Improvements in the Construction of Roofs.
Year: 1891

page_text: Date of Application. 21st Oct., 1891
Complete Specification Left, 20th July, 1892-Accepted, 20th Aug., 1.92
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Roofs.
I, AUGUST FÖPPL of Leipzig, Saxony in the Empire of Germany, Engineer do
hereby declare the nature of my said invention to be as follows :-—
The object of my invention is to effect improvements in the construction of roofs,
and my invention consists in the application of trellis work in the construction of
roofs, whereby the ordinary tie beams, king and queen posts, and struts, are entirely
dispensed with.
In forming roofs for rectangular buildings, I place a number of purlins, of
sufficient scantling for the length of the roof, and rest the ends of these purlins
upon opposite walls of the building usually the gable ends, in a curved line trans-
versely to the purlins, such curved line preferably approximating to a segment of
a circle. Transversely to these purlins and following the segmental curve, I place
a suitable number of rafters. The purlins and rafters are further supported and
secured by means of diagonal rafters crossing each other. These diagonals may
however be dispensed with in the spaces between the lowest purlins and the walls,
when the roof has a considerable rise.
My invention is applicable to roofs of large as well as small spans, and the
proportions of the purlins, rafters, diagonals, and other details may be very much
varied to suit the dimensions and curves of the roofs.
Dated 21st October 1891
GEO.
DOWNING,
8, Quality Court, London, W.C., Agent.
COMPLETE SPECIFICATION.
Improvements in the Construction of Roofs.
I, AUGUST FÖPPL, of Leipzig, Saxony, in the Empire of Germany, Engineer, do
hereby declare the nature of my said invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:
The object of my invention is to effect improvements in the construction of
roofs.
My invention consists in the application of trellis work to the construction of
roofs, whereby the ordinary tie beams, king and queen posts and struts are entirely
dispensed with.
In forming roofs for rectangular buildings, I place a number of purlins, of sufficient
Scantling for the length of the roof, and rest the ends of these purlins upon opposite
walls of the building, in a curved line transversely to the purlins; such curve
preferably approximating to a segment of a circle, or a parabola. Transversely to
these purlins, and following the segmental or other curve, I place a suitable number
of rafters. The purlins and rafters are further supported and secured by means of
diagonal rafters crossing each other. These diagonals may however be dispensed
with in the spaces between the lowest purlins and the walls, when the roof has a
considerable rise.
My invention is applicable to roofs of large as well as small spans, and the propor-
tions of the purlins, rafters, diagonals, and other details, may be very much varied
to suit the dimensions and curves of the roofs.
And in order that my said invention may be particularly described and ascertained,

page_text: reference is hereby made to the accompanying drawings, in which similar letters of
reference indicate corresponding parts.
Fig. 1 is a sectional elevation, Fig. 2 a side view, and Fig. 3 a plan; illustrating
the simplest form of trellis construction.
Fig. 4 is a sectional elevation, illustrating a combination form of trellis
construction.
a a are the gable walls of the buildings. bb are the side walls. cc are purlins,
the ends of each purlin resting upon the gable walls, or upon wall plates attached
to the gable walls, for supporting the purlins. One end of each purlin is made
fast to its support, and the other end is so supported as to leave it free to expand
and contract with the variations of temperature. d d are rafters fixed to the
purlins at equal distances apart, and e e are intermediate rafters placed diagonally
to the purlins, and meeting the junctions of the purlins with the rafters d d; the
rafters e e crossing each other, as shown in Figs. 1, 2 and 3.
In Fig. 4 a further development of the trellis construction is illustrated, for
larger spans requiring greater strength and rigidity. In this case the trellis work
system is duplicated, as herein before described, and so arranged on the cylindrical,
or other structural form as aforesaid, that the purlins c and alternate in position
and connection with their respective rafters. In like manner the diagonal rafters
are carried over and under each other to alternate purlins; the whole being firmly
connected together and forming a rigid structure for supporting any ordinary kind
of material usually applied to roofs.
The diagonal rafters may be dispensed with in the spaces next to the side
walls, from to g, as the roof is sufficiently rigid without diagonal rafters in such
spaces.
I sometimes apply lattice work or net work to the rectangular spaces, instead
of using diagonal rafters, whereby the aforesaid principle of construction may be
in like manner carried out; the principal strains of the roof being transmitted to
the gable walls a a.
Having now particularly described and ascertained the nature of my said inveu-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In the construction of roofs, the combination of horizontal purlins c, arranged
in a cylindrical, polygonal, or approximate form, extending from one gable wall
to the other, and intermediate rafters d and e, connecting such purlins, 80 as to
form a rigid roof support, substantially as herein before described and illustrated
by Figs. 1, 2 and 3 of the drawings.
C
2. In the construction of roofs as aforesaid, the combination of two or more
systems of trellis work, the purlins c and c¹ being arranged in alternate positions
and secured to their respective rafters, together forming a segmental, polygonal,
parabolic, or other analogous structural form of support, substantially as herein
before described and illustrated by Fig. 4 of the drawings.
3. The general construction, arrangement and combination of the several and
respective parts, together forming my invention of improvements in the construc-
tion of roofs, substantially as herein before described and illustrated by the
drawings.
Dated 20th July 1892.
GEO.
DOWNING,
8, Quality Court, London, W.C., Agent.