136 Designing and making shelving arrangements
rungs are made from 9 or 10mm Ø (diameter) dowel
rod – which is commercially available in redwood or
light- coloured hardwood in standard lengths of 2.4m.Construction of the ladder- frames
Figures 7.3(a)(b)(c)(d)(e)(f )(g): As illustrated, each
pair of uprights are drilled right through their faces
with 9 or 10mm Ø dowel- holes, equally spaced at
75mm centres throughout the entire height from
bottom- to top- shelf dowel- bearers. Prior to drilling,
though, the bottom parts of the uprights against the
wall have to be scribed or modified to accommodate
the projecting skirting member; and the top parts
can be prepared for alternative finishes at the same
time. Both of these items are detailed separately in
Figures 7.3(c) to (g).
Each pair of uprights becomes a complete frame
by inserting three end- prepared, projecting dowel-
rungs in position and fixing them through the frame-
sides with 18mm sherardized panel pins. The three
positions for the fixed dowels are the extreme top, the
extreme bottom and a mid- or near mid- area loca-
tion.MID- AREA SHELF- SUPPORTS
If a shelf or an arrangement of shelves has multiple
bearing points or brackets, i.e. one or more inner
supports in addition to a support at each end, as in
Figure 7.2(f ) above and Figure 7.3(b) below, the
shelving will take slightly more load. This is because
of the cantilever affect acting on each side of the
mid- area bearing points, related to compressive and
tensile stresses explained at the start of the chapter.
Alternatively, in these situations, the shelving could be
of slightly less thickness than the calculated thick-
ness determined by the actual span between each of
the multiple supports. These strength- considerations
also apply to bookcase shelves when their rear edges
are held by pinning or screwing through built- in back
panels.
LADDER- FRAME SHELF UNIT
Design was mentioned at the beginning of this
chapter and is now the subject at the end of it. The
illustration below shows part of a simply constructed
ladder- frame shelf unit that I first designed and made
over three decades ago. Similar units made in recent
years have been only slightly modified.
Original concept
Figure 7.3(a): Wall- to- wall shelving was needed in
the recesses on each side of my family’s living room
chimney- breast, above newly built- in storage cup-
boards of about 900mm height. Aesthetically, shelves
supported by wooden end- bearers or indented brack-
ets were not an option – and the other extreme of
using solid bookcase- type cheeks was not quite what
was wanted either. So, with simplicity and economy in
mind, I thought of a ladder- frame design that could
be fixed to each side- wall so that the rungs could
support the shelf- ends.
Frame material
The ladder- frame uprights are made from ex 25 ×
25mm (usually reduced by timber merchants to a 20 ×
20mm par finish) redwood or hardwood, which must
be fairly straight- grained, straight and knot- free. If
either one or both of the end ladder- frames are not
up against a return wall, short lengths of the frame
material are also required for modifications to the
shelf- ends and rear- edges, as detailed below. These
modifications create more connectivity between the
fixed frames and the unfixed shelves. The horizontal
Figure 7.3 (a) Original concept of adjustable wall- to-
wall shelving. Over the years this design – still using the
same sectional- sized timber – has evolved into fixed,
floor- standing units of varying heights (mostly floor- to-
near- ceiling or coving), usually with one or two mid- area
ladder- frames, depending on the overall unit width
required in relation to the span calculations.