Polyurethane has a tendency to break down and has lifespan at best half that of silicone.
Caulking for chimney flashing.
Fit an 8 inch 20 3 cm piece of square step flashing over the chimney s front corner.
Put a layer on the edge of each piece of flashing.
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.
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.
Here is how you do it.
You want to squeeze it into all the nooks and crannies you can.
In the second layer more sheet metal is inserted into the chimney mortar joints and folded over to cover the first layer.
Installing a roof plumbing vent is typically an easier task than flashing a chimney.
You don t have to make it look nice you just need to fully fill the gap.
Momentarily lift the boot and apply sealant to hold the flashing in.
Effective roof flashing around a chimney includes two layers.
Place the step flashing over the caulk and onto the chimney.
Place a small drop of caulk where the roof and chimney meet at the chimney corner.
While polyurethane does have its strengths related to its fairly low price silicone is by far the superior choice when choosing a chimney sealer.
One laying involves tightly playing sheet metal around the chimney edges.
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.
Install shingles as normal up to the base of the plumbing vent.
Getting the right sealant on your flashing is the best bet.
Like any other caulking job you want to push the bead not pull it.
Silicone is an inorganic substance that has high toughness against temperature fluctuations and uv rays.
Set the flashing aside.
