Chimney Flashing Repair in West Carson, Built the Way Code Describes

Proper chimney flashing has two layers that overlap like shingles. Step flashing, short L-shaped pieces of metal, is woven into each course of roofing along the sides of the chimney, with one leg on the roof deck and the other turned up against the brick. Counter flashing then covers the top of those step pieces, set into a cut in a mortar joint and bent down over them. Water running down the brick lands on the counter flashing, sheds onto the step flashing and then onto the roof. The two pieces are not fastened together, so the roof and the chimney can move separately. That last point matters in earthquake country, since a rigid seal between a moving roof and a heavy masonry chimney will break.

What we often find instead is a single piece of metal or a bead of roofing cement smeared across the joint between roof and brick. That works for a season or two, then the sun cracks the sealant and the first heavy rain finds the gap. Leaks show up as stains on the ceiling beside the fireplace, damp drywall in an attic, or rot on the rafters next to the chimney. Before we quote a flashing job, we trace the water. A wet ceiling near a chimney can also come from a cracked crown, porous brick or a missing cap, and new flashing will not stop any of those. The written scope names the source we found and the evidence for it, so you are not paying to fix the wrong thing.

The building code adds one more requirement that many older chimneys miss. When a chimney is wider than 30 inches across the slope of the roof, and it does not sit at the ridge, a cricket or saddle is required on the uphill side. A cricket is a small peaked structure that splits the water flowing down the roof and sends it around the chimney instead of letting it pool against the brick. Without one, a wide chimney acts like a dam, and the flashing on the uphill side fails first. Many South Bay ranch houses have wide chimneys built before crickets were common, and adding one during a flashing repair is often the only way to make the fix last.

Roof type changes the details. Composition shingle roofs take standard step flashing. Concrete and clay tile roofs, common on Spanish-style homes from West Carson to Palos Verdes, need flashing shaped to the tile profile and a pan beneath it. Flat or low-slope roofs need a different approach altogether. If you are replacing the roof, the best time to redo chimney flashing is during that job, and we are glad to coordinate with your roofer so the counter flashing is cut into the brick while the step pieces go in. If the roof is in good shape, we replace the flashing without disturbing more roofing than needed. Either way, the scope and price are written before work, and photos show the finished flashing from the roof.