Susan Tunick
New York Landmarks Conservancy
Common Bond Vol. 10, No.1, April 1994
Clay, or terra-cotta, tiles are among the most ornamental and distinctive roofing materials used in historic buildings. Their aesthetic qualities, including a panoply of shapes, colors, patterns, and textures, often make tile roofs prominent stylistic features of many historic structures. Nowhere is this more apparent than in Alfred, New York, a rural town located in the Southern Tier of New York State, settled primarily by Seventh Day Baptists, that is filled with terra-cotta tile roofs. More that one hundred structures bear distinctive orange-red roofs, powerful reminders of a terra-cotta industry that thrived in Alfred between 1889 and 1909. Two companies, the Alfred Clay Company and the Celadon Terra Cotta Company (which evolved into the renowned Ludowici-Celadon Company in Ohio) transformed local high-quality raw materials into a wide variety of clay roofing tiles.
Typically, terra-cotta roofs comprise a field of plain clay tiles covering the majority of a roof’s flat surface, with decorative tiles used along the peak of the roof. In more ornamental installations, the field tiles may have areas of patterning created by tiles of different shapes, dimensions, or colors. Around Alfred, red tile roofs predominate, but there are many variations of clay colors, ranging from deep browns to pale pinks to buff or beige. By the end of the nineteenth century, as the use of glazed roofing tiles grew, blues, greens, and deep, nearly black, purples were popular colors.
Although clay tiles can last for centuries, the average life span of a terra-cotta tile roof is estimated to be about one hundred years. Many existing roofs in Alfred are approaching the end of their life spans. Community desire to preserve these roofs, and support from the Friends of Terra Cotta, generated a survey project that led to the publication of The Roofs of Alfred, which contains valuable information about the history, manufacture, repair, and preservation of tile roofs. The Friends of Terra Cotta is pleased to share some of this information with readers of Common Bond.
Historical Background
The word tile does not often occur in the Bible; but that tiles were used in very ancient times, not only in buildings, but also for many Purposes for which we employ paper, there is not the slightest doubt, and this is particularly true in regard to Assyria in which country almost every transaction of a public or private character was first written upon a thin tablet of clay, or tiles, and then baked.
judging from this introductory sentence on roof tiles in Charles Thomas Davis’ 1884 book, A Practical Treatise on the Manufacture of Bricks, Tiles, Terra-Cotta, Etc., it is clear that the history of roof tile is a long and venerable one. In North America, tiles were used by the earliest European settlers and were common in Spanish and French communities. Roof tiles have been found at the site of the 1585 settlement of Roanoke Island in North Carolina, as well as in other early English colonial towns. The Dutch also used clay tiles for roofs, importing them from Holland until 1650, when the local manufacture of clay tiles began in the upper Hudson River Valley.
The popularity of clay roof tiles continued during the Colonial period. By the 1770s, they were being produced in the East, particularly in the New York and New Jersey area, and in the West at the California Mission of San Antonio de Padua. The acceptance of clay tiles was based partially on their durability, ease of maintenance, and energy efficiency. Clay tiles were also fireproof, a quality that made them particularly attractive in the crowded, tightly-packed cities of the English colonies. The terrible fires in London (1666) and Boston (1679) led to the creation of building and fire codes in several Colonial cities, including New York and Boston, which encouraged the use of terra-cotta tiles for roofs because of their fireproof qualities.
Tile roofs are often prominent architectural elements of many historic buildings, as in Sacred Heart R.C. Church in Baton Rouge, Louisiana.
This tile roof uses raised, curved tiles, reminiscent of rhinoceros horns, to form diamond shapes. The darker, cross-shaped patterns are created by the insertion of dark brown tiles within the red field tiles.
Roofing tiles were made in a variety of shapes, as demonstrated in this illustration from A Practical Treatise on the Manufacture of Bricks, Tiles, Terra-Cotta, Etc. by Charles Thomas Davis.
T h i s a r t i c l e w a s p r e p a r e d b y S u s a n T u n i c k , t h e P r e s i d e n t o f t h e F r i e n d s o f T e r r a C o t t a , a n a t i o n a l p r e s e r v a t i o n o r g a n i z a t i o n , a s w e l l a s a n a r t i s t w o r k i n g i n c e r a m i c m o s a i c s .
