Flat Roof Leakage Caused By Solar Panels

Read To Understand Why Flat Roof Leakage Can Be Caused By Solar Panels

In a series of two articles, one this week and one last week, on our website, we took a look at a type of photovoltaic solar panel which does not necessarily require damage to the roof for mounting and attachment.    We contrasted that type of flexible photovoltaic system with the traditional hard panels which are mounted or secured to the rooftop or rooftop parapet, if they are not secured with a heavy ballast. Today, we take a closer look at solar panels bolted to a rooftop and the problems associated with bolting through a near horizontal parapet. The outline of article series, of two articles in total,follows:

This week’s Part I on the topic of Flat roof leakage caused by solar panels:

  1. Building Code and AHJ requirements
  2. Common PV solar industry practices in DC 
  3. Inherent problems with DC Solar installation 

Next week’s Part II on the topic of Flat roof leakage caused by solar panels:

  1. Possible reasons why the bolting problem is so prolific
  2. Multiple points of potential water entry
  3. Thermal movement in metals of different thicknesses

Back in late 2022 we wrote an article on our website about The problems inherent in installing solar panels bolted directly through a flat or low slope roof parapet. It is so common that we encounter problems associated with this type of installation all over Washington DC.   The referenced article can be seen at the following link:

 Why bolting solar panels through parapets is bad

why bolting solar panels through parapets is bad

Today, in this article, we present new information, from the field, of more improper installations and pictures of the details.

Building Code and AHJ requirements

In last week’s article about the damage created in roof membrane from improper solar panel installations, we discussed some of the shortcomings related to lack of oversight by DCRA and other AHJ is related to the regulation of construction in Washington DC:  

In Washington, DC, the building code places the responsibility on solar panel installers to ensure their panels adhere to the installation instructions provided by both the aluminum coping and roofing manufacturers. This approach might appear counterintuitive in light of the International Building Code (IBC), which, despite its name, isn’t universally mandated. While the IBC carries the label of an “Authority Having Jurisdiction,” it lacks actual authority. Instead, local jurisdictions, both within the USA and internationally, can choose to adopt the IBC rules in full or in part, according to their preferences.

Most roofing and coping manufacturers stipulate that fasteners shouldn’t be used in nearly horizontal portions of the coping metal. Although the DC building code permits penetrations through such coping areas, it requires strict conditions for approval, which solar panel installers in Washington, DC frequently neglect to adhere to. Consequently, we often encounter instances of water leakage into parapets through coping, stemming from water entry at the mounting points of conventional PV solar panels.

solar panels mounted on flat roof
The picture shows a solar panel mounted on a rooftop parapet.  The parapet coping is a reddish color aluminum metal custom bent to fit over the existing parapet wall.  The solar panels are set on an aluminum umbrella frame, in the case, held about 14″ away and above from the TPO rooftop below.

Common PV solar industry practices in DC 

Despite the indirect, yet prevailing proscription in the building code that forbids the installation of fasteners, bolts, anchors or mounting hardware for solar panels through copings at horizontal or near-horizontal atop flat roof parapets, the constant recurrence of this disconcerting practice in Washington, DC is constantly and conspicuous. One of the biggest factors, essentially creating a moral hazard in the industry is the absence of regulatory oversight in this niche of the industry. It is notable that the District of Columbia’s Department of Consumer and Regulatory Affairs (DCRA) serves as the ostensible custodian of the impositions of the building code.  Effectively, DCRA is one of the few, of all the various authorities having jurisdiction, which is actually charged with the enforcement of the adopted building code in Washington, DC. However, a notable aspect here is that the DCRA does not take the responsibility of inspecting rooftop solar panel installations to ensure they comply with the required standards.  They will not inspect construction or installation work on rooftops and this is one of the major reasons why we have the majority of contractors in Washington, DC installing membranes and equipment improperly in this city.

This lack of regulatory oversight leads to a situation where the authorization for solar panel installation is primarily given during the architectural or engineering design phase. This approach bypasses field-level enforcement and often results in a lack of precision in addressing crucial details, such as the proper installation fasteners and bolts for mounting, as well as the sealing methods needed to prevent leaks. This oversight tends to disregard the essential need to protect the existing waterproof membrane, which plays a critical role in guarding against the weather conditions of our region.

Consequently, the recurrence of this problematic practice can be attributed, at least in part, to a regulatory framework that, despite ostensibly requiring (not outlining, and that distinction is important necause the code effectuates its requirements indirectly through reference which is a secondary yet important causal factor to why we have such a disconnect in oversight and enforcement of the building code in DC) the operational guidelines for solar panel installation, lacks effective enforcement in actual practice. This discrepancy between regulatory directives and real-world implementation creates an inconsistency between established standards and their practical application.

solar panels connecting bolts flat roof leakage
The picture shows an aluminum solar panel pulling or mounting beam spanning between parapets.  The perpendicular mounting bar is secured to the parapet with smaller aluminum clips, small pieces of metal cut aluminum angle bar, perforated with slotted openings to allow the installation of connecting bolts.

Inherent problems with DC Solar installation

The National Roofing Cobtravtorsassocistion has published diagrams showing proper approved methods of solar panel array systems.   According to the NRCA, and some roofing suppliers, a low-risk installation of a solar array system is achieved by mounting the panel system on a raised rack and the rack legs flashed to maintain continuity with the substrate roof membrane.  The caulking installed by the PV Solar installer is not flashing.  Installations with continuous flashing provide mounting stand UNDER the roof membrane, not through the roof membrane.  

There are two main inherent problems with the types of installations, by solar panel installers shown here:

1. Multiple points of potential water entry

This type of fastening without flashing around the fastener creates multiple points of potential wate entry, multiple points and pathways which water can travel to enter the building.

2. Thermal movement in metals of different thicknesses

Without proper flashing, without a continuous connection to the substrate membrane the applied sealants are tengas, they breakdown in an accelerated timeline from exposure to ultraviolet rays in sunlight 

solar panel frame coating to prevent leakage
The solar panel frame, secured by a pulling bolted to the rooftop coping, is shown in the picture above.  The bolts and the brackets or clips in this picture have been coated with a special coating, by our company, NOT the solar panel installer, to prevent water entry.  This type of preventative application may provide the only defense from waterventry but it is a reactionary type of application.  This type of surface applied application is still susceptible to failure related to differential expansion of the substrate metals, and accelerated deterioration from exposure to ultraviolet rays.

In an upcoming article around the same topic, we will talk about the reasons why The issue with aren’t improper penetrations or mounting fasteners or mounting locations is so prolific and Washington DC.   We will also discuss the reasons why each faster penetration appears to be one potential source of Witter ingress, but diagnosing and repairing Or ceiling the area potential water entry is a bit complicated because each faster location may actually create or have multiple.  As well, we will also discuss some of the reasons there is a significantly higher than normal amount of material movement at coil stock and coping metal locations, especially where they meet heavier metal angles or i beams as used in solar panel mounting racks.

Smart proactive replacement, construction, upkeep and maintenance of low slope roof and mansard roof systems requires an enthusiastic interest and understanding of historical methodologies, waterproofing principles, and building science.   Here in Washington DC, historic and modern residential and commercial buildings are extremely expensive and the roof and related systems provide the shield that preserves the building. 

We encourage all of our clients, and all readers of this article and to our blog in general, to prioritize the value of quality construction and building maintenance, and develop a relationship with our company.  You can learn a lot more on our blog.  Feel free to check it out.  If you have questions about the roof and related systems of your building in Washington DC, contact us or fill out the webform below and drop us a line, it’s quick and easy.  We will be in touch if we can help.

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