What a chimney cap installation covers
Installing a cap means measuring the top of each flue, choosing a cap that fits the chimney's size and shape, and fastening it firmly enough that wind can't lift it off. The mesh sides keep birds, squirrels and other animals from building a chimney nest inside the flue. The hood sheds rain and snow before it reaches the liner and damper. The crown and flue top get checked first, so a new cap doesn't go onto damaged masonry. Our chimney cap installation service covers cap styles and materials in more detail.
Evanston's vent-chase rule and what it means for a cap
Evanston's Mechanical Code amendment 801.18.5 lets an abandoned masonry chimney liner serve as a chase for high-efficiency appliance vents beside an active solid-fuel chimney, if that chimney extends 2 feet above the vent and the chase is sealed weather-tight. (Source: City of Evanston, Ordinance 29-O-22, Exhibit F, Title 4 Chapter 6 Mechanical Code, local amendments.)
Who the rule applies to
It applies to masonry chimneys with more than one flue, where one flue still serves a wood-burning fireplace or stove and an old, unused liner beside it now carries the vent pipes for high-efficiency appliances. If your chimney has a single flue, or every flue is active, the rule doesn't come into play.
What it changes about the installation
- Identifying each flue comes first. We confirm which flue is the active solid-fuel chimney and which one is the vent chase before choosing a cap.
- The cap goes on the active flue without blocking or crowding the vent terminations that come out of the chase.
- The chase's weather-tight seal is left intact. A cap that spans the whole chimney top must not open or disturb that seal.
- The 2-foot relationship between the active chimney and the vent stays as it is. The cap is fitted to the existing layout, not used to change it.
Not sure whether your chimney has a vent chase?
If a furnace or water heater was replaced and its venting was rerouted, mention that when you request an estimate. We confirm how the flues are being used from the roof before any cap is chosen.
When a cap is the right job, and when it isn't
- An uncapped flue with rain, debris or animal visits: a new cap is the right job.
- Animals already living in the flue: the nest and any animals come out first, then the cap goes on so they can't return.
- A cracked crown, loose bricks or leaks around the chimney: start with chimney repair for homes in Evanston, because a cap can't seal damaged masonry.
- A prefab chimney topped by a framed chase: the metal chase top may be the real issue. Our guide to chimney cap vs chase cover explains the difference.
- A rusted, bent or loose cap already in place: that is a cap replacement, which we also handle.
Booking cap work in Evanston
Get in touch to request an estimate. Commercial and property-manager work is offered too, so rental and multi-unit buildings can be booked the same way.
For a closer look at how chimney cap installation works, from measuring to fastening, the main service page has the full walkthrough. For the other chimney, fireplace and dryer vent work we do in Evanston, the area page lists every service.
Sources (1)
The sources of the Evanston facts on this page.
- 1City of Evanston - Ordinance 29-O-22, Exhibit F, Title 4 Chapter 6 Mechanical Code (local amendments)
