NCC 2019 Volume Two
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Part 2.2 Damp and weatherproofing
Explanatory information:
Explanatory information:
Objective
O2.2
The Objective is to—
- safeguard occupants from illness or injury and protect the building from damage caused by—
- surface water; and
- external moisture entering a building; and
- the accumulation of internal moisture in a building; and
- discharge of swimming pool waste water; and
- protect other property from damage caused by—
- redirected surface water; and
- the discharge of swimming pool waste water.
Functional statements
F2.2.1 Surface water
A building including any associated sitework is to be constructed in a way that protects people and other property from the adverse effects of redirected surface water.
F2.2.2 Weatherproofing and dampness
A building is to be constructed to provide resistance to moisture from the outside and moisture rising from the ground.
Limitation:
F2.2.2 does not apply to a Class 10 building except where its construction contributes to the weatherproofing of the Class 1 building.
F2.2.3 Drainage from swimming pools
Adequate means for the disposal of swimming pool water and drainage is to be provided to a swimming pool.
Performance Requirements
P2.2.1 Rainwater management
(a)
Surface water, resulting from a storm having an average recurrence interval of 20 years and which is collected or concentrated by a building or sitework, must be disposed of in a way that avoids the likelihood of damage or nuisance to any other property.
(b)
Surface water, resulting from a storm having an average recurrence interval of 100 years must not enter the building.
Limitation:
Limitation:
P2.2.1(b) does not apply to a Class 10 building where in the particular case there is no necessity for compliance.
(c)
A drainage system for the disposal of surface water resulting from a storm having an average recurrence interval of—
(i)
20 years must—
(A)
convey surface water to an appropriate outfall; and
(B)
avoid surface water damaging the building; and
(ii)
100 years must avoid the entry of surface water into a building.
P2.2.2 Weatherproofing
A roof and external wall (including openings around windows and doors) must prevent the penetration of water that could cause—
(a)
unhealthy or dangerous conditions, or loss of amenity for occupants; and
(b)
undue dampness or deterioration of building elements.
Limitation:
Limitation:
P2.2.2(a) does not apply to a Class 10 building except where its construction contributes to the weatherproofing of the Class 1 building.
P2.2.3 Rising damp
Moisture from the ground must be prevented from causing—
(a)
unhealthy or dangerous conditions, or loss of amenity for occupants; and
(b)
undue dampness or deterioration of building elements.
Limitation:
Limitation:
P2.2.3 does not apply to a Class 10 building where in the particular case there is no necessity for compliance.
State and Territory Variations
State and Territory Variations
In South Australia delete P2.2.3 and insert SA P2.2.3 as follows:
SA P2.2.3 Rising damp
- Moisture from the ground must be prevented from causing—
- undue dampness or deterioration of building elements; and
- unhealthy or dangerous conditions, or loss of amenity for occupants.
- Barriers installed to prevent transfer of moisture from the ground must have—
- high resistance to moisture penetration; and
- high resistance to damage during construction; and
- high resistance to degradation by dissolved salts.
In New South Wales delete P2.2.3 and insert NSW P2.2.3 as follows:
NSW P2.2.3 Rising damp
- Moisture from the ground must be prevented from causing—
- unhealthy or dangerous conditions, or loss of amenity for occupants; and
- undue dampness or deterioration of building elements.
- Barriers installed beneath slab on ground construction for the purposes of (a) must have a high resistance to damage during construction.
Limitation:
Limitation:
P2.2.3 does not apply to a Class 10 building where in the particular case there is no necessity for compliance.
Explanatory information:
Explanatory information:
The intent of requiring the barrier to have a high resistance to damage during construction is to increase the barrier’s ability to resist punctures during construction. By being less susceptible to puncturing, the barrier will provide increased protection against moisture containing dissolved salts from coming into contact with the concrete slab.
P2.2.4 Drainage from swimming pools
A swimming pool must have adequate means of draining the pool in a manner which will not—
(a)
cause illness to people; or
(b)
affect other property.
Note:
Note:
The Housing Provisions do not contain any Deemed-to-Satisfy Provisions for this Performance Requirement.
State and Territory Variations
State and Territory Variations
P2.2.4 does not apply in the Northern Territory.
Verification Methods
V2.2.1 Weatherproofing
(a)
Compliance with P2.2.2 for the weatherproofing of an external wall that—
(i)
has a risk score of 20 or less, when the sum of all risk factor scores are determined in accordance with Table V2.2.1a; and
(ii)
is not subjected to an ultimate limit state wind pressure of more than 2.5 kPa; and
(iii)
includes only windows that comply with AS 2047,
is verified when a prototype passes the procedure described below:
(iv)
The test specimen is in accordance with the requirements of (b).
(v)
The test procedure is in accordance with the requirements of (c).
(vi)
The test specimen does not fail the criteria in (d).
(vii)
The test is recorded in accordance with the requirements of (e).
