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The Plan of St. Gall

a study of the architecture & economy of & life in a paradigmatic Carolingian monastery
  
  
  
  
  
  
  
  
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ROOF COVERING
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ROOF COVERING

The customary material used for covering the roofs of
Carolingian churches was tile or lead. The distinction is
not always clear, as the term tegula (classical Latin for
"ceramic tile") is used for both. However, it is probably
safe to assume that when tegula is used without the qualifying
adjective plumbea, it stands for tile.

When Benedict of Aniane founded his first monastery at
the banks of the stream of that name, he covered the
building "not with red-gleaming tiles, but with thatch"
(non tegulis rubentibus, sed stramine).[184] Conversely, when he
rebuilt the monastery in 772, "he covered the houses not
with thatch, but with tiles" (non iam stramine domos, sed


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Page 177
[ILLUSTRATION]

123. PLAN OF ST. GALL

CRYPT OF THE CHURCH

AUTHORS' INTERPRETATION

Whatever the precise shape of the space designated
CONFESSIO it obviously could not have exceeded an area
confined to the north and south by masonry of the
Presbytery walls and to the west and east by walls separating

CONFESSIO from crossing and from the transverse arm of the
corridor crypt. It is also clear that the Crypt's two
longitudinal arms would have come to lie outside the masonry
of the Presbytery walls. To clear these walls they would
each, in construction, be moved outward by 2
½ feet; but the
builder could have easily complied with this need, since the
Crypt arms were underground and the space invaded by their
outward displacement would not have diminished any
adjacent structure. The
CONFESSIO surely must have been
covered with groin vaults because of the weight of the
superincumbent Presbytery floor with its high altar and
heavy loading from constant use.

In the plan shown to the right Ernest Born has subdivided the 40-foot
squares of crossing and Presbytery internally each into sixteen 10-foot
squares and the latter again
(in the areas occupied by the crypt) each into
sixteen 2½-foot squares. Our reconstruction shows how easily and
convincingly the masonry of an actual building can be developed within the
framework of the grid that forms the conceptual basis of the Plan — masonry
and foundation solid enough to carry the load of the superincumbent walls
of the Church.

The CONFESSIO is here interpreted as an inner hall crypt of roughly 20 by
30 feet with a ceiling formed by six groin vaults each covering the surface
area of a 10-foot square
(100 square feet).

In the interpretation illustrated here the gray tint indicates walls of the church above
in locations depicted on the original document, and the U-shaped crypt passage or
corridor is presumed to be covered with a barrel vault.

tegulis cooperuit).[185] From chapter 26 of the capitulary
issued by Charlemagne at the synod of Frankfurt in 794,
it appears that tile was then the customary cover for
church roofs.[186] But before the century had come to a close,
lead appears to have moved into the foreground. It was
with tegulis plumbeis that Charlemagne covered the Palace
Chapel at Aachen (consecrated in 805).[187] The same material
was used by Abbot Ansegis (807-833) to cover the church
of St. Peter's at St. Wandrille,[188] by Bishop Hincmar (845882)
to cover the roof of the cathedral of Reims,[189] and by
Einhard to cover the roof of his church of SS. Peter and
Marcellinus, at Seligenstadt (started in 827). The purchase
of lead for the latter and the difficulties encountered in

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procuring it are discussed in an undated letter of Einhard's
written to an unidentified abbot:

I am speaking about the conversation we had when, meeting in the
Palace, we talked about the roof of the blessed martyrs of Christ.
Marcellinus and Peter, which I am now trying to build, although
with great difficulty, and a purchase of lead for the price of 50
pounds was agreed between us. But although work at the basilica
has not yet reached the point where I should be concerned with the
necessity of building the roof, yet it always seems that we should
hasten, because of the uncertain span of mortal life, to complete the
good work we have begun, with God's help.[190]

 
[184]

Schlosser, 1896, 183, No. 573.

[185]

Ibid., 184, No. 574.

[186]

Ibid., 11, No. 41; and Mon. Germ. Hist., Leg. II, Cap. I, ed. Alfred
Boretius, 1883, 76, chap. 26: "Lignamen, et petras sive tegulas, qui in
domus ecclesiarum fuerint.
"

[187]

Schlosser, 1896, 29, No. 112.

[188]

Ibid., 290, No. 870: "Ipsam namque turrim simulque obsidem tegulis
plumbeis a novo cooperiri iussit.
"

[189]

Ibid., 250, No. 771: "Terti templi plumbeis cooperuit tabulis."

[190]

Einhardi omnia opera; ed. Teulet, II, 1843, 82-85. After this paragraph
was written, Bernard Bachrach brought to my attention an article
by Hans van Werveke on the commerce of lead in the Middle Ages,
where reference to other lead-covered churches may be found. See van
Werveke, 1926.