Hot Melt Roofing Guide: When To Use Hot Liquid Roof Systems

When considering a new roof for your domestic or commercial property, there are a number of things to take into account. This includes the local weather conditions, the style of the property and the longevity of the roofing materials.

Two popular roofing choices are single ply roofs and hot melt roofing and this is especially true for commercial roofing. While both offer distinct benefits, there are instances when you would opt for hot melt roofs.

This article explores what hot melt roofing is, what the benefits are and applications. Let’s look at each in turn…

Hot Melt Roofing
Hot Melt Roofing – SPS Roofing Ltd

What is Hot Melt Roofing?

Hot melt is a waterproofing membrane that can be applied to flat roofs. When covered, it becomes part of the waterproof barrier without creating a dome over the surface. It’s the perfect waterproofing solution for flat roofs that are used as living spaces.

They are generally easy to install and last much longer than other membranes. Some of the common use cases include inverted roofs, green roofs, podium decks and substructure waterproofing.

This roofing option uses a two layer bituminous rubber system with an approximate depth of 6mm, with reinforced fleece between the layers, and a fully bonded felt layer over the top. This option is easy to use for bonding with concrete, timber, brickwork and other materials, ensuring surface irregularities are concealed.

Benefits of hot melt roofing

Long lasting

Hot melt roofing is the ideal choice for any commercial or industrial building owner who requires a roofing that will last over the property’s lifetime. They are well known for its durability and gives you peace of mind knowing your roof will last multiple decades.


A hot melt roofing system creates a truly monolithic waterproof barrier, seamless with no laps or joints. It’s therefore a great choice for a 100 percent waterproofing system. These properties combined with the convenience of installing it, will ensure that your roofing provides exceptional protection for your building.

Cost effective

Though the installation of the hot melt roof may require more capital, the long benefits of it can definitely outweigh providing a positive return on your investment. It’s designed to withstand the harshest winters, and can be installed to zero falls at -18°C. It’s easy to install, and requires little/no maintenance during the lifetime of the building.


Hot melt roofing is the perfect choice for any property with a large roof. It resists standing water, dilute acids or fertilisers that would damage ordinary roofing systems. This is great because it ensures a long useful life making it a viable investment. It also comes with a weatherproof protective layer that lasts without the need for ongoing maintenance or replacement.

Use cases for hot melt roofing

Is hot melt roofing the best choice of flat roofing system? Are hot melting roofing popular? These are probably some of the questions you may have in mind right now. At SPS Roofing, we provide the ideal solution for waterproofing your roof and hot melt roofing is one of the best choices for it.

As such, there are several use cases and let’s explore them in more detail.

  1. Designing a green roof

Green roofs have grown in popularity over the past recent years and we generally recommend hot melt roofs for a green roof design. Not only will you appreciate its long life and durability, but it’s also one of the simplest waterproofing systems to install.

It’s also important to note that the green roof should be designed to be at least the equivalent of the minimum ballast weight of an Inverted Roof System.

  1. Waterproofing a concrete deck

Hot melt is a modern waterproof solution ideal for trouble-free waterproofing of concrete decks, from small residential properties right up to large scale commercial projects. It’s quick to install and requires no drilling into concrete or vapour barrier membranes. Compared to other waterproofing methods, hot melt has a wide use in a broad range of applications and it’s the best choice for fast, cost effective DIY projects.

  1. Installing a flat roof

Flat roofs are becoming a popular choice for modern homeowners due to their design versatility. Having a fall on a flat roof is essential in the event of rainfall or snowfall. Without a fall, water can accumulate and create flooding, which will damage everything in your home.

These falls need to be in place as part of complying with the codes of practice and BBA certification (minimum finished fall of 1:80). This is essential for waterproofing as most flat roofing would require a fall. However, with a hot melt roof, the deck can be completely flat as long as certain conditions are met. This can come in handy especially when planning considerations restrict building heights.

  1. Fast Track Flat Roofing

Hot melt roofing systems spread smoothly and self level, allowing for faster installations. This helps to reduce cost overruns, which is especially helpful for fast-track construction projects . Hot melt systems can also be installed at temperatures as low as -18 Celsius: a big plus since winter weather can make construction impossible.

  1. Save cost on Insulation, Falls and Maintenance of Flat Roofs

When installed with hot melt technology, tapered insulation and screeds are not needed. This is because hot melt is formulated to last the lifetime of the building on which it is installed. As such, you can save costs on maintenance making it a very cost effective solution. This is useful in situations when you are on a tight budget.

  1. Complex roof layouts 

In case of a complex flat roof layout with slopes and penetrations, a hot melt can simplify your new flat roof installation. If you need to install HVAC equipment or have several penetrations, this roofing system can cut costs and speed up the process.

In addition to removing the need to design in falls, hot melt roofing can be simply detailed to allow for a wide variety of upstands, penetrations and structural connections. This will not only improve its functionality but also the aesthetics of the flat roofing structure.

  1. Designing a Flat Roof for a Long Life

A hot melt adhesive applies the membrane to the deck without thermal damage. Water is unable to penetrate where it’s not supposed to go. Plus, hot melt makes the membrane adhere better to the deck, so if it does become damaged, you can remove it and replace it easily. This makes it easier to undertake repairs and thereby ensure your flat roof lasts much longer.

Factors to consider when installing hot melt roofing

  • Look for certified roofers who have the right expertise to install hot melt roofing. It should be carried with careful consideration to ensure a long lasting flat roof.
  • The roofing deck should be suited to balance the load of an inverted roof system which is usually between 95kg/m2 and 140kg/m2.
  • The roofing contractors you choose should be well aware of the regulations when installing hot melt roofing. Things such as thermal requirements, wind conditions, adequate drainage and overflow need to be factored in to ensure they comply with the recommendations of BS6229:2018.
  • Before installing the insulating and adding the loading coat, the waterproofing system needs to be fully tested to ensure there are no damages. This will ensure there are no leaks, thereby ensuring a longer lifetime for the roof. 

Looking For A Qualified Roofing Company?

SPS Roofing Ltd is a highly rated roofing company based in Exeter operating across Devon and South West England including Somerset, Cornwall, Wiltshire, Gloucestershire and Dorset.