ShedSafe training module

1. SHEDSAFE SHED
SPECIFICATION MODULE
2015/16

2. ShedSafe is an independent third party
accreditation program that covers engineering
design , documentation and building specification
for cold formed steel portal frame sheds.
ShedSafe provides Accreditation, for both
manufacturers and shed sellers.
A shed seller can only qualify if they sell sheds
supplied by an ShedSafe accredited
manufacturer as listed on the ShedSafe website
www.ShedSafe.com.au
INTRODUCTION

3. Does completing this module mean your
business is ShedSafe Accredited?
 No. Shed sellers apply for ShedSafe
Accreditation by completing the online
application form, reviewing this Specification
Module, and successfully completing the
Building Specification Questionnaire.
 ShedSafe Accreditation approval is subject to
the program Terms and Conditions, including
payment of annual fees and complying by the
program style guide.
INTRODUCTION

4. Every effort has been made and all reasonable care taken to ensure
the accuracy of the material contained in this module. However, to
the extent permitted by law, the Authors, Editors and Publishers of
this Program: (a) will not be held liable or responsible in any way;
and (b) expressly disclaim any liability or responsibility for any loss
or damage costs or expenses incurred in connection with this
Program by any person, whether that person is the purchaser of this
Program or not. Without limitation, this includes loss, damage,
costs and expenses incurred as a result of the negligence of the
Authors, Editors or Publishers. Should expert assistance be
required, the services of a competent professional person should be
sought.
DISCLAIMER

5. SHED
SPECIFICATION
The shed seller is the best person to obtain
the intended building use, location & site
information to generate the appropriate shed
specification.
The proposed specification should be
confirmed by as correct before the building is
ordered.

6. SHEDS AND
NCC BUILDING CLASSES

7.  The National Construction Code (NCC) is managed by
the Australian Building Codes Board (ABCB) on
behalf of the Australian Government and State and
Territory Governments. The NCC has been given the
status of a building regulation by all States and
Territories. This means it is a regulation.
 The goal of the NCC is to enable the achievement of
nationally consistent, minimum necessary
standards of relevant, health, safety (including
structural safety and safety from fire), amenity and
sustainability objectives efficiently.
 www.abcb.gov.au
WHAT IS THE NCC ?

8.  The NCC defines buildings into 10 Building
Classes.
 Sheds generally fall into class 6,7,8,9 & 10a.
 Class 1 buildings are houses. Numerous
changes are required for a Class10a (non-
habitable) shed to comply with the NCC as a
Class 1 habitable structure.
SHEDS & BUILDING CLASSES

9. GARAGES AND SMALLER SHEDS
 Class 10a sheds are generally garages and
smaller storage sheds

10.  Where used only for storage purposes, farm sheds
are usually Class 10a. (some local authorities
classify as Class 7)
FARM SHEDS

11.  Where selling to the public takes place, Class 6
would apply. If wholesaling, Class 7. If used for
manufacturing, Class 8.
SHED USED FOR BUSINESS

12.  Generally people shelters are Class 9b.
SHELTERS

13. NON-HABITABLE SHEDS
 A Class 10a shed is not required to meet the
Class 1a Housing performance criteria for a
number of factors including the serviceability &
water tightness thus a 10a shed it not compliant
as a house.

14. BUILDING
IMPORTANCE
LEVELS

15.  The NCC assigns four different
building Importance Levels for
structures.
 The assigned Importance level is
consistent with the consequences of
building failure and the risk to human
life (or property).
NATIONAL CONSTRUCTION CODE
IMPORTANCE LEVELS

16.  Level 1- (lowest level) Buildings or structures
presenting a low degree of hazard to life and other
property in the case of failure.
 Level 2- Buildings or structures not included in
importance levels 1, 3 or 4.
 Level 3- Buildings or structures that are designed to
contain a large number of people.
 Level 4- (highest level) Buildings or structures that are
essential to post-disaster recovery or associated
with hazardous facilities.
 Note: The Building Regulator (Certifier ) has the final
call on the Importance level.
IMPORTANCE LEVELS

17. IMPORTANCE LEVELS
 Farm sheds remote from other habitable
buildings are usually Level 1
 Suggested distance to other habitable
structures is 200m
 A group of farm sheds may all be level 1
 School Shelters (with more than 250
students) are required to be Level 3.

