FIRE-PROOF HOUSES.
The attempts which have been made to render houses fire-proof are so
intimately connected with the construction of dwellings, that it will
be proper to give a few brief details on the subject. There are many
difficulties attending these attempts; for so long as wood forms the
chief inner frame-work of a house, there will always be considerable
liability to destruction by fire. Most of the proposed plans have had
relation to the coating of the wood with some substance which should
render it less inflammable, while others have been directed rather to
the rejection of combustible substances from the list of those used in
house-building.
So long back as 1775, Mr. Hartley made several trials in order to
test the efficacy of a method invented by him for that purpose. Thin
iron plates were nailed to the top of the joists; the edges of the
sides and ends being lapped over, folded close, and hammered together.
Partitions, stairs, and floors were proposed to be defended in the same
manner. The plates were so thin as not to prevent the floor from being
nailed on the joists in the same manner as if the iron were not used;
and the plates were kept from rust by being painted or varnished with
oil and turpentine. Mr. Hartley had a patent for this invention; and
Parliament voted a sum of money towards defraying the expense of his
numerous experiments. It does not, however, appear that the plan was
permanently adopted.
About the same period, Lord Mahon, afterwards Earl Stanhope, a
nobleman possessing a highly inventive tact in mechanical matters,
brought forward another method having the same object in view. This
method was of a three-fold character, comprising _under-flooring_,
_extra-lathing_, and _inter-securing_.
The method of under-flooring is either single or double. In single
under-flooring, a common strong lath of oak or fir, about one-fourth
of an inch thick, should be nailed against each side of every joist,
and of every main timber, supporting the floor which is to be secured.
Other similar laths are then to be nailed along the whole length of the
joists, with their ends butting against each other. The top of each of
these laths or fillets ought to be at an inch and a half below the top
of the joists or timbers against which they are nailed; and they will
thus form a sort of small ledge on each side of all the joists. These
fillets are to be well bedded in a rough plaster when they are nailed
on, so that there may be no interval between them and the joists; and
the same plaster ought to be spread with a trowel upon the tops of
all the fillets, and along the sides of that part of the joists which
is between the top of the fillets and the upper edge of the joints.
In order to fill up the intervals between the joists that support the
floor, short pieces of common laths, whose length is equal to the width
of these intervals, should be laid in the contrary direction to the
joists, and close together in a row, so as to touch one another; their
ends must rest upon the fillets, and they ought to be well bedded in
the rough plaster, but are not to be fastened with nails. They must
then be covered with one thick coat of the rough plaster, which is to
be spread over them to the level of the tops of the joists; and, in a
day or two this plaster should be trowelled over, close to the sides of
the joists, without covering the tops of the joists with it.
In the method of double-flooring, the fillets and short pieces of laths
are applied in the same manner as here noticed; but the coat of rough
plaster ought to be little more than half as thick as that in the
former method. Whilst the rough plaster is being laid on, some more of
the short pieces of laths must be laid in the intervals between the
joists upon the first coat, and be dipped deep in it. They should be
laid as close as possible to each other, and in the same direction with
the first layer of short laths. Over this second layer of short laths
there must be spread another coat of rough plaster, which should be
trowelled level with the tops of the joists, without rising above them.
The rough plaster may be made of coarse lime and hair; or, instead of
hair, hay chopped to about three inches in length may be substituted
with advantage. One measure of common rough sand, two measures of
slaked lime, and three measures of chopped hay, will form in general
a very good proportion, when sufficiently beaten up together in the
manner of common mortar. The hay should be put in after the two other
ingredients are well mixed up together with water. This plaster should
be made stiff; and when the flooring boards are required to be laid
down very soon, a fourth or fifth part of quicklime in powder, formed
by dropping a small quantity of water on the limestone shortly before
it is used, and well mixed with this rough plaster, will cause it to
dry quickly. If any cracks appear in the rough plaster work near the
joists, when it is thoroughly dry, they ought to be closed by washing
them over with a brush wet with mortar wash: this wash may be prepared
by putting two measures of quicklime and one of common sand into a
vessel, and stirring the mixture with water till the water becomes of
the consistence of a thin jelly.
