Fiddler on the roof

How to seal a metal roof that’s leaking: Find and fix leaks fast! 

If you’ve got a leaky roof, check out our guide on how to seal a metal roof. We’ve got an inspection checklist to find the source of the leak, which sealant is best for repairs, and how to repair damaged flashing.

How to seal a metal roof: Areas prone to leaking

Metal roofs take the prize for being the most durable roofing material available. A well cared for metal roof will last decades longer than a wood or tile roof. But even metal needs proper care and sealing to stand the test of time. 

Inspect your roof twice a year for damage and to make sure the sealant is holding. If you’ve already noticed a leak, here’s a list of areas prone to unwelcome water leaks. 

Inspection checklist:

  • trim
  • flashing
  • valleys
  • overlaps 
  • gutters 
  • end laps
  • joints
  • downspouts
  • seams
  • fasteners
  • gaps

How to seal a metal roof: The right sealant for repairing metal roofs

Knowing where to seal your roof is only the first step: knowing which sealant to use is just as important in increasing the longevity of your roof.

Silicone, butyl and polyurethane are the three most common sealants used on roofs; however, they have very different properties that will affect the durability of the seal. Silicone sealants are UV safe, flexible and waterproof. But they are also unpaintable and may crack over time. Butyl sealants harden quickly and are extremely tough but aren’t UV resistant and therefore shouldn’t be used in areas exposed to direct sunlight. 

For sealing small leaks around screws, flashing or other seams and gaps, use Loctite PL Roof And Flashing Polyurethane Sealant. This premium quality polyurethane sealant is especially designed for sealing flashing, shingle tabbing, and covering roofing nails. It’s compatible with most standard substrates, has high UV resistance, low VOC, is paintable and completely weatherproof.  

How to seal a roof leak with polyurethane sealant 

Leaky roofs typically occur around seams, joints, bolts, and, most of all, roof flashing. Here’s how to repair and seal roof flashing that’s damaged and leaking.

Tools

  • wire brush
  • sandpaper
  • Loctite PL Roof And Flashing Polyurethane Sealant
  • cleaning material
  • flashing patch (made of the same material as the flashing) or replacement flashing panel 

How to do it

  1. Inspect the damaged area. If there’s extensive damage to the flashing, remove and replace the panel (see manufacturer’s instructions about joint preparation). Small holes can be patched with polyurethane sealant and/or a small flashing patch.
  2. Using a wire brush, scale away rust and old caulk beads from the affected area to expose the bright metal. Remove any protective coatings, residue or film with a solvent.  
  3. Load the caulk into the gun.
  4. Apply Loctite PL Roof And Flashing Polyurethane Sealant in a steady and consistent stream along the perimeter of the joint or patch. Fill the joints from the bottom up where applicable. 
  5. Attach the patch, covering the damaged area.
  6. Cover any exposed bolts with sealant if necessary.
  7. Dry tool if needed, within the first 5 minutes of application.  
  8. Sealant skins within 24 hours, is functional within 3 days and reaches full cure in 1 week.   
     

Important! If you need to replace rusty bolts, go up one size for a stronger fit.      

Ready to fix the roof?

Here’s where you find our complete range of Polyurethane Sealants for any job under the roof.  
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