While polyurethane does have its strengths related to its fairly low price silicone is by far the superior choice when choosing a chimney sealer.
Caulking for chimney flashing.
Polyurethane has a tendency to break down and has lifespan at best half that of silicone.
Seal the problem seams with roofing caulk using a standard caulk application technique.
Loctite pl s30 polyurethane roof and flashing sealant is a premium quality commercial grade sealant developed especially for forming permanent water and weatherproof seals in all exterior gaps and joints.
Momentarily lift the boot and apply sealant to hold the flashing in.
You can t use too much so get as much as you can in there.
Here is how you do it.
You want to squeeze it into all the nooks and crannies you can.
Put a layer on the edge of each piece of flashing.
Install shingles as normal up to the base of the plumbing vent.
Place a small drop of caulk where the roof and chimney meet at the chimney corner.
Fit an 8 inch 20 3 cm piece of square step flashing over the chimney s front corner.
Set the flashing aside.
Like any other caulking job you want to push the bead not pull it.
Materials required 26 gauge galvanized sheet steel for prefabricated pieces drive in expanding anchors galvanized coil stock galvanized front base flashing galvanized step flashing polyurethane caulk self adhering roofing membrane ice and water barrier.
This sealant is elastic and remains flexible to expand and contract with construction material movement to protect and retain the original.
Installing a roof plumbing vent is typically an easier task than flashing a chimney.
Place the step flashing over the caulk and onto the chimney.
Place the flashing or boot onto the plumbing vent so the base is resting on shingles.
Once each piece of flashing is as secure as it can be apply the silicone caulk.
Effective roof flashing around a chimney includes two layers.
One laying involves tightly playing sheet metal around the chimney edges.
Silicone is an inorganic substance that has high toughness against temperature fluctuations and uv rays.