Bridging. As soon as the rough floor is Laid, and before this, if the boards are to be laid diagonally, the floor beams must be bridged, or trussed, as it is sometimes called. This consists in cutting in diagonally between the joists, strips of wood which are nailed securely top and bottom and cross each other between each timber. (Fig. 21.) Some carpenters reason that a piece of plank cut in ver tically between the joists will serve the same purpose, but this is not so. If the floor is Laid square across the joists, the usual way is to take up a board along where the bridging will come. The super intendent should look out that the is well fitted and thor oughly nailed, and continuous from side to side.
Exterior Framing. Next order will come the raising of the exterior vertical frame, and in this relation we will have had a choice of two principles. The first and more common method is called the " full frame" or " braced frame" and consists first, of erecting at the angles of the building, posts 4 X 6 or 4 X S. Between these uprights, at the level of the floors, are run horizontal "girts" which receive the joists of the second floor and into which are framed the door and window studs, and at the top of the wall a plate is set in a similar fashion. The angles made by these tiinbers with the posts, are braced by diagonal pieces framed or spiked to the horizontal timber and post. (Fig. 22.) In the other method of exterior framing, called "balloon fram ing," the girts are omitted and the studs run from sill to plate. The usual way of forming the plate in this construction is to spike on the top of the studs a 2 X 4-inch piece, and on top of this another 2 X 4-inch piece, breaking joints and overlapping at the angles.
Provision for supporting the intermediate floors is made by spiking a board 1 X 6 inches into notches cut in the inside of the studs so that the top of the board will be an inch above the bottom of the floor joists. (Fig. 23.) This board is called a ledger-board and is one of the weak points of balloon framing, not in the weight carrying sense, but in case of fire, as it does not prevent the spread of the fire as would a solid girt, being more easily consumed and doubtless would let the floor fall. The floor joists should be notched over this ledger-board, which should be kept back a little from the inside face of the studs to allow space for the mortar to clinch. Another weak point is the omission of braces, which if used can only be short ones at the top and bottom, and are usually omitted in this kind of frame. A substitute for braces sometimes used, is a stout strip usually one inch by three inches cut diag onally into the outside of the studs and spiked to each. This makes a very strong brace but weakens the studding. The fact that the studs of a balloon frame run from top to bottom, requires that the windows should be as nearly as possible over each other so that one set of window studs will serve for both upper and lower windows.
The erection of the outside frame should be carefully watched to see that the door and window studs, at least, are tenoned head and foot, that all the braces are put in and properly framed, and that all the joints are snug and well pinned, the openings in the proper places, and the fram ing plumb and rigid. Nothing is more annoying than to find, after the outside frame is all up, that a window or door has been framed out of place, and although the builder may be obliged to rectify the mis take at his own expense, it can only be done by patching somewhere and the owner is quite likely to feel that the error might have been prevented by the more careful oversight of the architect. As soon
as the frame is set up, in our case a full frame, which can be set up a story at a time (the attic joists only being carried on a ledger), the outside boarding is put on. Spruce or hemlock is used for this mainly, but it must be mill-planed to an even thickness so as to give a true surface for the outside covering of clapboards or shingles. (We find that the boarding is specified to be matched and laid diago nally upon the walls and square-edged for the roof. The reason for not matching the roof being that the cracks in the square-edged boarding will allow circulation of air under roof shingles and preserve them much longer than if matched boarding were used.) When the first story studding is set and the gists are on, the inside bearing partitions must be set up to give a support for the inner ends of the second floor joists. It will not be necessary to set up all the studs of these partitions at first, but the partition caps should be run and studs set up at three or four-foot intervals and set as nearly as possible in their proper places, to avoid doing the work over again. As soon as this is done the second floor joists can be set and bridged and with the outer walls car ried up to the plate and another parti tion in the second story set, the attic joists may be put on and the building made ready for the roof. At this juncture we are approached by the foreman who holds in his hand a smooth board upon which he has drawn a sketch of the attic joists and ledger board which he submits for our opin ion. We examine his drawings and find that he has represented a ledger= hoard 2 X 3 inches notched into the studs one inch and up into the joists two inches, making the bottom of this ledger flush with the bottom of the ceiling furring. (Fig. 24.) This method he puts forth as haring nearly equal strength of the 1 X 6-inch which is generally used, and the merit of not presenting so broad a surface behind the lathing a t the top of the second story, which destroys in a measure the key of the plaster. We consider carefully all of the features of this method and admitting that it has these features to recommend it, we can praise the ingenuity of the device. If we were to run heavy cornices at the top of our second story we would be inclined to adopt the sketch, but as we shall run only a picture moulding in the angle which will be helped rather than hurt by the presence of the wood the lathing at that point, we decide in favor of the usual way of putting in the 1 X (-inch ledger, but tell the foreman to notch the studs 1 k inches deep so that there will be a space between the laths and the ledger for a key to the plaster. (See Fig. 23.) An important matter in carrying the outside and inside supports from bottom to top is to see that the amount of shrinkable timber is as nearly as possible the same in both outside and inside walls. For this reason the corm mon practice of setting the partition studs upon a horizontal piece laid on the under floor should be avoided.