A1 Stainless Steel Cavity Tray JB SafeSeal

Yes - new regulations within England require most materials and systems used within external walls on relevant buildings to be non-combustible. These regulations were incorporated within the 2018 amendment of the Building Regulations Approved Document B. 

Buildings subject to this legislation rise to 18m or more above ground level, contain one or more dwellings, a room for residential purposes, or an institution. 

Compliant materials must have a fire rating of A1 or A2-s1. 

Cavity trays are used in cavity wall construction, which is a common architectural feature in UK buildings. They are used to collect and redirect any moisture that penetrates the outer leaf of a wall back to the outside of the building, preventing the moisture from crossing into the inner leaf and causing dampness.

Located at key areas within the cavity walls, cavity trays are strategically placed to ensure effective water management and protection against moisture-related issues. These trays are typically placed above the damp-proof course (DPC) level to provide an additional layer of protection against water ingress.

They are also commonly used above window and door openings to intercept and divert any water away from the building, generally through the use of weep holes. Cavity trays can also be found In roof/wall junctions, cavity trays prevent water from collecting in the cavity, causing dampness and eventually structural problems. 

The specific installation of cavity trays is dependent on the design and requirements of each building, ensuring proper integration into the construction process for optimal performance in managing and removing moisture in cavity walls.

To comply with current regulations in England, it is necessary to install a cavity tray system that consists of non-combustible materials and components. These regulations were incorporated in the 2018 amendment of Building Regulations Approved Document B.

The legislation is specified so as to provide non-combustible solutions and systems in building with cavity walls on buildings with a storey of 18 metres or above. Although this may be soon reduced to just 11 meters in height.

The purpose of requiring a non-combustible cavity tray system is to enhance fire safety in high-rise buildings. As cavity trays are embedded within the building envelope and inaccessible for inspection, repair, and maintenance, it is crucial to ensure that they are made from materials that will not contribute to the spread of fire.

This helps protect the integrity of the building and prevent potential damage and harm to the building inhabitants caused by fire penetration through the cavity wall system.

The regulations apply to buildings with dwellings, institutions, or residential rooms, excluding those in hostels, hotels, or boarding houses, but encompassing student housing, care homes, sheltered housing, hospitals, and boarding school dormitories.

The materials utilised in the construction of stainless-steel cavity trays encompass various grades of austenitic stainless steel (specifically grades 304 and 316), which offer exceptional durability and protection against corrosion. 

These grades are commonly chosen for their high levels of chromium and nickel content, providing excellent corrosion resistance. Additionally, grade 316 contains molybdenum, enhancing its resistance to chloride-induced corrosion, and making it suitable for environments with exposure to potential coastal conditions or chloride-rich environments.

Weep holes play a crucial role in preventing water accumulation and sometimes promoting ventilation within cavity walls. These small openings are designed to allow water to escape from the building envelope, effectively reducing the risk of damp/water damage.

Weep holes can be found in various locations such as concrete block walls, brick cavity walls, window frames, By allowing water to escape, they help to alleviate hydrostatic pressure and prevent moisture-related issues.

Additionally, weep holes assist in maintaining a healthy indoor environment by facilitating air circulation and reducing the potential for mould growth. Weep holes are an essential component of effective building design and construction, ensuring the longevity and integrity of the structure by mitigating water-related problems.

Weep holes are an important component of cavity wall construction. They allow water that may have penetrated the outer wall to escape and provide ventilation to the cavity. You will typically find weep holes in the following locations:

Above windows and doors: These are probably the most common places you'll find weep holes. When windows and doors are installed, they interrupt the continuous cavity in the wall, creating a potential point for water penetration. 

To mitigate this risk, a lintel is installed over the window or door to support the masonry above, and a cavity tray is installed above the lintel to catch any water that gets in. The weep holes then allow this water to escape back to the outside.

At the bottom of walls: Weep holes may also be installed at the base of a wall, especially if it's a retaining wall or a wall built into a slope. The idea is to allow any water that's accumulated at the bottom of the cavity to escape.

Where cavity walls meet roofs: Where a cavity wall meets a sloping roof, you may also find weep holes. They are used in combination with cavity trays to prevent water from the roof from seeping into the cavity and reaching the inner wall.

A cavity wall is constructed using a technique that involves the use of two separate skins of construction materials (often referred to as a leaf), an inner and outer leaf, with a cavity between them, that is generally used to contain an insulation material to improve the thermal properties of the building. This type of wall provides various benefits such as improved thermal insulation, dampness prevention, and sound insulation.

The inner leaf is typically constructed of concrete block (either dense or aerated concrete) or a light steel work frame, while the outer leaf generally consists of facing bricks. The two leaves are interconnected by metal ties, which ensure stability and structural integrity. Weep holes are generally incorporated at the bottom of the outer leaf to allow for drainage and sometimes assist with cavity ventilation.

When it comes to fire safety in construction, materials play a crucial role. The A1 Fire Rating is a classification used to determine the combustibility of building products. A material with an A1 rating is considered completely non-combustible and does not contribute to fire at all. This means that it has undergone stringent tests and has demonstrated no potential for fuelling or spreading flames.

The A2 Fire Rating classification is used to assess the limited combustibility of building materials, indicating their ability to contribute minimally to the spread and intensity of fire.

A2 materials have very limited combustibility, making them non-combustible in Scotland and classified as having limited combustibility in England and Wales.

While A1 materials have no contribution to fire, A2 materials have a slightly higher level of contribution. This means that A2-rated building materials are less likely to ignite or burn when exposed to flames or high temperatures compared to other classifications.

The use of A2-rated materials can help enhance fire safety measures in buildings by reducing the risk of fire spreading and minimising potential damage caused by flames.

BBA Certification is a rigorous and comprehensive assessment process provided by the British Board of Agrément (BBA) that thoroughly evaluates and certifies the performance, quality, and compliance of construction products, systems, and installers.

It involves extensive testing, laboratory analysis, and on-site inspections to ensure that the product or system meets the required standards and regulations. The BBA conducts assessments of technical specifications, manufacturing processes, installation procedures, and long-term durability to verify the product's suitability.

Upon successful completion of the assessment, a certificate is issued as evidence of compliance with industry standards. BBA Certification is highly regarded within the construction industry as it provides independent verification of a product's quality and fitness for purpose.

It helps building professionals make informed decisions when selecting construction products by instilling confidence in their performance and compliance with regulations.