How to Choose Between EPDM and Felt for Your Flat Roof

Neither EPDM nor felt is the best choice for every flat roof; suitability depends on the roof’s condition, layout, drainage and the specific system and installation proposed. Because felt covers different products and methods, have the existing roof assessed and compare quotations for preparation, substrate repairs, insulation, detailing and exclusions.

Neither EPDM nor felt is automatically the better choice for every flat roof. The right option depends on the roof’s condition, shape, substrate, drainage and detailing, as well as the specific product and installation method proposed. “Felt” covers several types of system, so ask for the actual system to be identified and compare the full scope of work, not just the material name. If the roof is already leaking, arrange an assessment rather than choosing a replacement covering based on the symptom alone.

Table of Contents

Which is better for a flat roof: EPDM or felt?

There is no universal winner. A suitable EPDM membrane may work well for one roof, while a specified felt system may be more appropriate for another. The decision should account for the condition of the roof, its layout and edges, the substrate beneath the covering, drainage, and how joints and penetrations will be finished.

Product specification and installation matter as much as the broad material category. A quote that says only “rubber” or “felt” does not give enough detail to compare the proposed work. A photograph or a single symptom cannot establish which system suits the roof, or whether the roof needs a new covering at all.

  • Compare named systems and installation methods, rather than generic material labels.
  • Check how the proposal deals with the deck, insulation, outlets, edges and other details.
  • Ask what assessment supports the recommendation and what is excluded from the work.

What do EPDM and felt roofing involve?

EPDM is a synthetic rubber membrane used as a flat-roof covering. Felt roofing generally uses bituminous sheets, which are installed as part of a system. Both need suitable preparation and carefully formed details at roof edges, upstands, outlets, rooflights and other penetrations.

These coverings are not simply interchangeable sheets. Each flat-roof system has its own products, joints and installation requirements. The quotation should name the product or system and explain how it is to be applied.

What does “felt roofing” mean?

“Felt” can refer to different products and methods. Depending on the system, sheets may be torch-applied, self-adhesive or installed using a cold-applied method. Not every felt system is torch-applied, and the application method affects how the work is carried out. Where heat is involved, ask how the contractor will manage relevant fire-safety considerations.

EPDM sheets and felt sheets both require joints or laps and edge detailing. The number and position of joints depend on the product, roof dimensions and layout. Neither material should be assumed to be seamless, maintenance-free or leak-proof. Ask for product information and installation details relevant to the system being quoted.

How do EPDM and felt compare on the factors that matter?

Use the same questions for each proposal. The details below are product-dependent, so a contractor should explain how the specific system will be built up and finished on your roof.

Factors to compare when considering EPDM and felt
Factor EPDM system Felt system What to confirm
Construction Usually a membrane-based covering; the exact build-up and fixing method depend on the system. Typically made up of bituminous sheets or layers; the specified number and type depend on the product. Ask for the named system, product details and proposed roof build-up.
Joints and edges Sheet joints, perimeters and penetrations need compatible detailing. Joint layout depends on the roof and sheet arrangement. Laps, edges and penetrations need to be formed to suit the specified product and application method. Ask how the edges, upstands, outlets and rooflights will be finished.
Roof layout Sheet sizes and the shape of the roof can affect joint positions and detailing. Roof shape and details can affect how sheets and layers are laid and joined. Check that the contractor has considered the roof’s dimensions and awkward junctions.
Substrate and insulation Suitability depends on the condition of the deck and the proposed system build-up. Suitability also depends on the deck, preparation and proposed build-up. Ask what will be inspected, retained, repaired or replaced, and whether insulation is included.
Repairs and maintenance Repair requirements depend on the product, damage and surrounding details. Repair requirements depend on the product, damage and surrounding details. Ask how a future defect would be assessed and which product-specific repair method applies.
Performance information Service life, fire performance, maintenance and warranty terms vary by product and conditions. Service life, fire performance, maintenance and warranty terms vary by product and conditions. Check the named system’s technical documents and the exact terms provided with the quote.

