IMPROVED ROOFS
Year: 1884

page_text: I DAVID GRIFFITHS, of Chester Road, Erdington, Near Birmingham, in the
County of Warwick Gentleman do hereby declare the nature of the said Invention
for IMPROVED ROOFS.
Roofs are at present constructed high in pitch & gable, as the only means
hitherto used for keeping out wind and water. But the greater the elevation,
the greater the force of foul weather on slates, tiles, & bricks. Chimnies, to draw
properly, must be considerably higher than the apex of the roof & gables In all
this there is great waste of material & labour; yet efficiency is not attained. To
obviate over-pressure on the walls the whole structure of the roof is slender, often
shakey; the slates & tiles are thin & fragile; leakage, breakage, & frequent repairs
are chronic faults in roofs as at present constructed; and in storms of wind slates,
tiles & bricks fly from their seats & chimnies crash down with very serious, often
fatal, results,
I propose to do away with the above structural defects & their evil results, by
substituting a roof quite proof against wind, rain, & snow, even in stormy weather;
strong, sound, durable, & seldom out of repair; and a considerable saving both in
materials & labour. Attics & garrets will disappear, the uppermost rooms being as
regular & as well-lighted as those below.
Now according to my invention the Roof is nearly flat with only pitch enough
to facilitate the economical cutting of the supports, & to cause water to run off
quickly into the gutters, & thence into the perpendicular pipes. There is no
horizontal spouting used; consequently no eaves-dropping or spout-overflowing can
possibly occur. No rafters are used. The supports are of wood--but can be made
of iron. When of wood the piece or pieces, as the difference of span may require,
are cut, to economize material, in such a way as to transfer wood from the two
ends where less strength is needed, to the middle where greater bearing power is
essential. These supports, thus prepared, are laid on the walls like the joists which
support room floors, having a bearing at each end only. Laths are used as here-
tofore, but placed closer to each other, so as to carry a bed of morter, cement, or
other concrete in which to lay the tiles. The staple tiles are made of clay, but of
a new pattern manufactured solely for this invention. Likewise the crest or ridge.
tile. Also the gutter-tile, & it to a great extent, supercedes the use of lead & other
costly materials. Instead of burnt-clay tiles wood, iron, lead, zink, glass, slate, or
stone may be the materials used, partly or entirely. A little elevation of the wall
above the roof prevents the sliding down of dangerous avalanches of snow. A small
trap-door in the ceiling of the top room, opened opportunely will soon melt away
any accumulation of snow.

page_text: I DAVID GRIFFITHS of Chester Road, Erdington, near Birmingham, in the
County of Warwick, Gentleman do hereby declare the nature of my invention
for IMPROVED ROOFS and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
My invention is designed to produce a roof that shall be strong and sound,
impervious to wind and water even when rain is driven by a gale-also durable
and seldom requiring repairs. I do away with the bearing aid of gable walls and
high pitch together with elaborate construction. also abolish purlins, tile rafters,
ceiling joists, wall plating, and ridge boards. My roof is well-nigh a flat surface or
terrace generally the ridge not above 18 inches higher than the gutter-Can be
used to walk on, also to sustain flower pots. Where this roof is used the chimnies
can be built less tall by several feet-several yards in some cases-each, thus
obviating the danger of falling during high winds. I use gutter-tiles inside the
four walls, but no horizontal spouting outside, consequently eaves-dropping, spout-
overflowing, and avalanches of thawing snow cannot occur The outside walls
being all built up to one height, a little (say 18 or 24 inches) above the gutters,
will provide scope for ornamenting the tops of buildings, prevent the roof's being
seen from below, and deprive wind, even a huricane, of its hitherto undisputed
claim to be the chief factor taken into account in constructing a weather-proof
roof. A distinguishing feature of this roof is that the inner-not less than outer-
walls are utilized in supporting the weight. My invention does away with attics
and garrets, with their every-shaped and no-shaped ceilings; the rooms immediately
under the roof being as entirely rectangular as those on the under stories. My roof
being quite sound and tight, will in winter have, naturally have, an under-warmth
capable of promptly thawing away the heaviest falls of snow, even when accom-
panied by frost. But I provide for an increase of snow-melting heat if necessary,
by a simple contrivance that can be used or not at will. My invention achievs a
saving in both materials and labour, also prevents that waste of covered space
which is inseparable from high-pitched roofs. No piece of wood in my roof can
cause damage by setting fire to the fabric, as none is so placed as to be in riskey
contiguity with the inside or any side of any chimney. Granted good workmanship
in my roof, no wall-damp, occasioned by roof-leakage can occur. Given fair work-
manship, no force of driving rain or snow can penetrate any spot of this roof.
