Front Porch Roofs: Key Maintenance Tips and Common Repair Needs
This past week, we took a specific look at one of these roofs at the front porches in this group of row homes, as you can see in the photos below. We happened to do a significant amount of repair work at that particular roof but these other adjoining roofs are built joined together, similar to how the main roofs on top of the buildings also joined together.
Here at the porches though, they are abutted to each other without a parapet or a demising wall. One roof edge touches the next, and one roof overlaps the next as they go down the block. Like most streets this street has a bit of a grade or slope, from one building to the next, in descending order.
In last week’s blog article, we looked at issues related to delamination of the membrane and ponding at spots that corresponded with areas of seams in the roll roofing. Areas of ponding water that are coincident with seams are particularly problematic because seams have a tendency to delaminate over time with exposure to elements, both in freeze-thaw cycles and with deterioration that happens naturally from exposure to ultraviolet rays. As well, where ponding water builds up, that overhydration also has a tendency to deteriorate the seams through dissolution.
It’s not that ponding water is okay in the field of a membrane roll, but it has a tendency to deteriorate on a slower time scale and a lower tendency to cause leakage if the ponding is at least not coincident with seams, at least. Both circumstances are still problematic, though, nonetheless.
Today, we’re looking at neighboring roofs with different types of problems. The roof shown in the picture below is possibly made from a modified bitumen system, but normally modified bitumen membrane is a bit thicker than felt paper or built-up type roofing materials. Built-up roofing generally has multiple plies, each overlaid on top of the next and embedded with a liquid hot mop applied asphaltic pitch.
It looks like this membrane also had an aluminum type paint applied on top of the roll material, but all of the substrate layers and surface applied coating on top are in a rough and deteriorated condition. We think this roof is slowly leaking at several locations.
Not only are there typical areas of ponding, but here it’s worse because there are recessed canals which allow water to not only pond but probably infiltrate below into the substrate decking. Also, without a parapet at this location, the leakage from one roof can easily infiltrate into the roof across the property line at the neighboring porch.
Here in the next picture below, you can see a different but obvious big problem, the roll membrane which is applied in layers that overlap at joints, is delaminated and separated from its substrate. That overlap creates a seal which is essential for the membrane to work properly.
At another adjoining roof on the opposite side, there’s another large ponding area around the drain where the substrate deck boards have become suppressed. As you might imagine, intuitively, for a drain in a low slope roof to work properly, the drain orifice has to be the lowest part of the remainder of the low slope roof. That means that every other part of the roof has to be higher and really the outer edges of the roof should be the highest points.
Every point from within that perimeter then must continue in a line or direct path to the drain which is consistently lower from the outer edge towards the drain. Here, in this example, the roof may have proper slope at all points, but at an area roughly 3 ft around the drain orifice, the roof surface is lower than the drain orifice. That creates an area where water builds up and then only dissipates through leakage through the coincident seams or through slow evaporation over time. In most cases, particularly when there’s cold weather, that time period of evaporation far exceeds the acceptable limits.
When you look closely at this area, you can see that not only is it a location where dust and debris build up at each successive rainfall, but also at that area, biocolonization or growth of moss and or other organisms have started to take root. Whenever you see signs like this, it’s an indication that the roof has excessive ponding and probably will lead to significantly accelerated deterioration of the roof system.
As you go down farther down the block, looking at the other neighboring buildings, the porch roofs seem to get increasingly worse. Clearly, a contractor is needed, in the neighborhood, to take care and repair these roof systems. Whenever upkeep, maintenance, incremental repairs, Etc are completed, it leads to lower overall cost expenditure because it’s a lot less expensive to maintain these systems than it is to have to complete critical more extensive repairs or replacement.
We mentioned moss and / or small microbial type growth at some areas where water was ponding, but at this particular example, you can see, there’s a complex plant life growing right out of the built up debris at the ponding area. Even though the plants are not very big, they’re definitely big enough to be a problem or indicate a problem for the roof system. And as well there’s a significant variety of different plants there.
Just in this one area we can see a small red maple, clover, ground ivy, and even possibly a dandelion plant growing. Simple routine check-ups for roof systems are really important, cost effective and well worth the effort.
Another picture even closer follows below.
We provide this information here on our blog, and our website, 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.
Our company specializes in flat roofing here in Washington DC and we’re happy to help building owners of almost all types. 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.
