Local chimney cap replacement in Avondale

Hood height and the draft it leaves

The gap between the top of the flue tile and the underside of the cap's hood is the path smoke takes out of the chimney. Too small a gap throttles the flow; too large a gap lets rain blow in under the hood. Cap makers publish the hood height for each model and size, and BIA's residential chimney note advises getting the maker's information on how a cap affects gas flow before choosing one.

We set the cap so the tile top sits within the range the maker gives, measured rather than judged by eye. That measurement is recorded, so if the draft ever changes, the first thing to check is already written down.

A flue serving a furnace or water heater

When a masonry flue carries exhaust from a heating appliance or water heater, that appliance's installation instructions govern the vent, including what may sit on top of it. Those instructions can call for a particular cap type or rule out a fine screen, because mesh on an appliance flue can collect debris and restrict the exhaust. We identify the appliance on each flue before choosing a cap, follow its instructions, and record which cap went on which flue. If the appliance vents through its own metal pipe running inside the chimney, that pipe stays with the termination its own maker specifies, and we leave it as it is.

Two caps or one cover for side-by-side flues

Two tiles standing next to each other can each take a single-flue cap, provided there is room for both hoods and both tiles stand clear of the crown. One outside-mount cover over both is the alternative. Separate caps keep each flue independent, so servicing one does not disturb the other, and they need less metal. One cover shields more of the crown and puts no fasteners into the tiles, but it needs sound concrete to anchor into. We measure the spacing between tiles and their heights before recommending either, and when both would work, you see the two priced side by side.