A new chimney chase cover, measured and installed in Riverview

Slope that moves rain off the cover

A chase cover should not be a flat sheet. The same manufacturer's manual calls for the chase top to slope downward, away from the pipe opening, and gives a minimum pitch of a quarter inch per foot for its system. Water that runs off quickly has less time to work on seams and fasteners.

When a cover sags or was installed flat, water collects in the middle and around the collar. We measure the chase and order a cover shaped to drain toward the edges, then check the finished pitch after it is fastened. A cover that sheds water also stays cleaner of leaves and grit.

When a chase cover can be repaired instead

Not every leaking chase cover needs replacing. A cover in sound metal with one open seam, a loose fastener or a storm collar that has slipped can often be repaired, and the estimate shows that smaller repair when it fits.

Replacement makes sense when the metal is rusted through in several places, when the cover holds water across its surface or when it was never shaped to drain. Patching those covers tends to buy a short time before the next leak.

• Repair: one failed seam, loose fasteners or a slipped storm collar on sound metal
• Replace: rust holes, a dished surface or an opening with no raised collar
• Look further: soft framing, wet insulation or stains well below the top

Looking after a new chase cover

Once the new cover is in place, a look from the ground after heavy storms is usually enough. Watch for a cover that has shifted, new rust marks on the siding or water where it did not appear before. Keeping branches trimmed back from the chase stops leaves piling up on the cover.

Do not climb up to adjust the cover or the storm collar. If something looks wrong, call and describe it. NFPA safety guidance recommends having chimneys inspected every year, and the chase top is part of that check.

Chase covers on stucco-finished chases

Where a chase is finished in stucco rather than siding, the skirt of the cover laps over the stucco at the top edge. Cracks, stains or soft areas in the stucco just below the cover can be a sign that water has been getting behind the finish.

We check how the old skirt sat on the stucco and whether the top edge of the finish is sound before measuring. Stucco repair is separate work and appears on its own line, and the new cover is sized so its drip edge carries water clear of the stucco face.