Do not rely on broad claims about lifespan, repair cost or maintenance frequency without documentation for the product being offered. A warranty is useful to understand, but it does not by itself show that the system is suitable for the roof.

What features of your roof should guide the choice?

The roof itself can make a general EPDM-versus-felt comparison misleading. Before accepting a recommendation, consider what is known about these features and ask the contractor to explain anything that needs closer assessment.

  • Existing covering and deck: A leak or damaged surface may have more than one cause. The covering, deck or insulation may need further assessment before a replacement system is specified.
  • Shape and details: Roof dimensions, perimeter edges, upstands, adjoining walls, outlets and rooflights affect the work and the detailing required.
  • Drainage: Ask how rainwater is intended to reach the outlets. Visible ponding may warrant professional assessment, but it does not by itself prove the cause or show that the entire roof must be replaced.
  • Use and access: Tell the contractor if the roof needs routine access for maintenance, or if it serves an occupied home, rental property, garage or business premises.
  • Installation constraints: Discuss access to the roof and the proposed application method. Ask how any relevant safety considerations will be managed.

Keep observations to what you can see safely from inside or from ground level. Do not climb onto the roof or an unsafe ladder to inspect it or take photographs. If a ceiling is bulging, materials are falling, water is near electrical fittings, or there are signs of structural movement, keep people away and seek appropriate urgent assistance.

Should you repair the existing roof or replace it?

A material comparison is useful only after considering whether the existing roof is suitable for repair, an overlay or replacement. A local defect may be repairable, but a leak, the roof’s apparent age or a photograph alone cannot confirm the right scope of work.

  1. Describe the concern. Note where water appears, when it happens, and whether there are visible changes from a safe position.
  2. Arrange an assessment. The roof and, where necessary, underlying materials may need professional inspection. Maxwell’s offers roof inspections to help assess roof concerns.
  3. Clarify the options. Ask what evidence supports repair, overlay or replacement, and whether hidden moisture or damage could affect the recommendation.
  4. Agree how changes will be handled. Before work starts, ask what happens if deterioration is found after the covering is removed, and how any additional work would be discussed.

An overlay should not be assumed suitable without checking the existing roof’s condition, moisture, substrate and the requirements of the proposed system. If replacement is recommended, ask for the scope and build-up in writing and compare the flat-roof replacement options on that basis.

What should you compare in EPDM and felt quotations?

Compare the specified work and supporting information, not only the headline material or total price. Use this table to record what each contractor has included. If an item is unclear or marked as excluded, ask for an explanation before deciding.

Flat-roof quotation comparison checklist
Item to compare EPDM proposal Felt proposal
Exact product or system
Installation method and proposed roof build-up
Removal of existing covering or proposed overlay
Substrate inspection and possible repairs
Insulation and other build-up details
Edges, upstands, outlets and penetrations
Drainage considerations
Access and safety arrangements
Preparation, waste removal and exclusions
Product documents and any warranty or guarantee terms
How concealed or unexpected defects will be handled

This checklist is for comparing proposals, not a technical inspection or a substitute for a site-specific assessment. Ask for the relevant product documentation and clarification of any warranty or guarantee, including what it covers and any stated conditions. If two quotations differ substantially, check whether they include the same preparation, materials and details before comparing their totals.

Discussing your flat roof in Milton Keynes

If you are weighing up EPDM and felt for a garage, extension or another flat roof in Milton Keynes or a nearby area, Maxwell’s Roofing And Property Maintenance can discuss the concern and the proposed scope. Call 07311 091804, email sa***@*****************ng.uk, or request a free, no-obligation quotation.

It helps to provide the property location, the roof type and approximate size if known, whether it is a new or existing roof, the symptoms or work you are considering, and details of previous repairs. You can include photographs taken safely from ground level, but do not climb onto the roof to take them.