Signs, Causes, and Fixes for Chimneys Falling Apart
This past week, we looked at an example of a deteriorating chimney which is causing issues that could lead to leakage and or deterioration that could damage a low roof system. Low slope roofs, like all types of roofs, are primarily intended to prevent water and leakage from entering into the building from the exterior.
Here, even though it’s not part of the actual roof system, the chimney essentially has become a weak link in the building shell, at the roof or adjacent to the roof membrane which will lead to water entry. It’s not a roofing problem specifically, but as contractors who care a lot about the overall condition of a building, particularly near or around the roof system, we often make it a point to also work with things like deteriorated chimneys where they meet or close to where they meet the roof system.
We looked at a handful of pictures this past week and today we’re going to look at several more of the deteriorating brickwork. Another close view follows in the next picture below.
You can see they’re also different types of damage happening here at this chimney. The brick is spalling, and it also looks like much of the damage that’s happened to the chimney really could have been prevented or at least stopped in it’s tracks at some point or forestalled if a good contractor like ourselves got up and looked at this roof a few years back. We may have been able to notice and point out that the chimney could use some upkeep and care. Typical routine maintenance like this can extend the life of a chimney significantly.
The chimney joins to the roof, in most cases, at a counter flashing. Generally the horizontal or low slope roof membrane will meet against the base of the chimney and then turn upwards. That upward turn is base flashing and often there will be a counter flashing then which sits on top of that base flashing and will often be embedded slightly into the edge of the base of the chimney.
Both base flashing counter flashing are two separate but complementary types of flashing that work together to seal, or overlay, the transition between a chimney and a low slope or flat roof. (Often the overlap between the base flashing and the counter flashing,.will in fact, create a roof that avoids leakage, but is it it isn’t always an actual seal. In some cases that joint, when submerged in water, will still leak, even when installed properly.) It’s important to understand this difference, because in some conditions of ice damming, areas of counter flashing can still actually leak.)
Another contractor, unrelated to ourselves, in the past, has come and smeared asphaltic mastic on top of the flaunching area of the chimney. This type of application might work in an emergency leak type scenario where something needs to be done very quickly without time to make a long-term repair. It’s not of the quality or the type of repair that can can be considered long-term in nature. Asphaltic mastic like this will generally deteriorate very quickly when exposed, in full sun, to unmitigated ultraviolet rays.
A previous roofing contractor, who took a more holistic view of things, could have pointed out to the client or the owner of the building, years ago probably, that these bricks could use at least repointing and or selective replacement to extend the life of this chimney. Now, in this condition, the work is likely to be more extensive. More reduced scopes of repointing and or refurbishment are not as applicable or sufficient at this point now.
As you look at the bricks, you can see that they’ve deteriorated and spalled for several reasons. They may have been repointed with an overly hard mortar in the past, that type of mistake happens very often with contractors who don’t understand the differences between historic and modern brickwork. Here, in Washington DC, we particularly recommend that clients use contractors like ourselves who specialize in historic properties. The difference can be really important.
This particular chimney has a relatively new stainless steel cap installed. We recommend caps like this with a spark arrestor, even if the chimney is not being used for an internal fireplace. Originally, at the time of the initial invention and usage, Spark arresters were used, particularly, to keep wood burning fireplace embers from drifting up out of the chimney and burning down the house or neighboring properties. Nowadays though many chimneys are used for mechanical devices that do not actually admit burning embers. The term spark arrestor still applies though and the product or material is still useful because today, more than anything else, it helps to keeps rodents out of the chimney.
We provide this information here on our blog to help our customers and future clients and we recommend every building owner in DC who values the longevity of their roof (and their investments) and building use a contractor who values the simple and important principles of proper roof construction like Dupont Roofing DC. Learn more about our company and the proper techniques of working with roofing on historic buildings in Washington DC here on our blog at DupontRoofingDC.com, and you can call us at (202) 840-8698 and email us at dupontroofingdc@gmail.com. We are happy to help and at least talk through options.
