Metal Roof Recoating – Part II

This past week we took a look at a low slope roof in Capitol hill, Washington DC.  Low slope roofs are often referred to as flat roofs.  This particular roof is covered and clad with a standing seam metal membrane. This installation is historic it has probably been on the building for over 50 years. The metal wasn’t in great shape, but the client in this particular circumstance needed a minimal type repair. We would definitely recommend a full replacement, but under the conditions we did what was needed for the situation.

Read – Metal Roof Recoating – Part I

When you look at the overall roof, you can see that there is a significant amount of dirt and dust that has built up on the rooftop over the years. There’s several different ways to clean the dust and debris from the rooftop. Trisodium phosphate is one of the best materials for cleaning and bonding to several types of materials, but it’s not compatible with all materials and if a rain guttering and rain leaders system is not properly operable and connected water from the roof could be diverted to adjacent hardscape or landscape areas  which could potentially lead to damage to delicate ornamental plants. A few weeks back we addressed the potential issue in another weblog: “phosphate alternatives [are recommended].  The use of phosphates, and recapture of phosphates is a potentially significant issue for both the environment today and the long term sustainability of survival on the planet Earth, so we caution against the use of phosphates without extreme care as we recommend that if it is used, care be applied to use it sparingly and judiciously.   Phosphates are simply a scarce and non-renewable resource here on Earth.”  

 The picture below shows the specific areas of repair.

areas of repair metal roof recoating

Preparation is always part of the process before starting any type of chemical application on a rooftop. And this particular case, a tree had recently been cut down by a neighbor and the neighbor’s tree cutting contractor had left an enormous amount of branches and tree materials scattered over our client’s roof. We remove these elements before starting the work. Repeatedly and sadly, we find damage done to our client’s roofs and discarded materials left behind by other contractors.  

damage to metal roof falling leaves

Once the substrate area is prepared, a fabric / textile reinforcement is embedded in a low viscosity primary application.   Two-component systems often use polysiloxane chains in long molecules, in chemical form, and often supported and reinforced in solution with silica type resins and speciality compounds which add both fluidity and fortification for embedment.

Polymers can be used in single or two-part applications.  Single component coatings applications rely on air exposure to cure.  By comparison, two-part applications use a catalyst to chemically activate (and promote / hasten the reaction almost irrespective of environmental and weather conditions at the time of application) the curing and setting process.  

textile reinforcement

Smart proactive replacement, construction, upkeep and maintenance of low slope roof systems requires an enthusiastic interest and understanding of 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, fill out the webform below and drop us a line.  We will be in touch if we can help.

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