Rubber soul

How to get perfect watertight rubber seals on roof tiles and flashing

A secure rubber seal is critical to avoiding a leaky roof! Learn to prep and apply rubber sealant to your roofing tiles or flashing with the help of this guide. Keep your home dry year-round, start today!

The many uses of rubber roof sealant

Specialized rubber roof sealant is the best product for sealing around gaps and joints at chimneys, sky lights, flashing, for some roofing tiles and for covering nails. It’s designed to fill connections and joints, and provides a strong, flexible watertight seal that secures your home from extreme weather and temperatures. 

Best rubber sealant for exteriors

For the best professional grade sealant that provides durable UV resistant seals, reach for Loctite PL Roof And Flashing Polyurethane Sealant. This black rubber-like sealant repairs and seals flashing around roof edges and chimneys. Its non-sag elastic formula remains flexible and will not crack. The sealant is also paintable and has a low VOC. 

Compatible materials for Loctite PL Roof And Flashing Polyurethane Sealant:

  • asphalt
  • aluminum
  • fiberglass
  • metal
  • brick
  • wood 
  • concrete
  • stucco and more

How to prep different surfaces for rubber roof caulk

For a flawless finish, it’s important to begin with the right conditions and correct surface preparation. The best temperature range for using rubber caulk is above 40 degrees F. Surfaces must be clean, dry and free of any loose material that might compromise proper adhesion.

Here’s how to prepare metal, masonry and wood for rubber sealant.


All masonry must be cleaned with a wire bristle and ground down to expose a surface free of contamination. If joints have absorbed oils, the area of concrete needs to be removed. Concrete needs to be fully cured before sealing.


Scale rust and other coatings until bright metal is exposed. Remove protective coverings and chemical residue with a solvent.

Wood (painted and unpainted):

Weathered, treated and dry rotted surfaces need to be cut away and cleaned. Scrape away paint to expose bare wood. The rubber seal can be repainted after it cures.

Joint Preparation: The depth of the sealant joint must be ½ the width of the joint. Max joint depth is ½” (13mm). Minimum joint depth is ¼” (6mm). The maximum joint width is 1.5 inches (38mm). Closed-cell backer rods or expansion joint fillers can be used for filling deeper joints.

How to use rubber sealant on roof tiles 

If you’re replacing a couple of roof tiles or if you need to cover and protect roofing nails, synthetic rubber caulk will do the trick. 

Always take adequate safety precautions when performing any roofing projects! 

  1. Remove old tiles.
  2. Clean any debris from the roof or tiles with a toothbrush or wire brush. 
  3. Pre-fit the new tiles to make sure everything fits as it should. 
  4. Load the sealant into the caulking gun and cut the nozzle to size.
  5. Apply a bead of Loctite PL Roof And Flashing Polyurethane Sealant along the top edge of the down slope tile. 
  6. Press the new upslope tile against the bead and hold firmly.
  7. Continue securing the tiles according to the manufacturer’s instructions until the project is complete. 

Dry tooling on nails or along exposed sealant joints can be done within the first 5 minutes after application. Use clean mineral solvents if necessary. Avoid soapy water, it may cause discoloration.

How to apply rubber sealant on window, vent pipe, and other flashing

Replace old flashing in a flash! All you need for this simple fix is a new precut piece of flashing, rubber sealant, new tiles or shingles for the area, a nail gun and safety equipment.

Here’s how to replace an old piece of flashing:

  1. Remove the old flashing and clean the area thoroughly.
  2. Pre-fit the flashing to ensure a good fit between the flashing and the structure.
  3. Apply a bead of rubber adhesive sealant in and along the corner joints.
  4. Press the flashing piece into the sealant.
  5. Continue securing the flashing into place according to the manufacturer’s instructions.
  6. Cover the surrounding flashing area with roofing tiles or shingles if necessary.

Your flashing may require an additional waterproof rubber seal around the edges, always check with the a roofing specialist if you have any questions.