J D u r i n g t h e l a t e - e i g h t e e n t h a n d e a r l y - n i n e t e e n t h c e n t u r i e s , c l a y t i l e s f a c e d s t i f f c o m p e t i t i o n f r o m o t h e r f i r e - r e s i s t a n t r o o f i n g m a t e r i a l s , i n c l u d i n g s l a t e , a n d m e t a l s s u c h a s c o p p e r , i r o n , z i n c , - a n d g a l v a n i z e d i r o n . C l a y t i l e s c o s t c o n s i d e r a b l y m o r e t h a n t h e s e m a t e r i a l s a n d w e r e a l s o m u c h h e a v i e r , r e q u i r i n g f a r m o r e s u b s t a n t i a l r o o f f r a m i n g a n d s h e a t h i n g . T h e i r f a l l f r o m f a v o r w a s t e m p o r a r y . T h e i n t r o d u c t i o n o f t h e I t a l i a n a t e V i l l a s t y l e o f a r c h i t e c t u r e ( w h i c h o f t e n f e a t u r e d a t i l e r o o f a s a n e s s e n t i a l s t y l i s t i c f e a t u r e ) i n t h e m i d - n i n e t e e n t h c e n t u r y s t i m u l a t e d a r e n e w e d i n t e r e s t i n t h i s m a t e r i a l . S w i n g s i n a r c h i t e c t u r a l t a s t e , r a t h e r t h a n f u n c t i o n a l i s s u e s , d i c t a t e d t h e e x t e n t t o w h i c h c l a y t i l e s w e r e u s e d u n t i l t h e e n d o f t h e c e n t u r y . T h e y r e g a i n e d p o p u l a r i t y , e s p e c i a l l y f o r r e l i g i o u s b u i l d i n g s , w i t h t h e a d v e n t o f t h e R o m a n e s q u e R e v i v a l s t y l e t h a t h a d b e e n i n s p i r e d b y t h e e a r l y m e d i e v a l b u i l d i n g s o f s o u t h e r n E u r o p e . O t h e r e c l e c t i c r e v i v a l s , s u c h a s t h e M i s s i o n , S p a n i s h B a r o q u e , G e o r g i a n , a n d M e d i t e r r a n e a n s t y l e s , w h i c h w e r e p o p u l a r f o r r e l i g i o u s b u i l d i n g s o f t h e p e r i o d , r e q u i r e d r o o f s c o v e r e d w i t h t e r r a - c o t t a t i l e s o f a l l t y p e s , s i z e s , c o l o r s , a n d t e x t u r e s , p r o m p t i n g t h e v o g u e o f c l a y - t i l e - c o v e r e d r o o f s t h a t l a s t e d w e l l i n t o t h i s c e n t u r y .
T h e M a n u f a c t u r e o f C l a y R o o f T i l e s
R e g i o n a l r o o f t i l e p l a n t s w e r e e s t a b l i s h e d i n a r e a s t h a t h a d e a s y a c c e s s t o l a r g e n a t u r a l d e p o s i t s o f c l a y . T h e m a n u f a c t u r e o f r o o f t i l e s w a s a f a i r l y s t a n d a r d i z e d e n t e r p r i s e . S h a l e , t h e p r i m a r y r a w m a t e r i a l u s e d , w a s b l a s t e d , d u g o u t b y h a n d , a n d t r a n s p o r t e d t o t h e t i l e p l a n t i n h o r s e - d r a w n w a g o n s . L a r g e c r u s h i n g m a c h i n e s p u l v e r i z e d t h e s h a l e a n d p l a c e d i t i n a p u g m i l l , w h e r e i t w a s m i x e d w i t h w a t e r t o f o r m a h o m o g e n e o u s m a s s o f c l a y . T h e c l a y w a s e x t r u d e d i n t o a w i d e s t r i p a n d c u t i n t o a s e r i e s o f c r u d e s l a b s c a l l e d " b l a n k s . " T h e s e b l a n k s w e r e t h e n p u t i n t o p r e s s i n g m a c h i n e s a n d f o r m e d i n t o r o o f t i l e s o f v a r i o u s s i z e s a n d s h a p e s . O n c e f o r m e d , t h e r a w t i l e s w e r e p l a c e d o n c a r t s , p u t t h r o u g h a d r y i n g t u n n e l , a n d t h e n l o a d e d i n t o t h e k i l n . T h e t i l e s w e r e b a k e d a t a t e m p e r a t u r e o f a b o u t 1 , 0 0 0 d e g r e e s F a h r e n h e i t , w h i c h p r o d u c e d t i l e s o f e x c e l l e n t c o l o r a n d s t r e n g t h .