Now according to my invention its chief features appear in its Principals, Tiles,
and Laths. In the accompanying 10 sheets of drawings similar letters denote
corresponding parts wherever they occur.
:
I PRINCIPALS SEE SHEET OF DRAWINGS L
Fig 1. A plain plank of, say 12 feet long 1 foot wide and 3 inches thick―(in
practice differing in length and strength as width of span and amount of upper
weight may require) Rip at each end on line drawn from widdle of width up to
one fourth of length. a a. Turn the severed pieces upon the middle of what was
the plank and it forms;-Fig 2, The Principal, making it say 12 feet long 1 foot
6 inches high in the middle a a, each side tapering down to 6 inches high at its
end bb. The constituent parts are fastened together by bolts or other means.
These principals are placed so that each end takes its bearing on a wall-just as do

page_text: the two ends of room-floor joists. The number of principals used with their length
and strength, also their distance apart will vary in different cases, according to
circumstances. No rafters are used, not being needed, as the tiling laths are nailed
on the upper edge of the principal; nor are cieling joists used as the ceiling laths
are nailed on principal's lower edge.
Fig 3. In some cases the two upper pieces may be formed from a seperate half
plank, A sawn according to line bb, and fixed on the main plank B. Fig 4. To
secure adequate bearing strength at and near the centre of the principal is obviously
a crucial point, on which I remark:-First-The principal's centre has three times
the bulk of each extremity, therefor three times the supporting power-if rendered
as solid and strong as un-cut wood of the same dimensions. Secondly. The upper
edge of the principal tapers down from centre to extremities, thus distributing the
whole weight equally along the entire width from wall to wall, thereby producing
an amount of elasticity from end to end of the principal, considerably to the relief
of its centre. Thirdly-The roof's being well-nigh flat, instead of highly pitched,
reduces the weight of tiles, morter, and laths, by at least one third, and that when
considering only the smaller space to be covered. Fourthly-My tiles, being not
doubled, except at the lappings of the ridge-tile, will reduce the tile-thickness of
the entire roof about one third as compared with common tiles. Fifthly-Ridge
tiles hitherto used are of necessity very heavy, which must be taken into account,
as the ridge presses on the centre, which is the point most of all needing to be
strengthened, whereas my ridge-tile can be made very light, yet efficient, because
the projection downwards from the centre of its under surface renders it immovable.
Sixthly My principals will generally have to carry over comparatively narrow
spans, because they can take their bearings on the interior walls, as well as on the
four, or more, outside walls. See Sheet III Fig 4. The whole width of house is
covered by a of itself, by b and c together, by e and f together, or by def together.
But these principals can be made to bear efficiently over the wider spans without
support from interior walls-Assembly Rooms, for example-by the aid of sub-
pillars or other sub supports.
Nevertheless, I contribute further strength to principal's centre :-First, by two
plates one on each side, and bolted to the wood and to each other by the same
bolts a. Second, a pair of straps, extending laterally from each side of the plate, and
bolted, bb. Third, a brace all round centre of principal, constituted by two clips,
one round upper edge of wood, the other round under edge of wood c c and these
drawn towards each other by a screw-pin and button, or bolt, on each side.
Fourth, a few herring-bone or plain board struts will be placed between the
principals Fifth, a flat bar of charcoal iron or sheer steel, thickest in its middle,
of width to fit under-edge of principle, to extend some distance from centre of
principle towards each end, fastened on under edge of principle by bolts driven in
or screwed in. Sixth, two strips of wood, strongest in middle, nailed or bolted, one
on each lower side of the centre of the principle, and extending a suitable distance
laterally towards each end of the principal. Seventh, two thin planks, one on each
side of the principal at its centre to fit its whole depth, extending laterally to a
suitable distance, bolted to principal and to each other by the same bolts. Fig 5.
A plank and a half plank the latter cut into two equal parts a a, and fitted to stand
on the former bb, with trusses between them or trusses and a king post cc c, and
plates, straps, brace, flatbar, two strips of wood and two thin planks or one of
these strengtheners only, or as many more as required, and varied in pattern if.
thought desirable. But this arrangment with other contrivances that I may see
fit to use to strengthen the principal's centre, must of course be made to accord
with the chief feature of my invention, namely, a roof as nearly flat as possible.
