Can EPDM Be Laid Over Existing Roof Coverings?

If you’re considering an EPDM roofing solution, a common question is whether it can be laid directly over an existing roof covering.

The short answer is yes—but only if certain conditions are met. In this guide, we’ll explore the key considerations, benefits, and steps for ensuring a successful installation over existing roofing materials, along with recommended products and best practices.

Quick Answer: Yes, But Assess the Existing Roof First

EPDM can generally be laid over existing roof coverings, such as felt or certain types of asphalt, provided that the existing roof is in good structural condition.

This means the roof must be stable, free of water damage, and relatively smooth to allow proper adhesion.

However, an intermediate layer, such as a vapour barrier or recovery board, may be required for optimal performance.

Factors to Consider Before Laying EPDM Over Existing Roofing

1. Condition of the Existing Roof:

   • The current roof must be stable, dry, and free from cracks or leaks. Any signs of water damage or structural issues should be repaired before applying EPDM.
   • If the roof is in poor condition, it’s often better to remove it to avoid trapping moisture beneath the new EPDM layer.
     
     

2. Suitability of Existing Roofing Material:

   • Some materials are better suited for EPDM overlay than others. Felt and asphalt can work if they’re in good condition, while metal roofing may require special adhesives.
   • Avoid laying EPDM over bitumen or surfaces with loose gravel, as they can compromise adhesion.
     
     

3. Insulation and Vapour Control:

   • Adding a vapour barrier, such as Alutrix 600, can prevent condensation and improve insulation, enhancing the EPDM roof’s performance.
   • If insulation needs upgrading, this is the best time to consider it, as adding insulation after laying EPDM can be challenging.
     
     
     

Benefits of Installing EPDM Over Existing Roof Coverings

Choosing to lay EPDM over an existing roof, when conditions allow, offers several benefits:

• Cost Savings: Skipping a full roof tear-off reduces both labour and disposal costs.
• Environmental Impact: By reusing the existing roof structure, you reduce waste, making it an environmentally friendly option.
• Reduced Installation Time: Laying EPDM directly over the existing roof can streamline the installation process, getting your roof weatherproofed faster.
  
  

Steps for Laying EPDM Over Existing Roof Coverings

Follow these steps to ensure a durable, long-lasting EPDM installation over an existing roof:

1. Thoroughly Inspect and Clean the Surface:

   • Check for any signs of mould, rot, or structural damage. If found, repair these areas to prevent further deterioration.
   • Clean the surface thoroughly to remove dirt, grease, or debris that could interfere with the EPDM’s adhesion.
     
     

2. Apply a Vapour Barrier or Intermediate Layer:

   • Using a product like Alutrix 600 Self-Adhesive Vapour Barrier is recommended, especially if laying EPDM over felt or other porous materials. This layer prevents moisture infiltration and improves adhesion.
     
     

3. Install the EPDM Membrane:

   • Roll out the EPDM membrane and position it over the roof, allowing it to settle.
   • Fold back half of the membrane and apply adhesive to both the membrane and the existing roof surface. For more guidance on choosing the correct adhesive, see our EPDM Roofing Collection.
     
     

4. Seal and Finish:

   • Carefully seal seams and edges to prevent water infiltration. Proper sealing is crucial, especially when installing EPDM over an existing layer, to ensure it remains watertight.
     
     

Frequently Asked Questions About EPDM Roofing Overlays

1. Can I install EPDM over an asphalt roof? Yes, but asphalt must be in sound condition with a smooth surface. Using a vapour barrier can help prevent any issues with adhesion and durability.

2. Do I need a primer for the vapour barrier? A primer may be necessary depending on the condition of the surface. For specific guidance, refer to our guide on using primers with Alutrix 600.

3. How do I handle sloped or pitched roofs? EPDM can be installed on roofs with a slight pitch, but for steeper slopes, refer to our guide on measuring roof pitch to ensure proper installation.

4. Can EPDM be used over an old rubber roof? In some cases, it’s possible to lay EPDM over an existing rubber roof if it’s in excellent condition. However, consult a professional, as double layers of rubber can affect thermal performance and may require special adhesives.

5. Is liquid waterproofing a good alternative? Liquid waterproofing solutions, such as Arboflex Liquid Waterproofing, can be used in areas where EPDM isn’t suitable or for smaller repair jobs on existing roofs.

Recommended Products for a Successful EPDM Installation

For best results, consider these high-quality products to support your EPDM roofing project:

• EPDM Rubber Roofing: A versatile option for reliable, long-lasting waterproofing.
• Alutrix 600 Vapour Barrier: Ideal for adding a protective vapour layer over existing felt or asphalt.
• Resitrix® Partial Bond: A specialised EPDM option offering added durability and partial bond, perfect for renovations.
  
  

Conclusion: Choosing EPDM for Roofing Overlays

In summary, EPDM can be laid over existing roof coverings in many cases, provided the base structure is in sound condition and prepared adequately. The benefits of a cost-effective, eco-friendly roofing solution make EPDM a popular choice for both commercial and residential properties.

Whether you're installing EPDM over an asphalt or felt roof, ensure proper sealing and consider a vapour barrier to maximise durability. For more resources and products tailored to your roofing needs, browse our EPDM roofing collection and related solutions for lasting roof protection.