B y t h e e a r l y t w e n t i e t h c e n t u r y t h e m a n u f a c t u r e o f c l a y r o o f t i l e s h a d b e c o m e a c o m p l e x , i n d u s t r i a l p r o c e s s . I n 1 9 0 8 , t h e C e l a d o n T e r r a C o t t a C o m p a n y o p e r a t e d e i g h t p r e s s e s . F i v e w e r e r u n b y p o w e r a n d t h e o t h e r t h r e e , u s e d f o r m o l d i n g s m a l l u n i t s , w e r e o p e r a t e d b y h a n d . T h e p r i n c i p a l p o w e r p r e s s e s w e r e s o e f f i c i e n t t h a t d a i l y p r o d u c t i o n i n c r e a s e d t e n f o l d o n c e t h e y w e r e p u t i n t o o p e r a t i o n . O r n a m e n t a l t i l e s w e r e e i t h e r m o l d e d b y h a n d , o r t h e t i l e p r e s s w a s a l t e r e d t o p r o d u c e a n e m b o s s e d d e s i g n . C o m p l e x u n i t s , s u c h a s h i p r o l l s , f i n i a l s , c r e s t i n g s , a n d o t h e r o r n a m e n t a l p i e c e s w e r e p r e s s e d b y h a n d i n t o p l a s t e r m o l d s . T h e s u r f a c e n e x t t o t h e p l a s t e r w a s t h e n s m o o t h e d b y h a n d s o t h a t i t w o u l d m a t c h t h e m a c h i n e - m a d e s u r f a c e o f t h e p l a i n t i l e . O c c a s i o n a l l y , o n e - o f - a - k i n d p i e c e s w e r e s c u l p t e d w i t h o u t u s i n g a m o l d .
T i l e r o o f s w e r e o f t e n c u s t o m - m a d e f o r s p e c i f i c b u i l d i n g s . A r c h i t e c t s w o u l d s u b m i t r o o f p l a n s t o t h e m a n u f a c t u r e r s p e c i f y i n g a p a r t i c u l a r s t y l e o f t i l e . C h a r l e s B i n n s , a r e n o w n e d p r o f e s s o r a t A l f r e d U n i v e r s i t y r e p o r t e d i n a n a r t i c l e t h a t a p p e a r e d i n T h e C l a y W o r k e r i n 1 9 0 4 t h a t t h e p l a n f o r " e v e r y h i p a n d v a l l e y i s l a i d o u t i n f u l l o n t h e f l o o r . E v e r y c u t t i l e i s m a r k e d a n d a p l a s t e r f o r m m a d e t o t h e e x a c t a n g l e r e q u i r e d , a n d t o t h i s t h e t i l e s t h e m s e l v e s a r e s h a p e d w h i l e g r e e n , a n d m a r k e d e a c h f o r i t s o w n p l a c e . " A t t h e C e l a d o n T e r r a C o t t a C o m p a n y , a f t e r f i r i n g , t h e r o o f t i l e s w e r e p a c k e d i n s t r a w , l o a d e d o n t o h o r s e - d r a w n w a g o n s , h a u l e d t o t h e A l f r e d s t a t i o n d e p o t , a n d s h i p p e d b y r a i l t o s i t e s a c r o s s t h e c o u n t r y .
