engineering

Roof coating

Roof coating is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Roof coating rather than just read about it. In short: A roof coating is a monolithic, fully adhered, fluid applied roofing membrane. Many roof coatings are elastomeric, that is, they have elastic properties that allow them to stretch and return to their original shape without damage.

Key takeaways

Roof coating belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Roof coating to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Roof coating from memory before moving on to harder problems.

Reference excerpt

A roof coating is a monolithic, fully adhered, fluid applied roofing membrane. Many roof coatings are elastomeric, that is, they have elastic properties that allow them to stretch and return to their original shape without damage. Typical roof coating dry film thickness vary from paint film thickness (plus or minus 0.075 mm (3 dry mils) to more than 1 mm (40 dry mils). This means a roof coating actually becomes the top layer of a composite roof membrane and underlying system. As such, the roof coating is the topmost layer of protection for the membrane, receiving the impact of sunlight (both infrared and ultraviolet (UV)), rain, hail and physical damage. Roof Coatings should not be confused with deck coatings. Deck coatings are traffic bearing - designed for waterproofing areas where pedestrian (and in some cases vehicular) traffic is expected. Roof coatings will only waterproof the substrates but will not withstand any kind of on going use by people or vehicles (such as walkways, patios, sundecks, restaurants, etc.).

Benefits

Roof coatings are seamless and when installed correctly, can solve roof leaks on almost any type of roofing material. There are exceptions: "professionals do not recommend using cool coatings over existing shingles. This technique can cause moisture problems and water damage because the coating can inhibit normal shingle drying after rain or dew accumulation, allowing water to condense and collect under the shingles." Field-applied reflective roof coatings can extend the useful life of nearly every roof substrate keeping a roof surface cool and providing a level of protection from the sun and weather. However, coating asphalt shingles and built-up composition roofs requires more caution. The National Roofing Contractors Association’s (NRCA) director of technical services has stated "The roofing industry is aware of a number of issues that could have negative consequences for field application of coatings over asphalt shingle roof systems. Anyone considering this type of application should be aware of the concerns so they can weigh them against the benefits claimed in coating product promotional materials." Roof coatings can add 25 years to the service life of a roof and reduce the amount of discarded roofing materials that end up in landfills. The infrared image on the right shows 79 °C (174 °F) on the uncoated (black) section of the modified bitumen roof. The coated (white) section is 26 °C (79 °F). Field studies have shown that cool roof coatings can lower rooftop temperatures and reduce air conditioning bills.

Limitations/Risks Most flat roofs are not perfectly sloped, causing water to puddle in some areas, in particular around the drains and scuppers. Many roof coatings are not rated or warranted for "ponding water", and thus might fail pre-maturely if exposed to standing water over long periods of time. Serious consideration should be given to the performance and limitations of the coating being selected. Some manufacturers will warranty their coatings including ponding water. Typically, manufacturers for acrylic roof coatings do not include warranties for ponding water, while some polyurethane and silicone roof coatings manufacturers will.

Types of Roof Coatings There are many different types of roof coatings with various purposes, formulated with various chemistries. The primary purposes of roof coatings are: resaturation of old roofs to extend the service life of the roof, reflectivity to create a "cool roof", and toughness to provide a wearing surface on the roof that can resist abrasion from foot traffic or other physical damage, such as from hail. Primary materials used in roof coating formulation include acrylics, asphalt, butyl, coal tar pitch, polyurea, polyurethanes, polyvinylidene fluoride, silicones, and styrene-butadiene.

Application

Roof coatings are easy to install. Smaller roofs in good, serviceable condition can be a weekend do-it-yourself (DIY) project. Larger roofs with leaks and ponding water issues should be coated by a qualified professional. Additional roof coating products, such as foam or coatings designed for seams, may be required underneath the main coating layers. Supplement coating products are used to reinforce damaged or leak-prone problem areas.

Tools and equipment High pressure airless spray equipment, pressure washers with a rotary (turbo) nozzle, roof repair equipment and basic painting tools such as brushes, rollers, putty knives, and scaffolding.

References

Illustrations

Worked examples

Example 1 — a first encounter with Roof coating

Start with the simplest possible case. Write down what Roof coating claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Roof coating before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Roof coating ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Roof coating

In research: Roof coating appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Roof coating in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Roof coating is common in secondary-school and first-year university syllabi. It links to neighbouring topics Building materials, Roofs, so understanding it makes those chapters shorter.
In everyday life: Look for Roof coating outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Roof coating in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Roof coating means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Roof coating out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Roof coating in simple terms?

Why does Roof coating matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Roof coating?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Roof coating.