Civil Engineering Reference
In-Depth Information
back of the pair of timbers. The horizontal timbers (lintels) spanning the opening will be
fixed to both the internal and external faces of the 290 × 45 posts (see Figure 5.17). The
lintels can initially be fitted to the posts with nails, however it will be necessary to use
metal brackets to bolt the lintels to the posts. Your engineer will provide specifications for
the timber dimensions, the configuration of the metal brackets and the required location
of them. Once in place there will be a space of 290 mm between the two lintels. Blocks are
to be fitted between the two lintels and flush with the top edge of the lintels at 450 centres
along the lintels. The blocks are to be no less than 50 mm smaller in depth than the
lintels. Droppers are then fixed to the side of the block to form the shape over the
opening (see Figure 5.18).
External lintel
Internal lintel
Dropper
Figure 5.18
Noggings and droppers fixed to double lintels
Setting the height of the lintel
Set the height of the lintel to match compressed bale heights. If the lintels are supporting
bales only, think carefully about the appropriate height for the underside of the lintel,
taking into consideration the final shape required above the window. Part of this decision
should account for the required position of window-dressings as it will be necessary to
supply a fixing point for curtain tracks etc. if they are to be fitted against the window
rather than on the internal face of the wall. Figure 5.10 shows a vertical timber above the
window for installation of window dressings against the window. The height of lintels
supporting upper floor joists will be determined by the ceiling height of the ground floor,
as the underside of the upper floor joists function as the ceiling timbers of the ground
floor.
The straw bales above the opening are supported on bottom bale boxing just the
same as on the ground floor. When the lintels also support the upper floor joists the floor
joists are fixed across and to both lintels. Flooring is fitted to the upper floor joists and
the bottom bale boxing is fitted on top of the first floor flooring (see Figure 5.19). The
bottom bale boxing for the first floor can either be skew nailed to the upper floor joists or