P r e s e r v a t i o n o f H i s t o r i c T i l e R o o f s
C l a y r o o f t i l e s , w h e n c o r r e c t l y i n s t a l l e d , n e e d v i r t u a l l y n o m a i n t e n a n c e . I n f a c t , i t i s n o t u n u s u a l f o r c l a y t i l e s t o o u t l a s t t h e i r o r i g i n a l b u i l d i n g a n d b e r e u s e d o n a n o t h e r s t r u c t u r e . T o f o s t e r t h e p r e s e r v a t i o n o f a t e r r a - c o t t a t i l e r o o f , h o w e v e r , i t i s e s s e n t i a l t o l o o k a t t h e e n t i r e t i l e r o o f i n g s y s t e m . T h i s i n c l u d e s t h e m e t h o d b y w h i c h t h e t i l e s a r e f a s t e n e d , t h e s t r u c t u r a l r o o f i n g m e m b e r s , w o o d s h e a t h i n g , f e l t o r r o o f i n g p a p e r , a n d v e r t i c a l r o o f b a t t e n s t o w h i c h t h e t i l e s m a y b e a t t a c h e d .
C l a y t i l e s w e r e o f t e n u s e d o n b u i l d i n g s d e s i g n e d i n m a n y o f t h e e c l e c t i c a r c h i t e c t u r a l s t y l e s p o p u l a r d u r i n g t h e f i r s t h a l f o f t h e t w e n t i e t h c e n t u r y . S t . P a t r i c k ‘ s R . C . C h u r c h , a b o v e , i n S o u t h o l d , N e w Y o r k - , i s a S p a n i s h M i s s i o n e x a m p l e . B e l o w , S t . L e o t h e G r e a t R . C . C h u r c h i n N e w O r l e a n s , L o u i s i a n a , w a s e x e c u t e d i n t h e S p a n i s h B a r o q u e i d i o m .
A w a g o n l o a d e d w i t h o f r o o f t i l e s p a c k e d i n s t r a w p a s s e s t h e C e l a d o n T e r r a C o o t a
C o m p a n y o f f i c e b u i l d i n g i n A l f r e d , N e w Y o r k , o n i t s w a y t o t h e r a i l d e p o t i n t h e l a t e 1 8 0 0 s .
H i s t o r i c a l l y , w h e n a c l a y - t i l e r o o f w a s i n s t a l l e d , t h e r o o f s h e a t h i n g w a s f i r s t c o v e r e d w i t h a n a s p h a l t - s a t u r a t e d f e l t p a p e r o f b e t w e e n f o r t y - f i v e a n d s i x t y - f i v e p o u n d s d e p e n d i n g u p o n t h e s t y l e o f t i l e . O v e r t h i s , t h e t i l e s w e r e a t t a c h e d w i t h a s p e c i a l t w o - a n d - a - h a l f - i n c h m e t a l a l l o y n a i l t h a t r e s e m b l e s p r e s e n t - d a y g a l v a n i z e d e i g h t - p e n n y n a i l s . E a c h n a i l w a s h a m m e r e d s o t h e h e a d o f t h e n a i l r e m a i n e d a q u a r t e r o f a n i n c h a b o v e t h e t i l e , t h e r e b y a l l o w i n g f o r t h e e x p a n s i o n a n d c o n t r a c t i o n o f e a c h t i l e w i t h i n t h e r o o f s y s t e m . C o p p e r s h e e t s w e i g h i n g f o u r t e e n o u n c e s p e r s q u a r e f o o t w e r e u s u a l l y s p e c i f i e d f o r c h i m n e y a n d v a l l e y f l a s h i n g . R a i n g u t t e r s a n d d o w n s p o u t s w e r e o f t e n m a d e o f t h e s a m e m a t e r i a l . A f t e r a l l t h e t i l e s w e r e i n p o s i t i o n , m o r t a r w a s u s e d t o s e a l t h e r i d g e a n d h i p t i l e s . T h i s p r o c e s s p r o t e c t e d t h e r o o f f r o m h a r s h w e a t h e r c o n d i t i o n s a n d k e p t b i r d s f r o m n e s t i n g i n t h e n a t u r a l v o i d s c r e a t e d b y t h e t i l e s .
