Bitumen Felt is a flexible bituminous roofing and waterproofing material used across roof decks, sheds, garages, underlays, flat roofs, and selected construction applications.
Its water-resistant bituminous layer can provide reliable moisture protection when the correct product is combined with proper roof design and installation.
However, not every Bitumen Felt product is the same.
Carrier type, reinforcement, thickness, surface finish, exposure rating, installation method, roof pitch, overlaps, flashing, drainage, and maintenance all influence performance.
Professional buyers should therefore select Bitumen Felt according to the actual roofing or waterproofing specification rather than relying only on the generic product name.
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Bitumen Felt is a flexible roll material used primarily for roofing and waterproofing applications. It generally consists of a supporting carrier or reinforcement that is impregnated or coated with bituminous material to create a moisture-resistant sheet.
Bituminous felt has long been associated with roof construction, roof underlays, sheds, garages, waterproofing details, and selected building applications.
Depending on the product, Bitumen Felt may be installed as an underlay beneath another roofing material, used as part of a multi-layer waterproofing system, or serve as the primary weather-resistant covering on suitable structures.
Modern products can vary significantly from traditional roofing felt. Some use cellulose-type carriers, while others may incorporate fiberglass, polyester, or polymer-modified bituminous compounds.
For this reason, buyers should not assume that every roll sold as Bitumen Felt has the same strength, thickness, reinforcement, temperature resistance, or installation method.
Quick Answer: What Is Bitumen Felt?
Bitumen Felt is a flexible roofing or waterproofing sheet made by combining a supporting carrier with bituminous material to provide a water-resistant membrane.
It is commonly used on roofs, sheds, garages, roof decks, waterproofing details, and selected construction surfaces.
Exact composition, thickness, reinforcement, and installation method depend on the specific product.
Table of Contents
- What Is Bitumen Felt?
- What Is Bitumen Felt Made From?
- How Does Bitumen Felt Work?
- Main Types of Bitumen Felt
- Bitumen Felt for Roofing
- Bitumen Felt for Flat Roofs
- Bitumen Felt for Sheds
- Bitumen Felt as Roofing Underlay
- Bitumen Felt for Waterproofing
- Main Benefits
- Bitumen Felt vs Roofing Felt
- Bitumen Felt vs Modified Bitumen Membrane
- Bitumen Felt vs Bitumen Roof Paint
- Bitumen Felt vs Corrugated Bitumen
- Installation Basics
- Common Problems
- How to Choose Bitumen Felt
- FAQs
What Is Bitumen Felt?
Bitumen Felt belongs to the wider family of bituminous sheet waterproofing materials.
Rather than applying liquid bitumen directly onto a roof, the bituminous material is incorporated into a preformed flexible roll.
The roll can then be installed over a suitable roof deck or other prepared substrate.
A Bitumen Felt system may provide:
- Moisture resistance
- Roof underlay protection
- Waterproofing
- Secondary weather protection
- Temporary or permanent roof covering depending on product
- Protection beneath other roofing layers
The actual role depends on how the product has been designed.
Some lightweight roofing felts are primarily used as underlays, while heavier reinforced membranes can form part of more substantial waterproofing systems.
What Is Bitumen Felt Made From?
Traditional and modern Bitumen Felt products can use different constructions.
A typical system may contain:
Carrier or Reinforcement
Possible carrier materials can include:
- Cellulose-type felt
- Fiberglass
- Polyester
- Composite reinforcement
Bituminous Material
The carrier may be:
- Impregnated with bitumen
- Coated with bitumen
- Surrounded by a thicker bituminous compound
Surface Finish
Depending on product design, the surface may include:
- Mineral finish
- Sand
- Protective film
- Release film
- Other surface treatment
Modern waterproofing membranes may also contain polymer-modified bitumen, such as SBS- or APP-modified systems.
The exact construction should always be confirmed from the product Technical Data Sheet.
How Does Bitumen Felt Work?
Bitumen naturally resists water.
When incorporated into a continuous sheet, it creates a barrier that helps stop water from reaching the substrate beneath.
A properly installed Bitumen Felt roof depends on several factors working together.
Continuous Membrane
The sheet provides the primary moisture-resistant layer.
Correct Overlaps
Adjacent sheets overlap so water cannot easily pass between them.
Sound Roof Deck
The membrane requires a suitable supporting substrate.
Proper Flashing
Edges, walls, drains, chimneys, and penetrations need careful detailing.
Correct Fixing or Adhesion
Depending on the product, the membrane may be:
- Mechanically fixed
- Bonded
- Self-adhered
- Torch applied
- Installed using another specified method
A good membrane can still leak if joints or penetrations are poorly installed.
