Technical Alerts
BALUSTRADE DESIGN
Since B1 Structure was revised and AS/NZS 1170 was cited by the
DBH from December 2008 we are working to new loadings for
balustrades. In addition the B1/VM1 and the Practice Advisory Note
10 provide design guidance for barriers and details how to apply
the loads.
After some "pushing" from GANZ the DBH have prepared a document
"Guidance on Barriers Design" (Nov 2011) to provide guidance about
barriers and it includes information from and Practice Advisory (PA
10) "Design Guidance for Barriers". These documents are
available from the DBH website and include the GANZ balustrade
design tables. (Refer TB 31))
The result is the Balustrade design charts in section
13.23 are no longer suitable for barrier design.
Glass Safeguarding a fall of 1m or more
Fully Framed Glass
Fully framed glass protecting a difference in level of 1 metre or
more, covered in NZS 4223: Part 3:1999, Clause 310 and Table 3.7
for glass selection, will no longer be part of the Acceptable
Solution B1/AS1 from 31st Jan 2012.
This is because the NZBC Acceptable Solution B1/AS1 Amendment 11
has deleted this clause 310.1 and Table 3.7, because it does not
comply with AS/NZS 1170. This new Amendment 11 was effective
from 1st August 2011 and becomes mandatory from 31st Jan 2012.
It was generally accepted that external curtain wall facades could
have glass that complies with NZS 4223:Part 3:1999, Table 3.7, or
thicker due to high wind loading, to provide adequate protection.
However, this table was established before the new AS/NZS 1170 and
B1/VM1 barrier requirements.
GANZ have prepared a new table FF-1 for fully framed glazing and
this will be added to NZS 4223 Part 3 in the future. This
table is based on the design loads detailed in the DBH Guidance on
Barrier Design (Nov 2011).
Refer also our TB 33 for more information
SLOPED GLAZING
With the citation of AS/NZS 1170 we also have additional live
loads to deal with for roof and canopy design. These are normally
0.5kN or 1.1 kN for occupancy R2 and 1.8 kN for R1 street awnings.
(Refer AS/NZS1170.1 Table 3.2)
These are very restrictive on design and guidance is provided in
the new NZS 4223:Part 4:2008 and our Technical Bulletin 32.
The result is that the Sloped Glazing Design Charts
in Section 13.5 are out of date unless you are designing without
the live loads, using wind and dead load only.
GLASS FLOORS
AS/NZS 1170.1 also introduces new occupancy loadings on glass
floors (table 3.1) and thus the floor design chart in section 13.12
may not be suitable for some loading conditions, so if designing
floors it is best to check with MetroGlass Tech sales and technical
staff.
Metro GlassTech Catalogue and Reference Guide - 6th
Edition
The real problem for designers is "the glass bible" as it is
known, is a little out of date in some sections due to these
changes in NZBC compliance documents and Standards.
We are working on a new version and we have prepared some
Technical Bulletins on some of the major issues and these are
available on request.
If you are working on information from the following sections we
advise you to contact us, and we have "tagged" these sections on
the website version as "out-of-date"
Section 13 Design and Engineering
13.2 Design Properties
13.3 Wind load and deflection
13.5 Sloped and overhead glazing
13.7 Faceted Glazing
13.9 Aquaria
13.12 Glass Floors
13.23 Balustrade and Fence Design
13.25 Balustrade Fixing and fittings
Section 14 Glazing
14.2 Glazing dimensions
14.3 Glass Blocking
14.6 Wet glazing
14.7 Putty glazing
Section 15 Compliance
15.4 Glass standards
15.6 Reglazing
15.10 Sloped glazing calculations
15.11 Human impact chart and tables
15.12 Human impact guide