Page:Architectural Review and American Builders' Journal, Volume 1, 1869.djvu/714

 572 Tlie Architectural Review and American Builders' Journal. [Mar., fact; and, although the continuous pass- age of timbers far into part}r-walls is (let us hope) very seldom to be seen, yet, that such a practice exists, the de- structive conflagration alluded to very indubitably shows. But, apart from this extreme case, it is a very general prac- tice to let flooring joists into the wall at least four inches ; which being the case on both sides of a party-wall, it follows that a twelve-inch wall will thus be reduced in thickness between said joists to four inches ; or the width of a single brick ! When those joists are destroyed, how can such a wall stand ? Even outside, or main walls, are so much weakened by the destruction of the flooring-timbers, on account of the holes left in them reducing their thick- ness, that they frequently totter to the ground, and in comparatively few in- stances is it safe to reconstruct on them. Now, there is either a necessity for extra thickness of party-walls, to meet this deduction for joist-beds ; or, there is more safety in careful corbeling under the lower line of the joists; thus avoid- ing the practice complained of, so that the destruction of the joists would not leave the wall diminished in thick- ness. As to the use of timber in flooring- joists, we propose to make it nearly unassailable by fire, at an expense not greater than that incurred in insurance policies. Nor is this a mere theory ; the thing has been already accomplished in two instances in this city, once in the residence of Mr. Joseph Harri- son, Jr., on Eighteenth street, opposite Rittenhouse Square, and again in the Washington Buildings, on Third street, near Spruce. The modus operandi is simply, as shown in Fig. 1, to encase each joist in iron, up to, say, three inches of the top, and set phites of iron between the joists reaching to the top of the bridging- course. Fill in the space between the top of the iron casing and the iron plates with concrete, or plaster of Paris which has been used in a stereotype foundry, leaving an open space between the flooring and this concrete or plaster. Referring to Fig. ], AAA are the Joists. B, the Bridging. C, the Con- crete. D, the Flooring. Previously to using the iron casing on the joists in the residence alluded to, a test was made, by casing a piece of tim- ber in sheet-iron, and submitting it to the action of a strong fire for a consider- able time. The result was perfectly satisfactory The timber, on being ex- amined, was found to be but slightly charred. Fig. 2 represents the Joist in its wall- hold, with the tail beveled. A, the Wall. B, the Joist. C, the Corbeling, faced with cornice. Fig. 3, a Section of Joist in wall-hold, according to the prevailing method. There is another improvement, which we would suggest, in reference to this liability to destruction by fire. It is, that the cornice should be made inde- pendent, as it were ; simply attached to the wall and secured there ; instead of being directly connected, as at present, with the rafters. Our suggestion can be at once apprehended by a glance at Fig. 4, Section and Elevation. A, the Wall. B, the Bracket or Look- out, held by the iron-strap C, shouldered to the wall, running through, and secured on the inside with nut and washer. D, Rafter. E, Face of Cornice. F, Bracket. G, Moulding. H, Face of Bracket. It is evident, that the burning of a wooden cornice so constructed could not communicate fire to the roof; and that there would be no further detriment to the building, than the destruction of such cornice, which, when burned, would be sure to fall to the ground, without doing injury to the wall. The blocking- course, or parapet, above this cornice, could, if thought advisable, be built so low, as not to show above the outlines of the latter. Thus, we not alone have the required appearance, but — what is better — strength and security as well.