Why Chimneys Falling Apart and How to Fix Them
In several cases before, we’ve looked at the way that chimneys can affect flat roof systems. Most roofing contractors don’t deal with chimney problems at all, and even though it’s not our company’s particular focus, we are cross-trained in both areas of masonry restoration and flat roof repair and of course installation of new low slope or flat roofs. That’s what we really focus on as a company, flat roof installation and repair here in Washington DC. However, often, we find that chimney problems affect the roof and can actually cause leaks to emanate from the area around the roof.
So often, we take responsibility to look at and or diagnose and address some of the issues related to chimneys and associated deterioration. In general, chimneys require a different life cycle management process. They deteriorate in different ways over slightly different timelines. There are several components to almost every chimney even though there are many similarities that occur from building to building and from chimney to chimney.
There are several different types of rooftop membranes, found here in Washington DC. The one of the picture below and above is a modified bitumen roof at the left hand side and a standing metal seam roof on the right hand side. These roof systems are basically co-joined at the sides. Just like the typical layout of an average row home here in Washington DC, there’s often neighboring buildings that abut each other or are built together but as separate units or houses here, it’s built in the same way.
The roof, essentially, in this case is separated by a parapet wall that extends just above the majority of the flat or near horizontal low slope roof system. That particular parapet wall is covered with a metal coping. We often recommend that a sheet metal coping is installed at the parapet between buildings. This can help significantly, because different types of roof systems usually have different elements which terminate, and need coverage. In most cases, a single metal coping can span the edges of both roof systems at neighboring properties.
If you look closely at the pictures above and below, you can see the chimney falling apart. As moisture enters in through this deteriorating masonry, it will hydrate the brickwork and mortar in the chimney itself. As the water goes downward, it will eventually filter through other parts of the same masonry assembly and will eventually leak outward into the plaster or drywall that surrounds the chimney, on the interior of the building. In cases of more modern types of finishes in the home, where there is wood framing and drywall, this type of festering leakage can cause significant issues of biological growth.
You may notice that there’s chunks of mortar and masonry strewn across the area of the metal roof. It looks like the chimney is basically crumbling and the chunks and pieces of that masonry are falling down onto the rooftop system. This is important because in a really clear and direct type of concern, the chimney masonry will start the leak as the bricks and mortar are falling apart. As water comes through that masonry assembly, it will go down into the house through the chimney but can permeate to other parts of the building.
In cases like this, the chimney itself goes through the attic space and through the framed ceiling assembly. It also will generally run through a chase that goes up through the adjacent rooms in the house. As that water starts to permeate in leak through into the chimney, it will dissipate and or amass at different parts of the masonry assembly. From there, it can leak outward and or even wick or permeate outward into the adjacent plaster of the ceiling or the chase of the wall which contains the fireplace.
In cases where homes or rooms of a home have been flipped or modernized and there is wood framing with modern drywall, those elements can be equally problematic because they create a breeding ground for mold. Wood can rot, and particularly the gypsum face of drywall can be a substrate that promotes mold growth when over-hydrated. Conditions vary significantly from one example to the next, but we’ve seen cases where wet drywall needs to be removed and removed carefully because it may have organic growth that may or may not be harmful, depending on the exact type of microorganisms.
The picture below shows the side of the chimney where the chunks of the spalling bricks have fallen away from the chimney went to the rooftop. They likely didn’t cause any significant damage when falling from the chimney, but this chimney happens to be relatively low and in close proximity to the rooftop planar surface. In other cases, where chimneys are taller than the adjacent rooftop membrane it might actually cause damage if large chunks of masonry fall down at once.
Here though, the bigger concern may be that other contractors may not be careful. Sometimes other contractors will walk around on top of these masonry debris and the pressure of their large feet stepping on these bricks and chunks of mortar might actually cause holes or damage to the rooftop membrane. Our company is generally pretty careful about things like this but it’s a good idea to stop the deterioration at the source.
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.
