Can helping hand brackets & insulation be fixed to sheathing board?
- Read time: 1.5 minutes
- Date: 13 Mar 2024
- Rainscreen & Façades
A rainscreen façade is normally supported using a metal substructure system, manufactured from aluminium or steel. This substructure is often built from components including L-shaped brackets (known as helping hand brackets) and rails.
The helping hand brackets are usually fixed into the backing wall or through the backing wall into the substructure, depending on the wall build-up. The rainscreen panels are fixed to the rails. This structure creates a cavity, typically between 60mm and 600mm deep, which contains the insulation and an air gap.
When working on façade projects, always consult suitably qualified professionals to ensure that it is correctly designed and calculated.
How is a backing wall constructed?
A backing wall can be made from a variety of materials including:
Structural Insulated Panels (SIPs)
Steel framing system (Steel studs & sheathing or backing boards)
Masonry and concrete
Composite carrier panel
Can you fix helping hand brackets to SIPs?
Structural Insulated Panels (SIPs) are a type of composite sandwich panel used to construct the external walls or roof of a building. SIPs have a core made from rigid foam insulation which is sandwiched between two layers of structural board, such as 11mm or 18mm OSB facing.
It is generally permissible to use helping hand brackets with SIPs, but always check the panel manufacturer's guidance as there may be a requirement to fix additional softwood battens into the panels to achieve sufficient pull-out values.
What are sheathing (building) boards in steel framing systems made from?
Sheathing boards, also known as building boards, are available in a variety of different materials that are usually non-combustible with A1 or A2 Euroclass reaction to fire classification. Examples include:
Fibre Cement
Cement-bonded Particleboard
Calcium Silicate
Gypsum
Magnesium Oxide
It's important to note that it is common for the names to be abbreviated, replaced, or used incorrectly. For example, when someone refers to 'Cement Board' they could mean Cement-bonded Particleboard or Fibre Cement board. To avoid errors, the contractor must check to ensure they are using the correct type of sheathing board for the project.
Sheathing board manufacturers should also be consulted to ensure their products are suitable for use in the specific application.
Can you fix helping hand brackets to sheathing (building) boards in steel framing systems?
Fixfast façade calculations do not accommodate fixing helping hand rail and bracket systems into these types of building boards because the fastener pull-out values are inconsistent due to variations such as the nature and thickness of the material, moisture content, etc.
As a result, helping hand brackets and load bearing rainscreen substructure must be fixed into the steel framing system behind the sheathing board.
Other manufacturer's advice may vary so always check with your chosen fastener manufacturer.
Can you fix insulation to sheathing (building) boards?
It is generally accepted that insulation can be fixed directly to certain types of sheathing boards if it is not possible to fix it to the support structure. Always seek approval on this fixing method from both the building board and the insulation manufacturers as well as the appropriate authorising body e.g.: NHBC Technical, before starting construction.
Insulation manufacturers may have their own minimum fixing patterns. To determine the fixing pattern, you will need to give the following information to your chosen fixing supplier:
Sheathing board manufacturer and type
Sheathing board thickness
Insulation type
Insulation thickness
Insulation manufacturer's minimum fixing pattern
Project location
Whether there is a fire safety requirement*
*Fixfast will always assume there is a fire safety requirement unless advised otherwise, but other manufacturers may take a different approach.
