Watertight flat roofs: a hot air welding buyers guide

Watertight flat roofs: Hot Air Welding Buyers Guide

One of the most effective methods for achieving a watertight seal on flat roofs without naked flame is hot air welding. As the name suggests, this technique uses hot air to fuse roofing membranes together, creating strong, durable seams. In this buyers’ guide, we will explore everything you need to know about hot air welding for flat roofing projects.

What is hot air welding?

Hot air welding is a process that uses high-temperature air to join roofing membranes. Using temperatures up to 600°C, hot air melts the surfaces of the membranes. These are then pressed together with a manual roller or by the welding machine to form a strong, seamless bond.

Hot air welding is widely used in the roofing industry due to its efficiency and reliability. As the process provides a uniform and consistent bond, the risk of leaks and failures are greatly reduced. It can also be undertaken by one operative, making it more efficient that other alternatives.

Being a flameless method, hot air welding is also a safer option for many jobs. And as it creates seamless, watertight bonds without the use of solvents or chemicals, hot air welding is the preferred choice for many roofing professionals who are looking for more environmentally friendly solutions.

Why hot air welding? 

Hot air welding creates strong, durable seams that can withstand harsh weather conditions, UV exposure, and mechanical stress. The bonds ensure a long-lasting, watertight roof with lower maintenance costs over the lifespan of the roof.

The process itself is quick and efficient, reducing installation time, labour costs, and project turnaround times. It is also an extremely versatile solution. As well as being suitable for use with a wide range of materials, hot air welding is ideal for complex roof designs, ensuring effective sealing on roofs that might prove challenging for other methods.

Tools for hot air welding 

It goes without saying, no hot air welding job can be completed without hot air welding equipment. When choosing a supplier, it pays to look for a one-stop-shop that can supply everything you’ll need, from the heat gun and accessories to the flat roof materials.

 Essential hot air welding tools include:

• Hot air equipment: with a wide array of hot air tools and equipment available it is important to have the right solution for the job. You can read more about the key factors to consider when choosing equipment in the next section of this article.
• Nozzles: attachments that direct the hot air onto the membranes. Different nozzles are designed for different types of scenarios and details
• Pressure rollers: tools used to press the membranes together after heating. Rollers come in various sizes and materials to suit different membrane types and welding conditions.
• Roofing membranes include TPO, PVC, and Bituminous membranes. Each type of membrane has unique properties, requiring specific temperature and pressure settings for optimal results. Consider your roofing membrane alongside your hot air welding machine – they are not all compatible.

It can pay to consider investing in a hot air welding kit, which includes everything you need to do the job (apart from the membrane!) in a handy case – including the tool itself, along with essential accessories such as rollers, cutters, nozzles and brushes.

How to select the right hot air welding machine 

Before starting the job, it is important to choose the right hot air welding machine. Things to consider include:

• Power and temperature control

Finding the perfect temperature for the application can depend on the type of material, its thickness and the environmental conditions. Look for a machine with adjustable power and temperature settings, which allow you to tailor the heat output to the specific type of roofing membrane you are working with. Precise control ensures that you can achieve the perfect weld without damaging the membrane. Advanced machines often feature digital displays and programmable settings, making it easier to maintain consistent welding conditions.   These features also mean machines can be used in different settings, improving the return on investment.

• Portability and ease of use

Consider the weight and design of the machine. A portable and user-friendly machine will make the welding process more manageable, especially for large roofing projects. Lightweight machines with ergonomic designs and intuitive controls can enhance user comfort, while semi-automatic machines can also help reduce operator fatigue. Look for machines with features like comfortable handles, clear displays, and straightforward adjustment mechanisms.

It also pays to think about power sources and availability. Products such as the BAK LiiOn Hot Air Battery Welding Tool, for example, can operate without the need for electricity on site. Instead, it comes complete with a battery, a charger and the welding tool, all stored in a handy backpack and is ideal for snagging or repairs.

• Brand and warranty

Reputable brands such as BAK offer high-quality hot air welding machines with reliable performance. A good warranty can provide peace of mind and protect your investment. Customer reviews and industry recommendations can also be valuable resources when selecting a brand. Opt for manufacturers known for their durability, innovation, and customer service. Also ensure your supplier can support you with repairs or temporary hire of replacement equipment when needed so you can keep working.

Ready to get started? Speak to our team for help specifying the right hot air welding kit for your next flat roof project or check out our range of BAK hot air welding equipment on our Lancastria website.