Roofing felt is crucial in protecting your roof and ensuring its longevity. Various types of felt roofing are available for both pitched and flat roofs. Choosing the proper flat roof felt can be daunting with a wide range of options available in the market.
This blog post will cover flat roof felt. Flat roof felt is suitable for flat roofs. We will discuss its purpose, options available, materials made from, advantages, lifespan and more.
What is the purpose of roofing felt?
Roofing felt is crucial in constructing and protecting roofs. This thin, flexible material plays a vital role in safeguarding the integrity of the roof and the structure it covers.
- Prevents water infiltration and protects against water damage, rot, and mould growth
- Channels water away from vulnerable areas like joints, valleys, and roof penetrations
- Allows trapped moisture or vapour to escape, reducing condensation and moisture buildup
- Maintains a dry and healthy environment, minimising the potential for rot, mould, and mildew
- Shields the roof from wind-driven rain, snow, and ice
- Creates a protective barrier against extreme weather events
- Enhances the longevity and durability of the roof by reducing wear and tear
- Protects against maintenance-related damage
- Some types offer insulation properties, improving energy efficiency
- It provides sound dampening, reducing noise transmission from the outside environment.
Exploring Different Roofing Felt Options
There are three types of roofing felt used for flat roofing projects. These are: Torch-on felt, Self-adhesive felt, shed felt
Each type has advantages and considerations, depending on the installation method and the project size.
Torch-on felt
Torch-on felt is a popular choice for flat roofs as it provides a reliable and quick installation. It involves melting three layers of bitumen felt onto the roof using a blowtorch to create a waterproof seal.
Typically, these layers consist of a vapour control sheet, reinforced felt, and a cap sheet with a mineral finish. It is important to note that building regulations may require three layers for habitable areas. Sheds and garages, however, may only need two layers.
However, the torch-on method can be hazardous and should be done by experienced roofers due to open flames.
The cost of hiring an expert to install a single garage is typically between £750 and £850.
The lifespan of a torch-on-felt roof is around 15 to 25 years.
Shed Felt
Shed felt is specifically designed for sheds and garden buildings. It is available in torch-on and self-adhesive applications and offers an aesthetically pleasing finish that complements landscaped gardens.
Although sheds and garden buildings may not be frequently considered for re-roofing, shed felt provides a weatherproof and waterproof solution.
Flat roof trims
Flat roof trims, edge trims or roof edgings are essential components for flat roofs. They provide a clean and finished look while protecting the roof edges. These trims help to prevent water infiltration and ensure proper drainage.
Common flat roof trims include drip edges and fascia trims. Drip edges direct water away from the roof. Fascia trims cover and protects the fascia board.
Corner trims and termination bars create clean and secure edges at corners and terminations. Flat roof trims play a crucial role in maintaining the integrity and longevity of flat roofs.
What is roofing felt made from?
Roofing felt is typically made from a combination of organic or synthetic materials.
Organic roofing felt is made from cellulose fibres, often from recycled paper or wood pulp. It is then saturated with bitumen, a petroleum-based waterproofing material.
On the other hand, a synthetic flat roof felt is made from polyester or fibreglass fibres coated with bitumen. This coating provides waterproofing properties to protect the roof deck and underlying structure.
Some roofing felts may also have additional additives or treatments to enhance their durability, UV, and fire resistance.
What are the advantages of felt roofing?
Roofing felt is commonly used in the construction industry as an additional layer of protection beneath the roofing shingles or tiles.
Here are some of the benefits of using flat roof felt:
Moisture Barrier
A flat roof felt is a moisture barrier, preventing water from seeping through the roof deck and damaging the underlying structure. It helps protect the roof from leaks caused by rain, snow, or ice.
Improved Weather Resistance
A felt roof enhances the roof's resistance to various weather conditions by providing an extra layer of protection. It helps to guard against wind-driven rain, snow, and ice dams.
Heat and Cold Insulation
Roofing felt offers some degree of insulation, helping to regulate temperature extremes. Thermal barriers can help control the internal temperature of a building. In the summer, they can prevent excessive heat gain. In the winter, they can help retain heat inside.