The above mentioned plates, straps, and brace are made of iron or steel, cast or
wrought. The principles are of wood, but may be of angle-iron or angle-steel.
The principal shewn in Fig 5, is designed to meet cases which may require different
arrangments and to have more component parts in their construction.

page_text: II. TILES. SEE SHEET II.
Fig 1. This tile comprises male and female, interlocking at the sides by plough-
grooves, the grooves being in the upper side of the female and under side of the
male. These tiles overlap at the lower ends and underlap at the upper ends, by
somewhat deep bevel-angles. Surface of roof of these tiles is quite level; I mean
quite free from the lateral lines of steps necessarily made when tiles are laid on
double, also quite free from any other impediment to the running off of water.
Fig 2. This tile interlocks at each of its four sides of contact with its fellow tiles by
a plow-groove. The grooves on its right side and lower end are in its under
surface, those on left side and upper end, in its upper surface. Surface of roof quite
level. Fig 3. This tile has rebate joints. The rebate on its right side and lower
end is in its under side, that on left side and upper end in its upper side. Whole
surface of roof level. Fig 4. This tile at each of its four edges joins its fellow tiles
by a somewhat deep bevel angle. The angles on its right side and lower end are
on its under side, those on left side and upper end on its upper side. Whole surface
of roof level. Fig 5. This tile is rectangular like a common paving brick, except
that its upper right side and lower end are rebated by the laying on of a small rib.
On the finished roof made of these tiles the surface is not quite level. The lines of
rib will run laterally from wall to wall, also downwards from ridge to gutter. The
latter ribs will accelerate the running off of water by deviding it into seperate
currents, and further to accelerate the flowing the tile may be a little hollowed out
in the middle. The former ribs having their edges bevelled will not allow water to
lodge or retard its downward flow.
I use a sixth shape of tile, namely a rectangular one, to lie simply flat in morter,
-like pavement bricks-This will be understood. The shape of this tile is com-
monly used on pavements, kitchen floors, &c. but its use as the staple tile of a roof
is novel. To secure the exact fitting and sound adhesion of the course of tiles next
the ridge on each side I mould and bake top-course-tiles of one half one quarter or
three quarters less depth than the ordinary size tiles. These tiles of deminished
depth have their upper edge of full thickness, so as to fit the downward projection
from the under surface of the ridge-tile, see Sheet III Fig. 1. c. I also make
staple tiles of full size, to go next the wall at each end of the roof. These have a
wall-contact edge of the full thickness of the tile.
I shall mould all or any of the staple tiles, (should practice recommend this) to
have on the upper surface and over the joints a rib running from ridge to gutter.
This will strengthen the tiles at the part where the joint weakens them, break the
force of the perpendicular fall of heavy rains, accelerate the down-running of
water by narrowing and deepening its currents-thereby diminishing appreciably
the weight of heavy and sudden falls.
I make these tiles of burnt clay of the most adhesive and least pourous kind.
Common tiles and even may possibly be used by much and careful adaptation, also
galvanized sheet iron or galvanized corrugated iron, and sheet or corrugated zinc,
can in some cases and by careful adaptation be used as the covering of my roof, and
used so as consistently to fall in with its principle and escential features.
I use best lime morter, or other suitable material, more or less as required by the
different tiles and either point, or face, or wash down with Portland or other
cement according to need in different cases.

page_text: last course of the staple tiles 13 similar to that of ordinary ridge-tiles, except that
its angle is extreemly obtuse, d d, to correspond with the roof's angle.
Fig. 2. Gutter-tile. It is moulded and burnt all in one piece. The perpendicular
side a, is placed against the wall. The next or horizontal part b b, is the bottom of
the gutter. The third part o c, rises at an angle corresponding with the roof, and
is really in its use the lowest course of the staple tiles. At one end of the gutter-
tile on its upper side is a rebate d d,-it can be made a plough, groove or a bevel
angle at the other end e e, is a corresponding rebate, or groove or bevel on its
under side-The edge of this tile f, shews a rebate but the jointing will be made
to vary so as to correspond with the jointing of the particular tiles used. In some
cases the channel formed by the gutter-tiles can be constituted of sheet lead, or
iron, cast or wrought.
