a 80 cm zone on the north facade, mainly used for air conditioning.

A rather special chapter is on the Hallidie Building in San Francisco, 1918 by Willis Jeferson Polk.[8] Allthough  decorated with guilded historicist details the building was included to the book as being the first all-glass curtain wall in a metal frame. Behind this a normal concrete facade with big openings alows daylight introduction to the seven stories. Part of the restoration is the adding of metal consoles, in order to give support to every metal mullion, instead of every second, as before. The metal consoles as also the window frame are painted blue. The authors comment that the new ones could rather have been painted white, like the wall behind, in order to keep distinction between old and new, and enhance the alternating rhythm effects of before.

Chalenging restoration problems were due to the fate of Farnsworth house (1951) in Illinois by Mies van der Rohe, a weekend house for a single, Edith Farnsworth.[9] The completely glassed house, with fine steel and window details, and travertin floor, stands near Fox River. In order to avoid the risk of high water the house is lifted 1.6 m, making use of the same eight pillars, that carry the roof and hold the glass wall. But history showed that this was not enough. Several times dirty river water attacked the foot area of painted steel frames and the abundant glass fittings. Many glass panes were destroyed, among others by desoriented birds, and replaced in different kinds. Structural corrosion is a fundamental problem. The authors use also for this building the word “icon”. So, apart from the described technical performance, and the discussion whether Miss Farnsworth and other users felt comfortable during stays there[10], the house is also of highest “cultural importance” as the authors conclude following some sources. It is “temple-like” and represents Mies’ vision of Modern architecture as “almost nothing”, which stems from his ideal to reduce “every element to its essence”. This high rank results finally in current plans to lift the 140 m² area house with a technical appropriate machinery, during high rains. The owner of this museum house is the National Trust for Historic Preservation. A relocating of the house was a possible variant but this rather sensible solution for almost all problems  did not succeed, because of the landscape as part of the heritage.

In the Hardenberg House in Berlin by Paul Schwebes, (1956)[11] a pragmatic solution for the reglazing could be found. The long 7-story office building follows gently by two rounded corners the path of three conecting streets.  Original opening possibities and double one-pane glazing of the facade did not yet reach building physic standards. Yet that solution was hardly changed. Instead of this, at the rear facade, modern windows were installed, contributing to a reasonable overall performance. Fortuitously, the authors remark, new brass-colored blinds – instead of the original white – served to reduce the amount of sun reflection coming into the interior, resulting in less glare and overheating.

City of Refuge by Le Corbesier and Pierre Jeanneret in Paris (1933/1953)[12] may historically present a first class example how good intentions with a logical air-conditioning system got in troubles. The idea by the owner, the Salvation Army, was to give homeless a shelter, a place to sleep and to live, preventing them from inhaling the exterior air poluted with smoke. The intended system was not completely installed. Thus, almost directly the closed (!) curtain wall was opened with sliding windows for ventilation. In 1953 Le Corbusier himself planned a conventional facade with regular window frames in wood that could be opened and a certain sun protection by brise soleil, in the shape of simple concrete frames of protruding slabs. Finally the pragmatic restoration goal became “retaining the original use by reinforcing its adaptibility on contemporary requirements”. Still one found reasons to reconstruct some parts, like the penthouse facade with windows according to the first design.

Rather sceptic the authors  wrote the chapter on the De La Warr Pavilion, a 1933 competition result,  designed by Erich Mendelsohn and Serge Chermayeff, which was finished in 1935.[13] The building includes museum space and exterior balconies looking out to the Channel in Bexhill-on-Sea, UK. The impresive expression of Mendelsohn’s rounded staircases are important feautures. The care by the architects is shown by heating coils, following the structure of the glassed staircase. In the restoration these coils where saved but cut off from their heating function, allthough corrosion by salty air was, and is, a constant problem, also due to bad execution of the rounded windows. The architects tried to find good solutions for coating the exposed metal frame, but did not succeed. The authors ends with hopes for a better conservation plan.

A fundamental aspect of the book is that all details have been presented in perspective 3D drawings by rendered CAD. These where established with some care by various drawers and presented in page size. In this condensed way of documenting detail and material information the book saves space for many photos before and after the reglazing procedure. The depiction of details in 3D has its own history. Brillant Jean Prouvé (1901-1984) developed a design method which conceives details from the start in 3D. His colored perspective sketches provided all necessary information, especially for manufacturing.[14] Edward R. Ford was the first to deliver (redrawn) details of Modern Movement architecture on a statistic relevant scale and in a certain quality level.[15] In descriptive work on (recent) architecture standards are reached in Watts, Andrew, Modern construction handbook, Vienna 2013. This handbook serves with 3D colored images as well as 2D detail drawings in fine line.