Main Types of Bitumen Felt
Traditional Roofing Felt
Traditional roofing felt generally uses a felt-type carrier treated with bituminous material.
It has been widely used for:
- Roof underlay
- Sheds
- Garages
- Utility buildings
- Secondary waterproofing
Reinforced Bitumen Felt
Reinforcement can improve dimensional stability and mechanical strength.
Possible reinforcements include fiberglass or polyester.
Mineral-Surfaced Bitumen Felt
Some felts have mineral granules or another exposed finish.
These products may be designed for exposed roofing applications depending on specification.
Self-Adhesive Bitumen Felt
Self-adhered membranes incorporate an adhesive surface protected by release film.
They can be installed without conventional torch application where the product is designed for that method.
Polymer-Modified Bitumen Felt
Some modern membranes use polymer-modified bitumen.
SBS or APP modification may be incorporated to alter flexibility, temperature behavior, or other characteristics.
These products are often more accurately described as modified bituminous membranes rather than traditional roofing felt.
Bitumen Felt for Roofing
Roofing is the main application associated with Bitumen Felt.
It can be used on suitable:
- Flat roofs
- Low-slope roofs
- Shed roofs
- Garage roofs
- Roof decks
- Outbuildings
- Utility structures
- Selected commercial roofs
Its function can vary.
In one system, the felt may be only an underlay.
In another, multiple felt layers may create the principal waterproofing system.
The roof design should therefore specify exactly what role the Bitumen Felt performs.
Bitumen Felt for Flat Roofs
Flat and low-slope roofs require careful waterproofing because water drains more slowly than on steeply pitched roofs.
Bituminous membranes can be used to create continuous waterproofing across the roof deck.
Important areas include:
- Roof drains
- Parapets
- Upstands
- Wall junctions
- Roof penetrations
- Seams
- Edges
A flat roof should also be designed with adequate falls and drainage.
Bitumen Felt should not be expected to compensate permanently for severe standing water caused by poor roof geometry.
Bitumen Felt for Sheds
Bitumen Felt for sheds is one of the best-known applications.
Shed roofs often use relatively simple timber roof decks that can accept lightweight roll roofing materials.
A typical shed-roof installation may involve:
Timber Roof Deck → Bitumen Felt → Overlaps → Fixing/Adhesion → Edge Detailing
Performance depends on:
- Roof pitch
- Deck condition
- Felt type
- Fasteners or adhesive
- Overlap
- Wind exposure
- Edge detailing
Thin lightweight shed felt should not automatically be assumed suitable for larger commercial or permanent building roofs.
Bitumen Felt as Roofing Underlay
Bitumen Felt can also serve as an underlay beneath another roof covering.
The underlay provides secondary protection if water passes through or beneath the outer roofing layer.
It may also contribute to temporary weather protection during construction.
Possible outer roof materials can include certain:
- Tiles
- Shingles
- Slates
- Roofing panels
However, modern roofing systems may also use synthetic underlays.
Selection should follow the roof specification rather than assuming Bitumen Felt is required in every system.
Bitumen Felt for Waterproofing
Although roofing is the main association, bituminous sheet materials can also be relevant to other waterproofing applications.
Depending on the product, uses may include:
- Foundations
- Walls
- Concrete decks
- Below-ground structures
- Damp-proofing details
- Construction transitions
For below-ground structures, the membrane may need mechanical protection before backfilling.
The complete system can include:
Prepared Surface → Primer → Bituminous Membrane → Protection Board → Drainage → Backfill
Critical structures should follow an engineered waterproofing specification.
Benefits of Bitumen Felt
Water Resistance
Bituminous materials provide strong resistance to water penetration.
Preformed Thickness
A factory-produced sheet provides more consistent material thickness than a hand-applied liquid coating.
Flexible Roofing Format
Roll materials can cover large roof surfaces efficiently.
Wide Range of Applications
Different products can serve roofs, underlays, sheds, waterproofing, and construction details.
Repairability
Localized damage can sometimes be repaired using compatible bituminous materials.
Established Roofing Technology
Bituminous roll roofing has a long history in building waterproofing.
Multiple Installation Options
Depending on the product, systems may use:
- Mechanical fixing
- Adhesive
- Self-adhesion
- Torch application
Bitumen Felt vs Roofing Felt
In everyday use, Bitumen Felt and Roofing Felt are often used interchangeably.
However, “roofing felt” is broader.
Some modern roof underlays may not be bitumen-based at all.
