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see what could be done to remedy these difficulties and this paper is descriptive of the weave shed that was constructed, and as the desired results have been accomplished, it may be of interest to the members of this Association.
I will not go into a discussion of the reasons for the use of what is known as the sawtooth construction of skylights for weave sheds because everyone familiar with this class of building knows it to be the only practical way of properly lighting such a building. The advantages of the sawtooth form of skylight over the ordinary hipped skylight are north light and elimination of the direct rays of the sun.
I. Practically all of the troubles of the sawtooth method of skylight construction are caused by severe winter weather conditions and can be classed under two heads, i. e., leakage caused by severe snow, ice or sleet storms, and inside condensation caused by low outside temperature.
When snow and ice accumulate on a sawtooth roof, they melt near the peak of the roof and run down towards the gutter. the water runs into the shadow caused by the peak of the next sawtooth, it will freeze on the lower portion of the roof and in the gutters. This alternate freezing and thawing causes the water to back up under flashings, and it is therefore necessary to make them absolutely tight.
2. Figure 1 is a detail of gutter, glass, stile and ridge construction, as adopted for this weave shed. It will be noted that the toe of the truss is supported by an I-beam column and that the gutter is supported by light cross beams. These beams are set at different heights in the length of the gutter, so that proper pitch is obtained from the high point of the gutter to the point where the water is taken down.
The curb or bottom part of the skylight sash is made of 4′′ Michigan pine, bevelled at a sharp angle at its top to permit the water of condensation to readily run off the curb, and it is also grooved at the lower part of this bevel to form a drip edge, so that all condensation on the glass will drip into a small copper gutter which is carried the whole length of this sill. This copper
CROSS SECTION OF STILE
gutter is connected by means of small lead pipes to the regular roof downtakes.
3. The gutter proper is made as follows:
The corners formed between the bottom of the gutter and the curb on one side, and the gutter and the flat roof on the other, are filled with a fillet of wood of curved shape. Then sheet
asbestos 1-16′′ thick is laid, extending up to within 3" of the glass on one side, and 2′-0′′ on the flat roof on the other side. On this asbestos is then laid galvanized iron of about No. 24 gauge, extending to the same height as the asbestos paper. This galvanized iron is nailed to the roof. The object of the galvanized iron is to make a gutter firm and smooth to walk upon, and cover any imperfections in the plank. This is especially necessary when the plank shrink, as otherwise anyone walking in the gutter would, in time, puncture the roof, either through the cracks between the planks caused by shrinkage, or through imperfections in the plank. The asbestos paper is first laid underneath this galvanized iron, in order to prevent the moist air from the room below finding its way through the cracks in the plank, striking the galvanized iron and condensing and dripping back into the room below. After the gutter is thus prepared, it is ready to receive the regular five-ply or pitch roofing. In the gutter itself six-ply is used, to strengthen the roof at this point. The roofing material itself should be thoroughly nailed and mopped. Immediately underneath the lower end of the glass there is a flashing of galvanized iron, which is cut into the sill of the skylight by a specially prepared tool. The wood is simply opened by a thin wedge and the galvanized iron driven into this opening. This galvanized iron extends down and over the roofing material and is thoroughly nailed throughout its entire length. It is then mopped with pitch to make it watertight.
4. To determine the best method to use for the stiles of the skylight, I placed in the old weave shed a system of metal bars of well known make. This was during the winter. It was found that the drainage from this metal bar to the outside froze and the water of condensation was delivered into the room instead of outside the building. In severe weather, moisture would collect on this bar and icicles would form on the lower part of it. I therefore discarded the metal frame.
5. The stiles or bars of the skylight were made of white pine, firmly fastened to the curb and ridge with brass screws. Both
the curbing and stiles were kiln dried and were shellaced before delivery on the roof.
6. The glazing is double; the inside light is of 4 inch factory ribbed glass, and the outside of plain double-thick glass. The outside glass is held from slipping downwards by means of brass screws. Both lights were thoroughly bedded in putty and the outside light was properly drawn. The putty used contained 33 per cent. of white lead.
7. As is shown in Figure 2, the gutters are drained at various points throughout their length. A copper bowl is set into the roof and this bowl is set down into the plank so that there will be no accumulation of water immediately around it. From this copper bowl a lead pipe is connected to a down-take column, which in this instance, is made of channel iron. The down-take pipe passes within this column to the drainage pipes in the base
ducting material. A shield of galvanized iron is placed over the down-take pipe where it passes through the channel iron column. This shield is fastened to the down-take column to protect the copper down-take from injury. One of these columns is shown. in the forepart of Figure 2.
8. The roofing material used upon this weave shed was fiveply asphalt, and especial care was taken in nailing the felt to the roof. The roof has now passed through three (3) winters and does not show as yet any signs of deterioration. If it lasts through another winter I shall consider it good for the purpose.
9. The supporting work of the roof and floor is of steel, Figures 2 and 3. The columns are I-beams, these being used because they were narrow and allowed the looms to be set close together. The columns are continuous from the toe of the skylight to the foundation in the basement, and are bolted to these foundations. The main floor is supported upon I-beam stringers