Before the flooring boards are laid, a small quantity of very dry
common sand should be strewed over the plaster work, and struck smooth
with a hollow rule moved in the direction of the joists, so that it
may lie rounding between each pair of joists. The plaster work and
sand should be perfectly dry, before the boards are laid, for fear of
the dry rot. The method of under-flooring may be applied to a wooden
staircase, but no sand is to be laid upon the rough plaster work. The
method of extra-lathing maybe applied to ceiling joists, to sloping
roofs, and to wooden partitions. The third method, which is that of
inter-securing, is very similar to that of under-flooring; but no sand
is afterwards to be laid on. Inter-securing is applicable to the parts
of a building as the method of extra-lathing.
Such is a general outline of the modes proposed by Lord Mahon for
rendering houses fire-proof; in which it will be seen that the
safeguard consists in the use of a non-combustible material, with, and
among, and between the pieces of wood forming the frame-work of a house.
The more recent attempts to gain the same object by means somewhat
similar have been very numerous; some of which we may here notice as
examples of the whole.
An American patent was granted in 1837 to a Mr. Louis Pambœuf, for
the invention of a fire-proof paint. The mode of preparing it is thus
described. A quantity of the best quicklime is selected, and slacked
with water in a covered vessel; when the slacking is complete, water,
or skimmed milk, or a mixture of both, is added to the lime, and
mixed up with it to the consistence of cream. When milk is not used a
solution of rice paste is employed, obtained by boiling eight pounds
of rice to every hundred gallons of paint. When the creamy liquor is
prepared, alum, potash, and common salt are added, in the proportion of
twenty pounds of alum, fifteen pounds of potash, and a bushel of salt,
to every hundred gallons of the paint. If the paint is to be white, six
pounds of prepared plaster of Paris and the same quantity of fine white
clay are added to the above proportions of the other ingredients. All
these ingredients being mingled, the mixture is strained through a fine
sieve, and then ground in a colour-mill.
When roofs are to be covered, or when crumbling brick walls are to be
coated, fine white sand is mixed with the paint, in the proportion of
one pound to ten gallons of paint; this addition being made with a view
to giving the ingredients a binding or petrifying quality. In applying
this paint, except in very warm weather, it is prepared in a hot
state; and in very cold weather precautions are necessary to prevent
it from freezing. Three coats of this paint are deemed in most cases
sufficient.
In another variety of this paint oil is the chief liquid ingredient. To
prepare it forty gallons of boiled linseed oil are mixed with slacked
lime to the consistence of a paint; and to this are added two pounds
of alum, one pound of potash, and eight pounds of common salt; or good
wood-ashes may be substituted for the potash. This paint is used in the
same manner as other paint; and any colour may be obtained by adding
the usual pigments to the composition.
The preparation of a kind of paint containing alkalies seems to have
been a favourite measure among inventors of “fire-proof” composition;
for many of the modern projects have had this for its basis. But in
most cases there have not been means for determining the degree of
efficacy possessed by these compositions. There were, however, a few
years ago trials made of rather an interesting character, which were
described in the public journals, and which were of the following
nature.
In 1838, a company was formed for the sale and use of a composition
of this kind, and an experiment was made in the Clapham Road to show
its efficacy. The house, which was a small one, had been built in the
usual way, with the intention of being fitted up in the ordinary style.
While yet a mere shell, all the boards, timbers, floors, ceilings,
stairs, and wood-work generally, were coated thickly with a greyish or
slate-coloured composition, which dried to a state of great hardness.
On a particular day the upper floor was covered with shavings in great
abundance, to which a number of deal planks were subsequently added.
The first floor front room was fitted up as a chamber, with bed and
furniture, chairs, tables, &c., as nearly as possible in the usual
style. The shavings and wood on the upper floor were then kindled, as
were also planks and shavings placed on the floor of the furnished
room. The consequence of this was that the two rooms speedily exhibited
a blaze of light: the whole of the furniture (purposely selected of an
inexpensive kind) being ignited. The flames burst from the windows; but
although the entire contents of the room were consumed, the fire did
not communicate to the floor above, nor to that beneath, nor even to
the other room on the same floor. Several small parcels of gunpowder
were introduced between the ceiling of the burning room and the floor
of the room above it; but they did not ignite; nor were the other
parts of the house injured in any material degree.