Therefore:
Bitumen Felt → specifically bituminous roll/felt material
Roofing Felt → broad roofing-underlay term that may include bituminous or other technologies
For SEO, natural variations such as Bitumen Roofing Felt and Bituminous Felt should be included throughout the article.
Bitumen Felt vs Modified Bitumen Membrane
Traditional Bitumen Felt and modern Modified Bitumen Membranes are related but not identical.
Feature | Bitumen Felt | Modified Bitumen Membrane |
Binder | Bituminous | Polymer-modified bituminous |
Carrier | Felt/fiberglass/etc. | Often reinforced |
SBS/APP | Not necessarily | Common |
Roofing Use | Common | Common |
Waterproofing | Common | Strong specialized use |
Mechanical Strength | Product dependent | Often engineered for demanding systems |
Temperature Performance | Product dependent | Modification can broaden performance |
Installation | Product dependent | Torch/self-adhered/etc. |
A modern SBS membrane should not simply be described as ordinary traditional felt if its technical construction is substantially different.
Bitumen Felt vs Bitumen Roof Paint
These products have different forms and applications.
Bitumen Felt
A preformed flexible roll membrane.
Bitumen Roof Paint
A liquid-applied coating.
Feature | Bitumen Felt | Bitumen Roof Paint |
Form | Roll/sheet | Liquid |
Thickness | Factory controlled | Application controlled |
Seams | Requires overlaps | Generally seamless |
Large Roof Areas | Common | Product dependent |
Local Details | Requires cutting/detailing | Very adaptable |
Structural Roof Covering | Product dependent | No |
Maintenance | Repairable | Often used for maintenance |
In some roof systems, liquid coatings may be used for details or maintenance around existing felt.
Bitumen Felt vs Corrugated Bitumen
These two terms should not be confused.
Bitumen Felt is a flexible roll sheet.
Corrugated Bitumen is a profiled roofing sheet.
Feature | Bitumen Felt | Corrugated Bitumen |
Form | Flexible roll | Corrugated sheet |
Support | Usually continuous deck | Battens/purlins/deck as designed |
Roof Type | Flat/low slope common | Pitched roofing |
Installation | Bonding/fixing/torch etc. | Mechanical fixing |
Drainage | Roof falls | Corrugations + roof pitch |
This difference is useful for both buyers and SEO structure.
Bitumen Felt vs Bitumen Band
Bitumen Felt generally covers larger areas.
Bitumen Band is usually a narrower strip used around:
- Joints
- Flashing
- Membrane transitions
- Penetrations
- Local repairs
A Bitumen Band may sometimes be used to reinforce a detail within a larger felt or membrane system.
How to Install Bitumen Felt
Exact installation depends on the specific product.
A general process may include:
Step 1 — Inspect the Roof Deck
The substrate should be stable, clean, and suitable.
Step 2 — Prepare the Surface
Remove:
- Dust
- Loose material
- Sharp projections
- Oil
- Standing water where prohibited
Step 3 — Apply Primer if Required
Some bonded or torch-applied systems require a compatible primer.
Step 4 — Plan Sheet Layout
Arrange rolls so water flows over overlaps rather than against them.
Step 5 — Install the First Layer
Use the specified mechanical, adhesive, self-adhered, or heat-applied method.
Step 6 — Form Correct Overlaps
Side and end overlaps should match the product instructions.
Step 7 — Detail Edges and Penetrations
Pay particular attention to:
- Parapets
- Drains
- Pipes
- Roof edges
- Upstands
- Corners
Step 8 — Inspect the Finished Membrane
Look for:
- Open seams
- Wrinkles
- Blisters
- Poor adhesion
- Damage
- Inadequate detailing
Exact overlap widths, temperatures, primer requirements, and fixing intervals must come from the relevant installation guide.
Torch-On Bitumen Felt
Some bituminous roofing membranes are installed using controlled heat.
The lower surface is heated sufficiently to bond the membrane to the prepared substrate or previous membrane layer.
Torch installation requires skilled personnel because improper heating can damage the membrane or create significant fire hazards.
Torch-applied products should only be installed according to the relevant system specification and site safety requirements.
Cold-applied or self-adhesive alternatives may be used where specified.
Self-Adhesive Bitumen Felt
Self-adhesive membranes use a factory-applied adhesive layer.
Installation generally involves removing a release film and carefully bonding the material onto a suitable prepared substrate.
Advantages can include avoiding open-flame installation in applications where the selected product is appropriate.
However, adhesion can be affected by:
- Dust
- Low temperatures
- Moisture
- Poor surface preparation
- Inadequate pressure
Self-adhesive does not mean surface preparation can be skipped.