Fig. 3. Gutter-tile-double. This is used when it is convenient or necessary that
the water should run into one and the same channel off two sides of a roof, said
sides being so situated that the water of each will naturally flow down and mingle
with that of the other. When laid, the middle part of this tile a a, is of course
horizontal, its two sides rising at the same angle as the roof, and doing service as
the lowest course of staple tiles. Along one end of the gutter-tile-double b. b, is a
rebate on the under side-it can be a plough groove, or a bevel angle,-along the
other end c c, is a corresponding rebate, or groove, or bevel on the upper side. The
two edges of this tile dd, shew a rebate but the jointing will be made to vary so as
to correspond with the jointing of the particular tiles used. In some cases the
channel formed by this tile can be made of sheet lead, or of iron, wrought or cast.
Hip Tiles may in some cases be required, but they will differ very little from
Fig. 3, and chiefly in the increased tapering of their side edges, leaving one wide
and producing one narrow end. This will be easily understood.
All the tiles included in Sheets II & III to be made of thickness and other
dimensions according to different cases. The bevel edges of tiles comprised in
Sheets II & III may be made with a curve or other indentation along the centre of
bevel, so as to accomodate a thicker body of morter than the lapping of bevels
proper would admit of. The whole of the edges described as bevel angles may
also be made chiefly bevel with a small rebate, or chiefly rounded with a small
rebate, or chiefly bevel with a small plough groove.
III Laths. Generally the laths of my roof must be placed closer together covering
more of the under side of the tiles, than laths now ordinarily used, but this involves
no greater cost for wood, as sawing laths wider will admit of sawing them thiner,
yet with the same strength. Galvanized hoop-iron, galvanized sheet iron, or other
material may be used to serve as laths, instead of wood.
Snow and ventilation. I fix a small trap door in the cieling of the upper storey
to be lifted during winter snow-falls, the more quickly to melt the snow away, and
to assist ventilation in the heat of summer, but to achieve the latter some outlet
for the ventilation must be contrived outside the wall, or roof, this can be done
without difficulty.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is :-
1. A roof (designed and constructed as herein described) so much reduced in
height as to be flat, or very nearly flat.
2. The supporting of the flat roof by principals each constituted and formed,
generally, of one plain plank cut and joined in specified manner, Sheet I Fig. 1,
and 2, in certain cases of a plank and a half, Fig. 3, A and B, in other cases of a
plank and a half with contrivances, already specified, added to give increased
bearing power at and near the centre, Fig. 4, in other cases of a plank and a half
so cut and joined, and strengthened by contrivances mentioned next above and
others, (see specification foot of page to middle of page 8) as to augment the
principle's strength at its centre and to its extremities Fig 5.

page_text: 3. The covering of the flat roof securely with tiles mutually attached by various
modes of jointing fully and severally described already, here briefly :-Fig. 1-
Male and female-Male, plough-grooves running down the two slanting edges of
tiles on under side, the top end bevelled on upper side of tile, bottom end bevelled
on under side--female grooved and bevelled to the reverse. Fig 2 Interlocking
by plow-grooves all round, two grooves on upper side of each tile and two on lower,
as already specified. Fig. 3. Interlacing by a rebate all round, in manner already
specified. Fig. 4. Jointed by bevel-angle all round in manner already specified.
Fig. 5. Its body rectangular, jointed all round by simple abutment, with the
addition of a rebate on upper right side and upper side of lower end, this rebate
formed by a rib, as already specified. I also claim the entirely rectangular tile
jointed all round by simple abutment, as already specified, para next under
Sheet II. Fig. 5.
4. The ridge-tile, gutter-tile, gutter-tile-double and hip-tile with their various
modes of jointing with each other and with the staple tiles, both as shewn in
drawings and described in specification. Sheet III. Figs 1, 2 and 3, and para next
below Fig 3.
5. The arrangement by which the two kinds of gutter-tiles are formed and fixed
within all outside walls, so as to supersede the necesity-and remedy the nuisance-
of lateral spouting placed outside the building. Sheet III Figs 2 and 3.
6. The utilizing of the horizontal lower edges of the principles to serve as cieling
joists, acchieving by this arrangment a purely rectangular shape (ceiling included)
for the inside of each and all of the top-storey rooms and passages, and that without
waste of covered space in any part of the roof.
7. The utilizing of the interior walls (notwithstanding their being level and not
triangular) for the purpose of affording bearings, partly or entirely, to sustain the
principals, or some of them, and bearings by immediate-not expensively elaborated
-contact of principal and wall.
8. The raising of all the outer walls more or less above the level of the gutter-
tiles.
Dated this twenty seventh day of October one thousand eight hundred and