T h e m o s t c o m m o n f a i l u r e i n a t i l e r o o f i s c a u s e d b y a b r e a k d o w n i n t h e f a s t e n i n g s y s t e m , w h i c h f r e q u e n t l y c o n s i s t s o f i r o n n a i l s , a l t h o u g h i n s o m e r o o f s w i r e a n d w o o d e n p e g s w e r e u s e d . A s e c o n d c o m m o n f a i l u r e i s t h e s u p p o r t s y s t e m , w h i c h m u s t b e s t r o n g e n o u g h t o b e a r t h e l o a d o f a h e a v y t i l e r o o f . I f m e t a l f l a s h i n g , g u t t e r s , a n d d o w n s p o u t s d e t e r i o r a t e o r a r e f i l l e d w i t h d e b r i s , w a t e r w i l l n o t r u n o f f t h e r o o f p r o p e r l y a n d c a n s e e p u n d e r r o o f t i l e s , d a m a g i n g t h e s u p p o r t i n g m e m b e r s . T i l e r o o f s c a n a l s o b e h a r m e d b y o t h e r f a c t o r s , i n c l u d i n g f a l l i n g t r e e l i m b s , h e a v y h a i l , a c t s o f v a n d a l i s m , o r b y c a r e l e s s r o o f e r s w a l k i n g o n u n p r o t e c t e d t i l e s w h i l e e x e c u t i n g r e p a i r s .
P r o p e r l y a s s e s s i n g t h e c o n d i t i o n o f a h i s t o r i c t e r r a - c o t t a t i l e r o o f i s a j o b f o r a p r o f e s s i o n a l . H o w e v e r , v i s u a l i n s p e c t i o n b y t h e b u i l d i n g o w n e r i s a v a l u a b l e p r e l i m i n a r y s t e p . P a y a t t e n t i o n t o m i s s i n g a n d d a m a g e d t i l e s , a s w e l l a s t o s i g n s o f w a t e r d a m a g e o n t h e i n t e r i o r . A l t h o u g h i t m a y b e o b v i o u s t h a t t h e r o o f i s l e a k i n g , t h e s o u r c e o f t h e l e a k c a n p r o v e d i f f i c u l t t o f i n d b e c a u s e t h e w a t e r c a n f l o w o v e r a n d a r o u n d o t h e r b u i l d i n g e l e m e n t s a n d n o t b e c o m e v i s i b l e u n t i l i t h a s t r a v e l e d f a r f r o m i t s s o u r c e . W h e n t h e c a u s e o f t h e l e a k h a s b e e n i d e n t i f i e d , a n d a p l a n f o r r e p a i r h a s b e e n d e v e l o p e d , k e e p i n m i n d t h e i n h e r e n t f r a g i l i t y o f r o o f i n g t i l e s . A l t h o u g h s o m e t i l e s c a n b e w a l k e d o n i f a d e q u a t e p r o t e c t i o n i s i n p l a c e , i t m a y b e t i l e i n o r d e r t o p r o v i d e a s a f e w a y t o r e a c h n e c e s s a r y t o r e m o v e w h o l e a r e a s o f t i l e s e c t i o n s i n n e e d o f r e p a i r . W h e n a n a r e a o f t i l e s i s r e m o v e d , c a r e s h o u l d b e t a k e n t o m a k e a d i a g r a m a n d c r e a t e a t i l e n u m b e r i n g s y s t e m t h a t c a n b e u s e d t o r e p l i c a t e t h e o r i g i n a l p a t t e r n a n d c o l o r v a r i a t i o n s w h e n t h e t i l e s a r e r e l a i d .
T h e a p p e a r a n c e o f h i s t o r i c t i l e s c a n b e h a r d t o m a t c h , r e q u i r i n g i n g e n u i t y i n r e p l a c i n g m i s s i n g t i l e s w i t h o t h e r s t h a t a r e h a r m o n i o u s i n c o l o r a n d t e x t u r e . I t m a y b e a p p r o p r i a t e t o m o v e o r i g i n a l t i l e s t o t h e m o s t c o n s p i c u o u s a r e a s o n t h e r o o f a n d t o u s e n e w l y m a d e o r s a l v a g e d t i l e s i n l e s s p r o m i n e n t p l a c e s . M a n y t i l e s a r e m a r k e d o n t h e b a c k w i t h t h e n a m e o f t h e m a n u f a c t u r e r a n d a n u m b e r f o r t h e p a r t i c u l a r t y p e o f t i l e . S o m e c o m p a n i e s s t i l l i n o p e r a t i o n c a n o f t e n r e p r o d u c e s p e c i f i c t i l e s , s o m e t i m e s e v e n u s i n g t h e o r i g i n a l . m o l d s . W h e n r e a t t a c h i n g t i l e s , n e w c o r r o s i o n - r e s i s t a n c e r e s i s t a n t f a s t e n e r s s h o u l d b e u s e d .