Common Bitumen Felt Problems
Open Seams
Poorly bonded overlaps can allow water entry.
Blistering
Trapped air, vapor, or moisture can contribute to blister formation.
Wrinkling
Poor installation or movement can produce wrinkles.
Mechanical Damage
Foot traffic, tools, sharp objects, or later construction work can puncture the membrane.
Poor Flashing
Water often enters around penetrations and edges rather than through the middle of a sound sheet.
UV Exposure
Some products are intended to be covered, while others have surfaces designed for exposure.
Do not leave an underlay-grade membrane exposed unless its specification permits it.
Poor Drainage
Standing water can place unnecessary stress on a roofing system.
Can Bitumen Felt Be Repaired?
Localized damage can sometimes be repaired using a compatible bituminous patch, membrane section, band, or sealing material.
The repair area should first be inspected to determine:
- Cause of damage
- Extent of deterioration
- Condition of surrounding felt
- Moisture beneath the membrane
If the roofing felt is widely deteriorated, repeated patching may not be the most appropriate long-term solution.
A larger overlay or replacement system may be required.
How Long Does Bitumen Felt Last?
There is no universal lifespan for Bitumen Felt.
Service life depends on:
- Product grade
- Reinforcement
- Membrane thickness
- Exposure
- UV protection
- Installation quality
- Roof drainage
- Climate
- Maintenance
- Mechanical damage
Lightweight shed felt and heavy reinforced roofing membrane should not be expected to have identical service lives.
Any exact longevity or warranty claim should come from the specific product documentation.
Is Bitumen Felt Waterproof?
Bitumen Felt is intended to provide strong moisture resistance and, in suitable systems, waterproofing.
However, complete roof waterproofing depends on the entire installation.
Even high-quality material can leak because of:
- Incorrect overlaps
- Poor flashing
- Failed penetrations
- Mechanical damage
- Inadequate drainage
So performance should be evaluated as a roofing system, not simply a roll of material.
How to Choose Bitumen Felt
Professional buyers should consider:
Intended Use
Underlay, exposed roof covering, shed roof, or structural waterproofing?
Carrier
Felt, fiberglass, polyester, or other reinforcement?
Thickness
Check the product specification.
Surface Finish
Will the membrane remain exposed or be covered?
Roof Type
Flat, low slope, or pitched?
Installation Method
Mechanical, adhesive, self-adhesive, or torch applied?
Movement and Temperature
Will the roof experience significant movement or temperature cycling?
Fire Requirements
Confirm applicable roof-system requirements.
Technical Documentation
For commercial procurement, request:
- TDS
- SDS where applicable
- Installation instructions
- Dimensions
- Thickness
- Reinforcement
- Surface finish
- Exposure suitability
- Storage requirements
Bitumen Felt and SHM Trade Global
SHM Trade Global operates as a Global Importer, Supplier & Exporter of Bitumen Products & Industrial Materials.
Bitumen Felt is closely related to the broader roofing and waterproofing sector, but Bitumen Felt is not currently confirmed as a separately stocked SHM Trade Global core product.
For this reason, the website article should remain educational and should not claim guaranteed inventory.
Professional buyers can provide their required:
- Membrane specification
- Thickness
- Reinforcement
- Roll dimensions
- Application
- Quantity
- Destination
to confirm current sourcing or availability.
Frequently Asked Questions About Bitumen Felt
What is Bitumen Felt?
Bitumen Felt is a flexible roll roofing or waterproofing material made by combining a supporting carrier with bituminous material.
What is Bitumen Felt used for?
It is commonly used for roofing, roof underlay, sheds, garages, waterproofing, and selected construction applications.
Is Bitumen Felt waterproof?
Suitable Bitumen Felt can form part of a waterproof roof system, but overall performance depends on overlaps, flashing, installation, drainage, and membrane condition.
Is Bitumen Felt the same as Roofing Felt?
The terms are often used interchangeably, although roofing felt is a broader term and some modern roof underlays are not bitumen-based.
Can Bitumen Felt be used on flat roofs?
Yes, suitable bituminous membranes are commonly associated with flat and low-slope roofs when properly specified and installed.
What is the difference between Bitumen Felt and Modified Bitumen?
Traditional Bitumen Felt is a broad roll-roofing material, while modified bitumen products use polymers such as SBS or APP to alter selected performance characteristics.
Can Bitumen Felt be used on a shed roof?
Yes. Lightweight bituminous roofing felt is widely used on suitable shed roof decks.
Does Bitumen Felt need heat during installation?
Not always. Some products are mechanically fixed or self-adhesive, while others are torch-applied. Installation depends on the specific membrane.