Local chimney chase cover replacement for Atlantic Beach homes

Measuring over the finished siding

The framing inside a chase is built to a size, but the chase you see from the roof is larger by the thickness of its sheathing, siding and trim. Lap siding adds a stepped profile, and corner boards stand out further still. A cover made to the framing dimensions will sit inside the siding instead of over it, and water will run straight into the joint. So the four sides are measured at the top over the finished surface, the diagonals are checked for square, and the skirt is sized to clear the thickest point with room to fasten.

Folded, welded and sealed seams

One-piece chase tops have seams only at their corners, where the skirt folds down. A very large chase, or one with an unusual shape, may need two sheets joined across the top.

Every seam is a possible leak, and fireplace manuals call for caulking all seams on the chase top. Corner seams are folded so water runs over them rather than into them. Joints across the top are folded and locked or welded, then sealed, and placed where water runs across them rather than along them. Fewer seams in the flat means fewer places to fail, which is why we cut one sheet where the chase size allows.

Screws through the skirt sides

Every screw that goes through the flat of a chase top is a hole in the part of the cover where water runs. Installation steps for these chimneys fasten the top through its sides instead.

We drive the fasteners through the skirt into the chase framing, below the joint the skirt protects, spaced closely enough to hold the edge flat in wind. The screws are in a metal compatible with the cover, with sealing washers where the maker calls for them. The flat of the new top stays unbroken except for the pipe collars, and the old screw holes in the framing are filled so the new screws bite fresh wood.