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From page 22
An exposed timber frame may require maintenance to maximise longevity.
Albeit, the lightweight steel frame does
require specialised tools, and this can cause
challenges on site. “Should drills not be
battery operated, one would need a
generator on site to power the tools. In
addition, structures that require lightweight
steel trusses have large open spaces and
are normally high buildings, so safety
equipment is a must,” states Curry.
It’s nature
24
APRIL 2018
RESIDENTIAL // COMMERCIAL // INDUSTRIAL
From information gathered about the two
materials, clearly none fares better than the
other. This factor is determined by the
application. Both materials offer great
advantages as well as added aesthetic
appeal. Whether you choose timber or
steel, you sure have a winner in your hands.
It is clear why they share the market.
OPTIONS TO INCREASE
COST EFFICIENCIES
• Timber trusses with LGS top-hat
(purlins / battens, bracing, runners)
• Timber trusses with LGS girders
• LGS trusses with MS girders
Source: MiTek
LC
Method of installation plays a role in
whether the frame will require maintenance
or not. “If LGS structures are installed as
intended in an enclosed envelope, there is
no maintenance required at all,”
says Schlüter.
Curry adds that interval inspections are
required to ensure structural adequacy.
Timber absorbs water, and this may cause it
to creep overtime, but it generally lasts long
if the design is correct. “Overhangs on
trusses exposed to the elements need to be
treated with creosote to protect the timber
from deteriorating over time. Should the
roof be waterproof, the timber inside the
structure does not need any treatment over
time. Good practice is to inspect the
structure for cracks and buckling annually
to ensure structural competence,”
Curry advises.
Look and feel
Timber is pre-fabricated, and this means
that modifications can’t be done on site.
COST EFFICIENCIES OF ROOF STRUCTURES
TIMBER NAIL-PLATE TRUSSES LGS TRUSSES
Timber material costs less per metre Material costs more per metre
Less strength (5mpa) More strength (550mpa)
Cannot be site assembled Easily assembled on site
Site modification not easy Suitable up to 40m spans
Remedial work not easy Easy site and remedial work
Longevity limited Longevity guaranteed
Source: MiTek