Caps, Chase Covers and Dampers on Murray Roofs

Two kinds of chimney stand on roofs in this city, and they need different hardware. Knowing which one you have changes what you should be asking for.

Metal chases and the cover on top

A framed chase clad in siding with a factory-built fireplace inside is common on homes built here from the eighties onward. The top is closed off with a metal chase cover, and a great many of those covers were originally made from galvanized steel and formed nearly flat.

Flat is the problem. Snow settles on the valley floor and sits rather than blowing off, and meltwater ponds in the low spots on the cover instead of running off. Standing water on galvanized steel finds the seams and the fastener holes, rust starts underneath, and eventually the cover perforates. Water then runs straight down inside the chase onto the firebox and the framing, and it usually shows up as a stain on a ceiling well before anyone thinks about the chimney. The replacement to ask for is stainless steel, cross-broken so it drains, with a proper drip edge and a collar sealed to the flue pipe.

Caps on masonry chimneys

An open masonry flue takes rain and snow melt directly onto the smoke shelf and the damper, which is what rusts dampers solid and what carries soot and moisture down into the firebox. A stainless mesh cap with a lid stops water, stops birds nesting in the spring, and keeps the flue dry through the months nothing is burning. It is inexpensive, it is bolted or clamped to the flue tile, and it prevents several of the repairs we are otherwise called out for.

Dampers that actually close

The original throat damper in an older Murray fireplace is a warped cast plate that has not sealed properly in decades. Replacing it in the throat means masonry work. Fitting a top-sealing damper at the flue top instead gives a gasketed seal, keeps the whole flue dry when it is closed, and stops the constant loss of heated air. On a fireplace used a handful of times a winter, that seal is doing far more work than the fireplace is.

Waterproofing brick, in the right order

Repointing and crown repair come first. Only then does a breathable water repellent make sense, and it has to be one that lets vapor out rather than sealing the surface with a film. Trapping moisture inside brick before a freeze is how a waterproofing job makes things worse.