Another trial took place at the White Conduit Gardens; where two close
wooden buildings, of the size and shape of sentry boxes, were placed in
the grounds. One of them was coated on the inside to the thickness of
about an eighth of an inch with the composition, and was also partially
covered on the outside; while the other was left in the plain wood
state. A flooring was placed at about the centre of each of these, and
through the holes in front shavings were put and then ignited. The box
which was not coated with the composition was soon in flames; while
the fire in the other went out without having had any effect upon the
general structure. The building which was in flames was then placed
contiguous to the partially-coated outside of the other, and although
it was not materially injured, the exterior coating peeled off in some
places, and the wood became charred; the interior, however, appeared
perfectly uninjured by the flame.
If the results of these experiments were really such as the description
would seem to imply, it might excite surprise how it happens that no
practical results have followed. But there are always numerous reasons
why an experiment, which succeeds under circumstances _made_ for the
occasion, should not be available in practice; and it is probable that
some such discordance may exist here. Perhaps the mode in which we may
more consistently look for the practical attainment of the object in
view is by the adoption of some improved mode of building, in which
either wood is not employed at all, or, where sparingly used, measures
are taken to shield it from the action of fire. One such method is
Leconte’s, described as follows.
This plan consists in the employment of iron frames to receive concrete
matter for forming the walls. The basement story of the building is
constructed according to the ordinary methods up to one foot or more
above the ground. On the basement so constructed is to be erected the
patent wall, formed of frames entirely of cast-iron, in one or more
pieces, or a combination of cast-iron and wrought-iron plates. These
frames are to be set one on the other until the required height is
attained, the necessary stability being obtained by means of steady
pins at the corners of one frame fitting into holes made in the
corners of the frame which is opposed to it. Suitably-shaped frames
are employed for the internal partition walls, and for doorways,
window-frames, &c. The flues of the chimneys are formed of iron or
other metal pipes, placed in the thickness of the walls. When the
required elevation is obtained, a concrete of any suitable material is
poured into the framing, and fills up the vacant space, giving firmness
and solidity to the structure; the concrete being made of gravel and
lime. To give steadiness, lead is to be introduced between the joinings
of the iron-work. The doors and window-frames are to be fastened to
the walls by any of the usual known methods. The main beams and cross
beams of floors and roofs may be of cast-iron, or formed of iron and
wood; or they maybe formed of one or more pieces of plate-iron, bent up
into an oval form, and straightened by an iron or wooden bar passing
through them lengthwise, the upper edges of the metal being turned
over to increase the strength. In the interval between the beams there
are to be iron rods running in various directions, and supporting a
metallic wire-work, which forms the foundation for the ceiling. Similar
wire-work is to be employed in lieu of laths for plaster surfaces. All
the iron-work is to be painted over with some suitable composition to
prevent oxidation.
A plan for the same purpose has been proposed by Mr. Varden as
follows:--“It appears probable that common fir or oak joists with
their lower edges chamfered, and coated over with a mixture of alum,
black lead, clay, and lime, or some similar composition, would (if
closely floored above with earthenware tiles, bedded all round into
the plastering, the joists being made air-tight) resist the action
of flames, at least for a considerable time. Fire could not descend
through such a flooring so as to communicate with the rooms below, till
the tiles used in it had become red-hot; neither could it ascend until
the tiled floor above gave way, from the burning of the joists; which,
if coated as proposed, would not take fire from below till the tiling
over them acquired a sufficient heat to cause the distillation of the
turpentine from the wood. In general, there is not furniture enough of
a combustible nature in any room to do this. The battening against the
outer walls might be of larch, as that wood burns less freely than most
others; but if the walls were brick, or lined with brick, battening of
any kind will be unnecessary. If this plan should be thought likely to
answer the end proposed, houses built in the common manner might be
altered at a moderate expense, by taking up the boarded floors, and
substituting earthenware tiles.”
