Even in superior buildings windows may necessarily be fixed without linings. This occurs when the wall is thin, affording barely space for the boxed frame, together with a sufficient thickness of brickwork for the reveal.
Fig. 549 is a section of the upper portion of a window, in 9-inch brick wall.
The frame is secured in position at the sides by being nailed obliquely through the inside lining to wood bricks built into the reveal, and at the head by being nailed through the inside lining to the wood lintel.
In this case the head is furnished with a top lining (tl); the inside lining is secured to this and to the lintel, and a bracket similar to that in Fig. 545 is therefore unnecessary.
It will be seen that Figs. 545 and 549 give illustrations of the different methods in which the weight of the back of the wall above the opening is supported. In Fig. 549 there is a wood lintel (WL), relieved by a rough segmental arch of the description shown in Fig. 99. In Fig. 545 Y is a flat arch for which a concrete beam is sometimes substituted, thus in either case dispensing with the wood lintel, the evils of which have been pointed out at p. 11.
If the method illustrated in Fig. 549 were applied to the thicker wall shown in Fig. 545, two lintels of wood or breeze would be required to support the back of the wall above the opening. Such a case is shown in Fig. 543. The under sides of the wood lintels are either hacked or lathed to form a key for the plaster soffit; or in superior work they are covered by a wooden soffit lining, as described in Part II.
These are constructed in exactly the same manner as those just described, and so are the frames to contain them; but the upper sash, instead of being suspended, is fixed, and prevented from descending, by stops nailed under its bottom rail, the lower sash only being hung with counterbalance weights, as above described.
In some cases, however, it is more convenient to fix the lower sash, the upper one being hung in the usual manner.