T h e m o s t i m p o r t a n t e r r o r t o a v o i d i n r e p a i r i n g a n h i s t o r i c t i l e r o o f i s t h e r e p l a c e m e n t o f t i l e s w i t h a n o t h e r m a t e r i a l . C o n c r e t e , m e t a l , o r p l a s t i c t i l e s a r e n o t s u i t a b l e s u b s t i t u t e s f o r c l a y r o o f t i l e s . T h e y d o n o t h a v e t h e s a m e t e x t u r e , s h a p e , t h i c k n e s s , o r s u r f a c e a n d c o l o r v a r i a t i o n s f o u n d i n n a t u r a l c l a y t i l e . A n o t h e r p i t f a l l t o a v o i d , w h i c h c a n l e a d t o f u r t h e r d e t e r i o r a t i o n , i s t h e p a t c h i n g o f a h i s t o r i c t i l e r o o f w i t h i n a p p r o p r i a t e m a t e r i a l s s u c h a s t a r , c a u l k , a s p h a l t , o r s e c t i o n s o f m e t a l .
T e r r a - c o t t a t i l e r o o f s a r e s t y l i s t i c a l l y a n d f u n c t i o n a l l y v e r y i m p o r t a n t f e a t u r e s o f m a n y h i s t o r i c b u i l d i n g s . I n t o d a y ‘ s w o r l d w h e r e a r c h i t e c t u r a l c o n f o r m i t y i s t h e r u l e , t h e d i s t i n c t i v e a e s t h e t i c q u a l i t i e s t h a t t e r r a - c o t t a t i l e r o o f s a d d t o a b u i l d i n g a r e t o o o f t e n u n a p p r e c i a t e d . W i t h a p p r o p r i a t e m a i n t e n a n c e , t h e s e d u r a b l e a n d a e s t h e t i c a l l y a p p e a l i n g r o o f s w i l l o u t l a s t t h e b u i l d i n g o n w h i c h t h e y w e r e i n s t a l l e d .
A c l a y t i l e r o o f b e i n g r e p a i r e d . I n t h i s e x a m p l e , t i l e s s a l v a g e d f r o m l e s s v i s i b l e a r e a s a r e b e i n g r e i n s t a l l e d o n t h e P r i m a r y r o o f o v e r t h e n a v e o f S t . M a r y ‘ s R . C . C h u r c h i n O s w e g o , N e w Y o r k .
S u s a n T u n i c k , t h e P r e s i d e n t o f t h e F r i e n d s o f T e r r a C o t t a , a n a t i o n a l p r e s e r v a t i o n o r g a n i z a t i o n , a s w e l l a s a n a r t i s t w o r k i n g i n c e r a m i c m o s a i c s , p r e p a r e d t h i s a r t i c l e t e r r a c o t t a t i l e r o o f s . M o r e t h a n c o m p a n i e s e n o c c u r i n t h e B i b l e ; b u t p o s e s f o r w h i c h w e e m p l o y p a p e r . T c l a y , o r t i l e s , a n d t h e n b a k e d t e r r a - c o t t a t i g h t l y p a c k e d i n t r o d u c t i o n o f t h e I t a l i a n a t e V i l l a s t y l e s C o m p l e x u n i t s , s u c h a s h i p r o l l c r e s t i n g L o u i s i a n a e r r a C o t o t h e r f a c t o r s , i n c l u d i n g f a l l e n r e l a y e d ; m e t i m e s e v e n u s i n g t h e o r i g i n a l r e s i s t a n t f a s t e n e r s