Enhanced Roof Longevity
Installing roofing felt can extend the roof's lifespan by shielding it from potential damage. Minimising wear and tear is helpful. For example, it can reduce the expansion and contraction of the roof deck due to temperature changes.
Added Protection during Roof Installation
A flat roof felt is a temporary protective layer during the roof installation. The roof deck is shielded from potential damage caused by construction activities. This includes walking or accidentally dropping tools.
Improved Aesthetics
Some types of roofing felt have a smooth and uniform surface, providing a visually appealing appearance from below. It can create a neat and professional look for the underside of the roof.
Easy Installation
Roofing felt is relatively easy to install and can be applied quickly. It comes in rolls that can be easily cut to fit the roof's dimensions, making it a convenient choice for roofing
contractors.
How long does the roof felt last?
The lifespan of a flat roof felt varies depending on several factors. These include the felt used, the climate in which it is installed, and how well it is maintained. In general, roof felt can last anywhere from 10 to 30 years.
JJ Roofing Supplies stocks a selection of roofing felt from top-notch manufacturers. These felt come with warranties for flat roofs.
When should the roof felt be replaced?
Roof felt could deteriorate over time due to various factors. Here are some signs that may indicate it's time to replace flat roof felt:
Age
Roof felt has a limited lifespan. If your flat roof felt is nearing or has exceeded its expected lifespan, it's a good idea to consider replacing it. The lifespan can vary depending on the type of material used, but generally, it can last between 15 to 30 years.
Visible damage
Inspect the flat roof felt for any visible signs of damage, such as tears, cracks, or curling at the edges. It may be time for a replacement if you notice significant damage in multiple areas.
Leaks
If your roof leaks, it could be a sign that the flat roof felt worn out. This means it is no longer stopping water from getting in. Leaks should be addressed promptly to avoid further damage to your home's roof structure and interior.
Roofing project
Are you planning a significant roofing project, such as a complete roof replacement? Replacing the flat roof felt is expected as part of the process. This ensures that all roofing system components are updated and work together effectively.
How much felt will I need for my roof?
Choosing the right roofing felt for your home is critical. It can have a significant effect on your roof's performance and durability. Here are some key factors to consider when selecting roofing felt:
- Consider factors like material (organic or synthetic), weight, and thickness for durability. Water resistance is essential to prevent moisture-related damage.
- Opt for breathable options to prevent condensation.
- Ensure compatibility with your roofing material and check local building codes.
- Look for a warranty. Seeking advice from professionals can provide valuable insights.
- Remember, proper installation techniques are equally important for an effective roofing system.
Measure the correct roofing felt for your space. To do this, follow these instructions to determine which flat roof felt would be right for you.
- Measure the length and width of your roof to get the total square footage.
- Multiply the length by the width to calculate the actual square footage of your roof.
- Divide the actual square footage by the coverage per roll to determine the number of rolls needed.
This is just a rough estimate. It is best to consult a professional or refer to the product's packaging for more accurate calculations. This way, you can ensure you use the right product for your needs.
Do you nail or glue roof felt?
Roofing felt or underlayment is typically attached to the roof deck using nails. Nailing provides a secure and reliable method of installation that ensures the felt remains in place during the roofing process.
The most common approach is roofing nails with large heads, such as galvanised ones. Pins used for felt usually range from 1 to 1.5 inches long. They have a broad head to stop them from slipping through the material.
Install roofing felt by nailing along the edges and seams. Nail at regular intervals throughout the material. It is important to consult local building codes or manufacturer recommendations for specific instructions on the exact spacing of the pins.
Nailing is the standard way to attach a flat roof felt. However, there are times when adhesives or self-adhesive roofing underlayment can be used instead.
Adhesives or self-adhesive materials are often used when nailing is impossible or not allowed.
However, nailing is the preferred method for securing roofing felt for most residential roofing applications.
Conclusion
In conclusion, "Flat Roof Felt Buyer's Handbook" is a comprehensive guide for individuals purchasing flat roof felt.
This handbook equips you with the knowledge necessary to make informed decisions. It covers various topics, such as the purpose of flat roof felt, types of materials, and advantages. Additionally, it provides guidance on how to choose the right roofing felt.
Contact us for a bespoke quote for your next roofing project.