18.  The NCC Guide advises Importance Levels
must be assigned on a case by case basis
(NCC Guide Table B1.2a)
 Emergency service buildings including fire
fighting equipment sheds are generally
Importance Level 4, however a lower level may
be assigned by the builder certifier depending
on its actual use.
IMPORTANCE LEVEL 4

19.  The NCC requires that regional wind speeds of
specific probability be used for building design.
THE BUILDING IMPORTANCE LEVEL
DETERMINES THE REGIONAL WIND SPEED
ANNUAL PROBABILITY
OF EXCEEDANCE &
IMPORTANCE LEVEL
REGIONAL WIND SPEED
M/S (meters per second)
Region A Region B Region C Region D
1:100 (IL1) 41 48 - -
1:200 (IL1) - - 64 79
1:500 (IL2) 45 57 69 88
1:1000 (IL3) 46 60 74 94
1:2000 (IL4) 48 63 77 99

20. WIND SPEEDS

21.  There are currently two Wind Codes used in
Australia for design of wind actions.
 AS/NZS 1170.2 Wind Actions Code
 AS4055 Wind Loads for Housing
 Building Certifiers tend to be familiar with
AS4055 due to its use for most houses.
 A certifier cannot reject a shed designed
using AS/NZS1170.2
WIND DESIGN CODES FOR SHEDS

22.  AS/NZS1170.2 is the principal Wind Actions
Code and is applicable for all classes of
buildings.
 Offers flexibility for designers and allows for
a greater range of wind speeds than
AS4055
 Is applicable to Importance Levels 1,2,3 & 4
AS/NZS1170.2

23.  AS4055 Wind Loads for Housing is a Wind
Code developed for housing and can only be
used for Class1 and Class10a structures.
 AS4055 has a limited scope (housing &
smaller sheds) and geometry (length, width
(16m), height & roof pitch). AS 4055 is only
applicable for structures with an Importance
Level of 2.
 Wind classifications are:
 N1 (34m/s) N2 (40m/s), N3 (50m/s) N4 (61m/s)
 C1 (50m/s) C2 (61m/s) C3 (74m/s).
AS4055 WIND LOADS FOR HOUSING

24.  Wind forces are generally the governing factor
when designing a shed, especially in medium
and high wind regions.
 It is essential to establish the site wind speed
for the intended site of the shed.
 If the site wind speed is understated, there is a
increased risk of building failure.
 If the site wind speed is over stated, the shed
may be designed to a higher specification than
is required and have more steel than is required.
WHY IS WIND AN ISSUE FOR SHEDS?

25. THE RELATIONSHIP BETWEEN SITE
WIND SPEED & DESIGN PRESSURE

26.  As the Wind speed increases, the Wind
pressure (KPA) increases at a
disproportionate rate.
(as seen on previous slide)
 When entering the details to your software
program, the input factors will determine
the site wind speed...the higher the
pressure, the stronger the shed needs to
be.
CORRECT SITE WIND SPEED IS ESSENTIAL
TO DETERMINE THE DESIGN OF THE SHED

27.  The SITE wind speed is determined based on the
topographical factors specific to that site.
 The site wind speed is often BELOW the regional
wind speed as the terrain category classification,
and shielding (if applicable) reduce the site wind
speed.
 If the site is on a hill the topography effects would
INCREASE the site wind speed and in some
cases it may exceed the Regional Wind Speed.

DIFFERENCE BETWEEN REGIONAL
WIND SPEED AND A SITE WIND SPEED

28. CORRECT
SPECIFICATION
OF A SHED

29.  WIND REGION Where will the shed be built? Some sheds are
built far from where they are purchased. Will it be subject to
extreme conditions, i.e. snow, cyclones?
 USE & IMPORTANCE LEVEL What will the shed be used
for?
 TERRAIN What is the surrounding area generally like –
acreage, suburban, or rural?
 TOPOGRAPHY Will the shed be built on or near a hill, slope
or escarpment? If so this will affect the specification.
 SHIELDING Is the shed located in a Suburban area ?
WHAT INFORMATION NEEDS TO BE
OBTAINED FROM THE PURCHASER ?

30. There are four wind regions in Australia- A ,B, C & D
WIND REGIONS AS PER
AS/NZS1170.2.2012

31. TC1.5
Open water surfaces
subject to shoaling
waves.
Examples are near
shore ocean water,
large lakes and
unenclosed bays.
TERRAIN CATEGORY –
CONSIDER TERRAIN 500M IN EVERY DIRECTION

32. TC 2
Open terrain including
grassland with
well-scattered
obstructions having
heights generally from
1.5 m to 5 m with no
more than2 obstructions
per hectare.
Examples are open
farmland
TERRAIN CATEGORY –
CONSIDER TERRAIN 500M IN EVERY DIRECTION

33. TC 2.5
Terrain with a few
trees or isolated
obstructions, or fewer
than 10 buildings per
hectare.
Examples are
developing outer
urban areas or
acreage
TERRAIN CATEGORY –
CONSIDER TERRAIN 500M IN EVERY DIRECTION

34. TC 3
Terrain with numerous
closely spaced
obstructions having
heights generally
3m to 10m.
The minimum density
of obstructions shall
be at least equivalent
to 10 house-size
obstructions per
hectare.
TERRAIN CATEGORY –
CONSIDER TERRAIN 500M IN EVERY DIRECTION