But, the nice CAD drawings suggest perfect and logical solutions which are not always in line with reality. Persons who are involved with the reconstruction of details, know how tricky it is to interprete all dimensions, and the way hidden parts look like. As an example from the book one can observe that the figure on p. 163 in the chapter on Le Corbusier’s  La Tourette (1960)[16] is wrong. Depicted is a rectangle reinforced-concrete mullion in which single glass panes are held by putty in a wide ditch. The depicted detail revails to be erratic, since the narrower spans of the window type, does not allow the introduction of the pane in the slice, because of the restricted available dimensions, to move the panes. A closer look at photos show that the mullions have a T-shape, with a symmetrical stepped profile. On the interior the mullion element is thinner, thus alowing for the glass to find a clear position, defined by the step. This is relevant, since it is part of the problems – in this case clever simplicety – of LC Béton Brut architecture. Of course the detail also has sofisticated effects on the architectural expression, giving more slenderness to the mullions, alike a gothic profiled rib compared to a rectangle rib. In the book in general the problem of montage order of elements comes a bit short.

In a long Conclusions chapter the authors refine their initially stated three intervention levels‘ strategy. The case studies show that a mix of combinations is possible, with arguments pro and contra. In the future inventions like better insulated frames, insulating coatings, heated glass and thinner IGUs by vacuum will provide solutions, for problems which now seem unsolvable. In the mean time reconstruction of glass producing methods, stays a valid option.

Reglazing Modernism is a first class lesson for all who have to decide on Modern Movement heritage and who ask how they get a road map to meet with inherited complexities.

 

Book Review by Joseph Tomlow

 

More information:

Reglazing Modernism: Intervention Strategies for 20th-century Icons (English)
Birkhäuser Verlag, Basel 2019

Authors:
Angel Ayón, AIA, LEED AP
Uta Pottgiesser, PhD, Architect, Prof.
Nathaniel Richards, LEED AP

Hardcover: 256 Seiten
Verlag: Birkhauser Architecture (8. Oktober 2019)
English
ISBN-10: 3035618453
ISBN-13: 978-3035618457
22 x 30 cm

[1] Reglazing Modernism, p. 54.

[2] Reglazing Modernism, n.2, p. 21p. See also Short, C. Alan, The recovery of natural environments in architecture: air, comfort and climate. Routledge, Oxon GB, New York 2017 with comments on Modern Movement and air conditioning, p.42-62.

[3] Included case studies not mentioned in this text are: Glass House (P. Johnson, 1949), TWA Flight Center (E. Saarinen, 1962), Zeche Zollverein (F. Schupp, M. Kremmer, 1932/1961), Lever House (G. Bunshaft, SOM, 1952), S.R. Crown Hall (L. Mies van der Rohe, 1956), Fagus Factory (W. Gropius, A. Meyer, 1912/1925), Bauhaus Dessau (1926), Solomon R. Gugenheim Museum (F.L. Wright 1959), Yale University Art Gallery (L. Kahn1953).

[4] Sanatorium Zonnestraal in Hilversum NL, by Jan Duiker, Bernard Bijvoet and Jan Gerko Wiebenga is presented on p. 176-183. The founding of the international docomomo organization by Hubert-Jan Henket and Wessel de Jong, in 1988, was inspired by alarming questions raised during studies on the rather ruined pavilions of this sanatorium for TBC patients.

[5] Reglazing Modernism, p. 36-47.

[6] Reglazing Modernism, p. 64-71.

[7] Reglazing Modernism, p. 114-121.

[8] Reglazing Modernism, p. 56-63.

[9] Reglazing Modernism, p. 82-91.

[10] Miss Farnsworth kept mosquito nets surrounding the terrace, in spite of the archtect’s oppinion she should not do this. Initially Mies had planned them as the authors explain.

[11] Reglazing Modernism, p. 122-129.

[12] Reglazing Modernism, p. 184-195.

[13] Reglazing Modernism, p. 130-141

[14] Compare Peter Sulzer Jean Prouvé – Complete works Vol.1-4.

[15] Ford, Edward R. The Details of Modern Architecture 1,2, MIT London 1990/1996.

[16] Reglazing Modernism, p.158-165.