What Is a Rainscreen Sub-Frame System?

Understanding Brackets, Rails and the Structure Behind Modern Façades

Author: FGF Technical

Introduction

A rainscreen sub-frame system forms the structural framework that supports external cladding panels on modern ventilated façades. Although largely hidden once construction is complete, the sub-frame is one of the most important elements of a rainscreen façade, transferring loads safely back to the building while creating the ventilation cavity that allows the façade to perform effectively.

Typically comprising adjustable brackets, aluminium rails and specialist fixings, sub-frame systems are used across commercial, residential, healthcare and education projects throughout the UK.

Selecting the correct support system is essential for structural performance, thermal efficiency and the long-term durability of the façade.

What Is a Rainscreen Sub-Frame?

A rainscreen sub-frame is the structural support system fixed to the primary structure of a building before external cladding panels are installed.

It creates a stable framework that:

• Supports façade panels
• Transfers wind and dead loads
• Maintains the ventilation cavity
• Accommodates construction tolerances
• Supports thermal performance

Once installed, the rainscreen panels are fixed to the sub-frame, creating the completed façade system.

Main Components of a Sub-Frame System

Although systems vary between manufacturers, most rainscreen support systems comprise several key components.

Helping Hand Brackets

Adjustable brackets fixed back to the building structure, providing support for the aluminium rail system while accommodating varying cavity depths.

Aluminium Rails

Vertical or horizontal rails fixed to the brackets to create the structural framework supporting the façade panels.

Thermal Isolation Components

Many systems incorporate thermal isolators or thermal break pads to help reduce heat transfer through the support brackets.

Fixings

Specialist fixings secure the brackets and rails to the building structure while maintaining the structural performance of the façade.

Why Are Sub-Frame Systems Important?

The sub-frame does much more than simply support cladding panels.

Correctly designed systems help:

• Maintain structural stability
• Support the ventilation cavity
• Reduce thermal bridging
• Improve installation accuracy
• Accommodate building movement
• Deliver long-term façade performance

Because every building is different, support systems are typically designed specifically for each project.

Where Are Rainscreen Sub-Frame Systems Used?

Sub-frame systems are widely specified across many sectors, including:

• Commercial offices
• Residential developments
• Education buildings
• Healthcare facilities
• Hotels
• Public buildings
• Façade remediation projects

They are compatible with a wide range of cladding materials, including fibre cement, HPL, aluminium composite, terracotta, porcelain and metal panels.

Design Considerations

Several factors influence the design of a rainscreen support system.

These include:

• Wind loading
• Building height
• Substrate type
• Panel weight
• Cavity depth
• Thermal performance
• Fire performance
• Building movement

Structural calculations should always be carried out in accordance with the manufacturer's design guidance and project requirements.

How FGF Supports Façade Projects

FGF supplies rainscreen support systems from leading manufacturers together with technical guidance for projects throughout the UK.

Our expertise includes:

• Helping hand brackets
• Aluminium rail systems
• Technical specification support
• Product compatibility advice
• Manufacturer guidance
• Nationwide delivery

Working closely with manufacturers and façade contractors, FGF helps ensure the correct support system is specified for every project.

Related Technical Guidance

• Understanding Bracket Spacing, Wind Load & Structural Considerations
• Fixings & Compatibility in Rainscreen Façade Systems
• What Is Rainscreen Cladding?
• Understanding Rainscreen Build-Ups

Need Technical Advice?

Whether you're designing a new rainscreen façade or specifying support systems for a refurbishment project, FGF can provide technical guidance and nationwide supply.

Contact our team to discuss your project requirements.