In general, it is not recommended to install self-adhered underlayment directly over an existing underlayment. Here’s why:
- Compatibility issues: Different types of underlayment materials may not be compatible with each other, which can lead to problems with adhesion and compromised waterproofing.
- Trapped moisture: Applying new underlayment over an existing layer can potentially trap moisture between the two layers, leading to rot, mold, and further damage to the roof structure.
- Added weight: Adding another layer of underlayment can increase the weight on the roof, potentially exceeding the load-bearing capacity of the structure.
Removing Existing Underlayment
If you want to install self-adhered underlayment and already have an existing underlayment in place, it is generally recommended to remove the old underlayment before proceeding. By removing the old underlayment, you ensure a clean and smooth surface for proper adhesion of the self-adhered underlayment.
Steps to Remove Existing Underlayment:
- Ensure safety: Before starting any roof-related work, ensure proper safety precautions are in place, including using appropriate protective gear.
- Check for damage: Inspect the existing underlayment for any signs of damage, such as tears, cracks, or deterioration. This will help you determine if the underlayment needs to be replaced entirely or just partially.
- Start removal: Begin removing the existing underlayment by gently peeling it away from the roof surface. Take care not to damage the roof deck during this process.
- Clean the roof deck: Once the underlayment is removed, clean the roof deck thoroughly to remove any debris, adhesive residue, or nails. A clean surface will ensure proper adhesion of the self-adhered underlayment.
- Install new self-adhered underlayment: With the roof deck clean and prepared, you can now proceed to install the self-adhered underlayment following the manufacturer’s instructions.
Seeking Professional Assistance
If you are uncertain about the condition of your existing underlayment or unsure of how to proceed with the installation of self-adhered underlayment, it is recommended to consult with a professional roofing contractor. They will have the expertise and knowledge to assess your roof’s specific needs and provide the best solution for your situation.
While self-adhered underlayment offers many benefits for roof protection, it is generally not recommended to install it directly over existing underlayment. Removing the existing underlayment before installing the new self-adhered underlayment ensures proper adhesion, prevents moisture accumulation, and maintains the structural integrity of your roof. Always consult with a professional roofing contractor to ensure the best installation practices and to address any specific issues related to your roof.