Table V2.2.1a – Risk factors and scores
|
Risk factor |
Category |
Risk severity |
Score |
|
Wind region |
Region A (AS/NZS 1170.2) |
Low to medium |
0 |
|
Region B (AS/NZS 1170.2) |
|||
|
Region C (AS/NZS 1170.2) |
High |
1 |
|
|
Region D (AS/NZS 1170.2) |
Very high |
2 |
|
|
Number of storeys |
One storey |
Low |
0 |
|
Two storeys in part |
Medium |
1 |
|
|
Two storeys |
High |
2 |
|
|
More than two storeys |
Very high |
4 |
|
|
Roof/wall junctions |
Roof-to-wall junctions fully protected |
Low |
0 |
|
Roof-to-wall junctions partially exposed |
Medium |
1 |
|
|
Roof-to-wall junctions fully exposed |
High |
3 |
|
|
Roof elements finishing within the boundaries formed by the external walls |
Very high |
5 |
|
|
Eaves width |
Greater than 600 mm for single storey |
Low |
0 |
|
451-600 mm for single storey; or |
Medium |
1 |
|
|
greater than 600 mm for two storey |
|||
|
101-450 mm for single storey; or |
High |
2 |
|
|
451-600 mm for two storey; or |
|||
|
greater than 600 mm for above two storey |
|||
|
0-100 mm for single storey; or |
Very high |
5 |
|
|
0-450 mm for two storey; or |
|||
|
less than 600 mm for above two storey |
|||
|
Envelope complexity |
Simple shape with single cladding type |
Low |
0 |
|
Complex shape with no more than two cladding types |
Medium |
1 |
|
|
Complex shape with more than two cladding types |
High |
3 |
|
|
As for high risk but with fully exposed roof-to-wall junctions |
Very high |
6 |
|
|
Decks, porches and balconies |
None; or |
Low |
0 |
|
timber slat deck or porch at ground level |
|||
|
Fully covered in plan view by roof; or |
Medium |
2 |
|
|
timber slat deck attached at first or second floor level |
|||
|
Balcony exposed in plan view at first floor level; or |
High |
4 |
|
|
balcony cantilevered at first floor level |
|||
|
Balcony exposed in plan view at second floor level or above; or |
Very high |
6 |
|
|
balcony cantilevered at second floor level or above |
Notes to Table V2.2.1a :
- Eaves width is measured horizontally from the external face of any wall cladding to the outer edge of any overhang, including fascia and external gutters.
- Barriers to prevent falling and parapets are considered as 0 mm eaves.
(b)
Test specimen
The test specimen must incorporate—
(i)
representative samples of openings and joints, including—
(A)
vertical and horizontal control joints; and
(B)
wall junctions; and
(C)
windows or doors; and
(D)
electrical boxes; and
(E)
balcony drainage and parapet flashings; and
(F)
footer and header termination systems; and
(ii)
for a cavity wall—
(A)
a transparent material for a proportion of the internal wall lining (to provide an unobstructed view of the external wall cladding) with sufficient structural capability and similar air tightness to resist the applied wind pressures; and
(B)
a 15 mm diameter hole in the internal wall lining below a window.
(c)
Test procedure
(i)
The test procedure for a direct fix cladding wall or unique wall must be as follows:
(A)
Apply 100% positive and negative serviceability wind pressures to the external face of the test specimen for a period of not less than 1 minute each.
(B)
Apply static pressure of either 300 Pa or 30% serviceability wind pressure, whichever is higher, in accordance with the water penetration test procedure at clause 8.5.2 of AS/NZS 4284.
(C)
Apply cyclic pressure in accordance with—
(aa)
the three stages of Table V2.2.1b; and
(bb)
the water penetration test procedure at clause 8.6.2 of AS/NZS 4284.
Table V2.2.1b
|
Stage number |
Serviceability wind pressure |
|
1 |
15% to 30% |
|
2 |
20% to 40% |
|
3 |
30% to 60% |
(ii)
The test procedure for a cavity wall must be as follows:
(A)
Apply 100% positive and negative serviceability wind pressures to the external face of the test specimen for a period of not less than 1 minute each.
(B)
Apply static pressure of either 300 Pa or 30% serviceability wind pressure, whichever is higher, in accordance with the water penetration test procedure at clause 8.5.2 of AS/NZS 4284.
(C)
Apply cyclic pressure in accordance with—
(aa)
stage 3 of Table V2.2.1b; and
(bb)
the water penetration test procedure at clause 8.6.2 of AS/NZS 4284.
(D)
To simulate the failure of the primary weather-defence or sealing, the following procedure must be applied to the test specimen:
(aa)
Insert 6 mm diameter holes through the external face of the cavity wall in all places specified below:
(AA)
Wall/window or wall/door junctions at ¾ height.
(BB)
Immediately above the head flashing.
(CC)
Through external sealing of the horizontal and vertical joints.
(cc)
Within 30 minutes of the completion of (bb), remove the internal lining of the cavity wall and check for compliance with (d).
(dd)
With the internal lining removed, apply a final static pressure test at 50 Pa for a period of 15 minutes.
(d)
Compliance
(i)
A direct fix cladding wall and unique wall are verified for compliance with P2.2.2 if there is no presence of water on the inside surface of the facade.
(ii)
A cavity wall is verified for compliance with P2.2.2 if there is no presence of water on the removed surface of the cavity, except that during the simulation of the failure of the primary weather-defence or sealing, water may—
(A)
transfer to the removed surface of the cavity due to the introduced defects (6 mm holes); and
(B)
contact, but not pool on, battens and other cavity surfaces.
(e)
Test report
The test report must include the following information:
(i)
Name and address of the person supervising the test.
(ii)
Test report number.
(iii)
Date of the test.
(iv)
Cladding manufacturer's name and address.
(v)
Construction details of the test specimen, including a description, and drawings and details of the components, showing modifications, if any.
(vi)
Test sequence with the pressures used in all tests.
(vii)
For each of the static and cyclic pressure tests, full details of all leakages, including position, extent and timing.
Explanatory information:
Explanatory information:
Verification Method V2.2.1 contains the same test procedures, compliance criteria and reporting of test results that are contained in Verification Method FV1, Volume One of the BCA. Consequently, the Guide to Volume One of the BCA contains detailed and supportive explanatory information that is also relevant to V2.2.1.