35.  The Topography Multiplier is a local
geographic effect. It increases the design
wind speed based on the gradient upwind of
the site.
 Google Earth is useful to evaluate topography.
TOPOGRAPHY
WIND

36.  Some shed software programmes offer options
for topography including:
 Halfway up a hill
 Top of hill
This specifies a topography factor >1.0
 If the topography factor is >1.0, the suitability
of the site wind speed nominated should be
confirmed by a suitably qualified person
TOPOGRAPHY (SIMPLIFIED)

37. The Shielding Multiplier is a local development effect.
It reduces the design wind speed by taking into account
the protection afforded by upwind local buildings. A
Shielding Multiplier of 1.0 should be applied outside
suburban areas unless a lower value is justifiable.
On suburban sites where all adjoining allotments are fully
developed and the average upwind gradient is less than
0.2, a Shielding Multiplier of 0.85 may be applied as
suggested in AS/NZS 1170.2 Supplement 1.
A suburban site is defined as a fully developed area with
a number of rows of streets.
SHIELDING- SUBURBAN SITES

38.  Structures used to provide shielding must be
the same or greater height than the shed they
are intended to provide shielding.
 Structures that provide shielding must be
located < 20h from shielded building i.e. a 4m
high shed requires shielding structures with
80m ( 4m x 20)
 Average Height of shed. The average height
as defined in AS/NZS1170.2 is the average of
the overall shed height and the eaves (gutter)
height.
SHIELDING

39.  Full shielding would apply where there are a
two rows or more of developed structures
on all sides the shed.
 Partial Shielding would apply if there is one
row of structures on all sides.
 A shed built on a site that adjoins an open
area or parkland would have no shielding
FULL, PARTIAL & NO SHIELDING

40.  For wind code AS/NZS1170.2 only permanent
buildings provide shielding, trees and
vegetation don’t provide shielding.
 You can only apply shielding IF you are
certain of the structures surrounding the
proposed site
Shielding is generally only applicable in
suburban areas
SHIELDING

41.  The following information should be
shown by all on engineering plans and
quotations:
 Importance Level
 Wind Region
 Site wind speed in m/s
 Terrain Category
 Topography factor
 Shielding factor
 Internal Pressure Co-efficient
SPECIFICATION INFORMATION

42. EXTREME
CONDITIONS

43. EXTREME CONDITIONS
In cyclonic areas
(Regions C & D) wind
forces are much stronger.
Specific design rules
apply to claddings and
openings.
In alpine areas, sheds are
be required to resist snow
loading.

44.  There are 4 alpine or sub-alpine regions in Australia
 In these areas, snow build-up on roofs can lead to
structural collapse.
 Structures can be designed to resist this load, or to
shed snow to reduce loads
ALPINE AREAS
Classification Area Description Alpine Altitudes Sub-alpine
Altitudes
AN Northern Tablelands
(Guyra area)
NA Above 600 metres
AC Central Tablelands
(Blue Mountains)
NA Above 600 metres
AS Southern Tablelands
(Snowy Mountains)
Above 1200 metres 600 to 1200 metres
AT Tasmania
(Central Highlands)
Above 900 metres 300 to 900 metres

45.  Sheds built in the cyclonic Wind regions C and
D are subject to high wind loads and the risk
of being subjected to impact from debris
during a cyclone of storm.
 The Wind Code AS/NZS1170.2 requires sheds
built in cyclonic regions to be designed for a
“Dominant Opening", unless the whole building
envelope has test certificates to resist wind
driven debris.
CYCLONIC AREAS

46.  A dominant opening occurs when part of the
structure fails, i.e. roller door, plastic roof
sheeting, cladding or is caused by impact
from flying debris.
 A dominant opening does not need to be
large, an open vent may be sufficient to
cause a build up of internal pressure.
DOMINANT OPENING

47. ROLLER
DOORS

48.  Garage Door and Other Large Access Doors
standard AS/NZS4505:2012 was recently revised
and published in February 2013.
 The design wind pressures used in this standard
are consistent the two wind loading codes
AS/NZS1170.2 and AS4055, this was previously
not the case.
 This means that doors complying with the
standard can withstand the same wind rating as
the shed in which it is installed.
 AS/NZS4505:2012 is applicable to all wind
regions A, B, C & D
ROLLER DOORS AND
LARGE ACCESS DOORS

49.  Roller and large access doors supplied in
Cyclonic regions are required by the
National Construction Code to meet the
requirements of AS4505.
 Loads on door in cyclonic regions are
significant and door mullions need to be
designed to resist these forces.
DOORS IN CYCLONIC REGIONS

50. COMPLETION
 Thank you for reviewing this module.
 Please complete the Questionnaire on
the ApplyShedSafe.com.au website.
 Upon successful completion of the
questionnaire, you will receive a
Certification of Completion.
SHEDSAFE SHED SPECIFICATION
MODULE 2014-15