Torch-on felt roofing has come a long way since the traditional ‘pour and roll’ systems. Many of these would dry out with age and sun damage, offering a low life expectancy. As a result, manufacturers have made sure roofing solutions keep up with the times. So, today’s products are easier, safer and more cost effective than using a hot bitumen pot to roll out regular felt.

Torch-on bitumen felt roof system technology includes SBS and APP-modified torch-applied roofing systems. SPS is generally easier to install as it requires less heat. The felts are sold as a roll and applied using a blow torch, which melts the back of the felt onto the surface. Systems are available in a wide choice of colours to best suit a project.

Let’s take a closer look at the essentials you’ll need when felting your roof.

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IKO torch on felt roofingWhat is the best torch-on roofing felt system?

To assess the best torch-on felt roofing system, you would need to be able to compare systems on an identical project over a period of time. Whilst we don’t have that information, we do recommend using a proven product from a leading manufacturer. Roofing Superstore’s best-selling torch-on felt solution is made by roofing specialists IKO.

How do I apply a torch-on felt roofing system for optimum results?

When applying a roofing felt torch, our experts recommend a three-layer system. This follows guidelines which contribute to guarantees. A key factor is the three-layer system can optimise the life expectancy of the roof. To summarise, the system comprises the following:

1. Venting layer – perforated underlay

Firstly, you will need to remove debris from the area where the product is to be applied. Once this is done, using a nail gun, place this layer as a starter for the three-layer system. The use of perforations means this can allow for better ventilation.

2. Underlay – 2mm

The torch-on felt underlay layer bonds to the venting layer and comes finished with sand on the top. With this in mind, it should be cut to size to suit the measurements of the roof for a neater finish.

3. Mineral cap sheet – 4mm

This layer is the final touch! It comes in a wide variety of colours to suit various properties. In addition to this, it secures that much-needed durability when combined with the rest of the layers. Typically being able to protect from UV rays and periods of wet weather.

How long will the flat roof felt last? 

The general consensus is that this particular style of roofing can last up to a decade. However, according to some roofing professionals, this can be extended depending on how well it is maintained in the upcoming years. 

Having said this, the maintenance level required for this type of roofing is low. In effect, this means you can save on costs with repairs and similar upkeep costs when it comes to keeping the roof updated. 

What torch-on roof solutions should I choose?

IKO SBS TorchThe IKO Ruberoid SBS Turbo Torch has the added advantage over other torch-on felt products, as the modified bitumen melts faster for quicker application. It also then cools faster to peak bonding strength, reducing any footmarks or potential slumping. Using our gas torch kit with this IKO felt will give you the best results, guaranteeing high performance and longevity.

As an alternative, Roofing Superstore’s own brand SBS Fast Torch Plus torch-on felt offers fantastic value and excellent performance. The reinforced felt increases the waterproofing capabilities of this product, plus it’s both rot-proof and has high elasticity for use in awkward dimensions. We recommend using our gas torch kit, as it’s compatible with both felt options.

How much felt do I need to use on my roof?

One of the simplest ways to calculate how much you need is by finding out the measurements of the roof first. The easiest way to do this is by measuring the roof in meters squared. If you’re working with roofs of different complexities, these will require you to obtain more torch-on felt to cover the surface area.

How much does it cost to felt a roof?

The total cost of refelting your roof depends on multiple factors. The most important are the size of your roof, its age and condition and where you live.

To give you a general idea, the average cost of felt roofing is about £30 – £45 per square metre. For example, the cost of roof felt for a medium-sized shed is around £250 – £450. Refelting an average flat roof garage will set you back anywhere between £1,000 and £2,000. While it is possible to buy cheap roofing felt, we would advise against it, as it probably won’t last very long.

Don’t forget you also need to take into account the price of labour, which stands at around £200 per day. To get the best deal, always make sure you shop around and get quotes from multiple local roofers in your area.

What are the safety regulations for torch-on felt roofing?

Applying torch-on felt involves a naked flame and materials melted at high temperatures. This is a hazardous job; as such it requires high-level safety measures. Applications must conform to UK Building Regulations.

Make sure you complete the project in accordance with the relevant Codes of Practice and British Standards (including BS 8747:2007, BS 8217:2005, BS6229:2003, and BS 5250:2011 – correct at the time of publishing). For anyone considering a project of this nature without the necessary skill set, safety precautions or insurance cover, we recommend contacting a professional.


Adding torch-on felt to your flat roof is a smart investment. The best torch on felt will provide a waterproof moisture barrier and prevent structural damage to your roof, thereby ensuring its longevity. 

Want to find out more about the different types of roofing felt? Head over to our Roofing felt buyer’s guide!

For more information on these products, contact our friendly, helpful team of advisers on 01752 692 760. Alternatively, use the live chat function in the bottom right-hand corner of our website!

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