The BHE Façade Specifications for Exterior
Stone Cladding outline the technical requirements for materials,
installation, and design for stone cladding systems used on building exteriors.
While specific BHE Façade Specifications might vary, the general requirements
for minimum and maximum specifications for stone cladding are as
follows:
BHE Façade Specifications - Exterior Stone Cladding Requirements:
|
Specification Category |
Minimum Requirement |
Maximum Requirement |
|
Stone Type |
Durable, weather-resistant stone such as granite,
limestone, marble, sandstone |
High-strength natural stone with enhanced
weathering properties |
|
Compressive Strength of Stone |
2,000 psi (13.8
MPa) |
5,000 psi (34.5
MPa) |
|
Thickness of Stone Panels |
20 mm (0.8
inches) |
50 mm (2
inches) |
|
Panel Size |
300 mm x 300 mm (12 inches x 12 inches) |
1,200 mm x 1,200 mm (48 inches x 48 inches) |
|
Stone Panel Weight |
50 kg (110
lbs) per panel |
100 kg (220
lbs) per panel |
|
Fixing Systems |
Mechanical fixing systems (anchors, clips) |
Mechanical or adhesive
systems, with anchors providing sufficient support based on wind load
calculations |
|
Minimum Anchor Spacing |
600 mm (24
inches) |
900 mm (36
inches) |
|
Joint Width |
6 mm (0.24
inches) |
12 mm (0.47
inches) |
|
Expansion Joints |
Located at 10 m intervals, or as
required by design |
Based on the total length and temperature
changes, typically every 6-8 m |
|
Waterproofing and Drainage |
10 mm drainage
gap behind panels, proper waterproofing membrane behind stone cladding |
Additional drainage provisions depending on
exposure |
|
Fire Resistance |
Class A1
(non-combustible stone) |
Fire-resistance up to 4 hours
depending on the system and thickness |
|
Wind Load Resistance |
Capable of resisting a wind load of 1.5
kN/m² (31.7 psf) |
Capable of resisting wind loads up to 3
kN/m² (63.4 psf) |
|
Tensile Bond Strength |
50 psi (0.34
MPa) for adhesive-bonded systems |
Higher tensile strengths for mechanically
fixed systems |
Key Points and Clarifications:
- Stone Type: The
stone selected for the cladding should be durable, resistant to
weathering, and able to handle external environmental conditions,
especially in coastal or industrial areas. Natural stones like granite,
limestone, and sandstone are common choices.
- Compressive Strength: The
stone should have a minimum compressive strength of 2,000 psi (13.8
MPa) to ensure durability and safety. Some projects may require
higher-strength stone for added performance, particularly in severe
climates or areas with heavy load-bearing requirements.
- Thickness and Weight: Stone
cladding panels are typically between 20 mm to 50 mm thick,
depending on the aesthetic and structural requirements. The weight of the
panels is crucial to ensure the support structure (e.g., anchors and wall)
is designed to bear the load.
- Fixing Systems:
Mechanical fixing systems such as anchors, brackets, or clips are commonly
used to secure the stone panels. Adhesive bonding systems are also
utilized but must meet specific performance criteria.
- Wind Load Resistance:
Depending on the height of the building and the geographical location
(wind zones), stone cladding systems must be able to resist wind
pressures. Minimum requirements typically call for resistance to 1.5
kN/m² (31.7 psf), but higher resistance may be necessary for buildings
in high-wind regions or skyscrapers.
- Fire Resistance: The
stone used in cladding should have a Class A1 fire rating,
indicating that the material is non-combustible. Depending on the
thickness and installation method, the system can provide up to 4 hours
of fire resistance.
- Joint Width and Expansion Joints: The
joint width between stone panels typically ranges from 6 mm to 12 mm
(0.24 inches to 0.47 inches) to allow for thermal expansion and
contraction. Expansion joints should be placed at appropriate intervals
based on the size of the façade, typically at 6-10 meter intervals,
to prevent cracking or movement.
- Waterproofing and Drainage:
Proper waterproofing and drainage systems are essential to prevent water
penetration behind the stone cladding, which could lead to structural
damage. The typical drainage gap behind the panels is 10 mm or more
to allow water to escape.
- Maintenance and Cleaning: Stone
cladding systems should be designed to minimize cleaning requirements. If
cleaning is necessary, it should be possible without damaging the surface
or finish of the stone.
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