Another Plan, proposed by Mr. Frost, consists in forming the floors of
rooms of hollow earthenware tubes embedded in cement, combined so as to
form a sort of flag-stone, covering the whole floor. These hollow tubes
are square in section, about an inch and a half on the side externally,
with a tubular space of an inch and a quarter on the side internally;
they are formed of brick earth, prepared in a superior manner, and
pressed through moulds by machinery; and their length is about two
feet. In forming a floor of these tubes, the centering, after being
prepared and fixed in the usual manner, is first covered with a coating
of cement of a quality sufficiently fine to form the ceiling of the
apartment to be floored over; and if it is desired that there should
be mouldings or ornaments in this ceiling or its cornices, moulds for
them can be placed in the centering, so as to form a part of it. One
or two coats of cement having I then been laid over the centering, a
stratum of the square tubes laid side by side, and breaking joint,
is next embedded in fine cement, and the interstices between them
also filled in with that material. One thin coating of cement is then
laid over the whole stratum; and in a week, when this is dry, another
stratum of tubes is laid over the first in a contrary direction, bedded
and filled in with cement as before, and finished by a coating of the
same material. This, when dry, may have a second coating to serve as
the floor of an upper apartment, or the covering of a roof, as the case
might be.
Mr. Loudon gives descriptions of two methods, the one for building
houses in general fire-proof, and the other for imparting that
property to houses already built. He considers the two main points
for consideration to be, to have staircases of iron or stone, or both
combined, and to avoid having any hollow partitions or floors. A house
having a stone or iron staircase, and having all the partitions either
of four-inch brick-work, or of brick nogging, in whatever way it might
be set on fire, could hardly be burned down, if ordinary exertions were
made to extinguish the flames. One apartment might be set on fire, but
before the flames could spread to the one under or over it, or to a
staircase adjoining it, the fire might be extinguished. In a house so
constructed, there would be no piece of timber that was not in close
contact with mortar, at least on one side; and all the strong pieces
of timber, such as joists, rafters, quartering in partitions, &c.,
would be closely embedded in mortar on two sides. Where the partition
could not be made entirely of brick, the interstices might be filled
up with a mortar prepared of clay with a small proportion of lime. The
same material might be filled in between the joists, and where it was
desired to render the roof fire-proof, the rafters might be made of
iron, or the space between wooden rafters might be filled in with thin
mortar. This mode of proceeding would lengthen the time required for
the drying of a newly-built house, and would also add somewhat to the
expense; but it is conceived that the increased safety would more than
counterbalance these inconveniences.
In respect to the means of giving a fire-proof quality to a house
already built, Mr. Loudon remarks:--“All the interstices between the
floors, in the partitions, and in the roof, where there was a ceiling
formed to the rafters, might perhaps be filled in with earthy matter
in a state of powder. This powder might be clay or loam mixed with
a small proportion of Roman cement; it might be injected into the
vacuities, through small orifices, by some description of forcing-pump
or bellows, which, while it forced in the powder, would permit the
escape of the air; and, while this operation was going forward steam
might be injected at the same time, so as to mix with the mortar and be
condensed by it; by which means the whole mass would be solidified with
a minimum of moisture. In short, in rendering houses fire-proof, the
next important object to using fire-proof materials, is that of having
all the walls and partitions, and even the steps of wooden staircases,
filled in-with such materials as will render them in effect solid. On
examining into the causes of the rapidity of the spread of the flames
in London houses when on fire, it will almost invariably be found,
that whatever may have occasioned the fire to break out, the rapidity
of its progress has been in proportion to the greater or less extent
of the lath and plaster partitions, the hollow wooden floors, and the
wooden staircases. Were the occupiers of houses sufficiently aware of
the danger from lath and plaster partitions, especially when inclosing
staircases, they would never occupy such houses, or, if they did, they
would not give such rents for them, as they would for houses with
brick-nogging partitions. It appears to us to be the duty either of the
general or local government or police to see that no houses whatever
are built without stone or iron staircases; and that no partitions and
floors are made hollow; or, if they are, that the materials should
be iron and tiles, or slates, or stones, or cement, or other earthy
composition.”