Various choices are available for all roof types. Usually the type of material used is based upon factors such as cost, climate, and type of roof design.  Roofers often make recommendations based upon service experience and supplier support.  Some are more sustainable than others.

Metal panels are used for both low and steep sloped roofs. They are the roof of choice for aesthetics and sustainability. They are most easily maintained and generally require the least maintenance. They also come with an initial higher price tag. They are referred to as either structural (the roof supports itself) or non-structural (requires deck support).

Low sloped roofs are usually structural roofs; the panels are designed to overlap and be connected together and provide a rigid surface that support loads and also sweep water away. They usually are built atop perlins (evenly spaced open supports) beneath and should be of a heavy enough gauge that foot traffic or dead loads do not damage seams or panels. Do diligence when pricing a new structural metal roof to compare steel gauges. Unscrupulous roofers lure purchasers using lowball replacement pricing based upon thin metal or siding for roofing. The flaw of this thinking comes back to haunt buyers too soon to make this a practical decision. These can become chronic problems once seams open up, because even the weight of workers attempting maintenance can open more seams and cause more grief.

Steep slope roofs can be non-structural, meaning that a full deck is below and the panels do not support loads. Non-structural roofs also are referred to as Architectural roofs, largely because they are designed primarily for aesthetics. The skin essentially sheds the moisture but it is the slope and decking below which largely influences waterproofing. They are held together by a series of hidden metal clips fasteners.

Lap types vary, including side seams, exposed fasteners, elevated standing seams, hidden metal clip fasteners or a hybrid. Exposed fasteners require periodic tightening. After a period of time, fasteners can come loose from the years of thermal induced movement. After components are inspected, and damaged or missing ones replaced, these roofs are easily maintained with an approach that provides thorough attention to fasteners, seams, and a protective finish coat to extend weathering. This is where choosing a coating correctly, is meaningful.

Built-up (multi-ply) and Modified Bitumen are some of the most common membranes for flat roofs (“flat” should not be less than ¼”/ft. slope per NRCA guidelines). Though initial costs are higher than other options, traditional installation techniques, durability, and longer term maintainability lend to their popularity and economy. These involve multiple plies which provide greater environmental protection. They may be granular covered to enhance protection against UV and hail. Most all are insulated, so care should be taken to remove any damp insulation and rebuild the affected area when doing any maintenance. They accept maintenance coatings well. These 99% of the time are “hot applied” – temperature of the bitumen is important during installation to get proper bonding. The disadvantage is the danger of burns (hot kettles with mop-on installation) and fire from torch-on modified bitumen. VOC laws and insurance issues are making their installation more difficult in some areas. If attended to properly they are renewable without full tear-off.

SEBS Modified Cap Sheets to their credit contain SEBS rubber, which is the most sable thermoplastic known. They are some of the most expensive of Modified caps sheets and they are among the more durable. SEBS is excellent in all climates, hot and cold. Often however the rubber is blended; more typical is (80%) SBS (see below) with just 7% SEBS and this rubber blend typically makes up <7% of the membrane. The balance (93%+) consists of bitumen and fillers. They are usually applied into hot asphalt subject to the above considerations (see Built-up and Modified Bitumen). These cap sheets always have either a granular surface or are flood coated. They require application of a highly reflective maintenance coating to achieve energy savings. If attended to properly they are renewable without full tear-off.

SBS Modified Cap Sheets contains SBS rubber which is a thermoplastic with good weatherability. They are excellent in all climates hot and cold. However, unlike SEBS rubber, SBS rubber undergoes crosslinking, which makes it brittle as it ages. They are usually applied into hot asphalt subject to the above considerations (see Built-up and Modified Bitumen). These cap sheets always have either a granular surface or are flood coated. They require application of a highly reflective maintenance coating to achieve energy savings. If attended to properly they are renewable without full tear-off.

APP Modified Cap Sheets (Atactic PolyPropylene) is not actually a rubber but is more of a plastic polymer and is less costly. It installs easily and is easily maintenance coated.

Timely roof maintenance performed on a regular basis saves money. Full protective coating done periodically can save 2/3rd the cost of replacement and prevent costly business interruption. It interrupts the replacement cycle.

Your tax bracket adjusts your savings upward. Roof maintenance is 100% deductible the year it is performed (consult your tax preparer for details). Roof replacement is not. If your federal rate is 39% and state is 6%, knock 45% off the maintenance costs to get your effective cost.

Most roofs can use maintenance. The only ones that don’t are either new or so far gone that it’s too late.  The challenge every building owner has, is knowing when it’s too late - or, too early. Avoiding “too late” is always the mantra of the owner. The minor extra cost of “too early” is typically marginal in this equation. Always include gutters and drains in your inspections.

Roofing experts, professional property managers, and associations concur on when it is to be performed.  At spring and fall the entire roof should be evaluated and planned maintenance performed. After any serious storm or the first evidence of problems is the next time to do it. Spring inspections assess and address winter’s roof damage. Fall’s attention to the details prepares it for the rigors of winter, which often times presents greater challenges with exposure to ice, moisture, freeze/thaw cycles, etc.

Specialized roof cements and coatings are most common for roof care. If they are developed and applied properly, they present the most cost effective approach to extending roof life. Common threads of effective products include weather resistance, UV stability, and as recognized even more so now than ever – color.

Greater attention has been given of late to white colored roof coverings for their energy savings benefit. What once was purchased for the ability to reduce summertime cooling needs, has received more recognition for its ability to control maintenance needs. There is a good deal of evidence for this. Bright white roofs (especially) resist heating. This puts less stress on the system below. But more importantly, it greatly reduces the thermal induced movement resulting from cool rains on a hot surface, expansion and contraction, therefore aiding in reducing future maintenance needs.

Theories abound as to the best timing to perform full coating maintenance. Application should be avoided during very cold temperatures, since the expansion of the roof covering when heated up may expose other deficiencies that would best have been addressed during the reinforcement stage prior to coating.  Also, underlying dampness is not easily dissipated on cold roofs, resulting in entrapped moisture which should be avoided at all costs. Waterless coatings are better suited for applications when night time temperatures can teeter to freezing or below. Waterborne latexes are damaged by freezing before cured.

Dark colored roofs can warm up sufficiently even on days of frost. The applicator’s time frame for doing work each day goes down in autumn so his costs may go up. Many are willing to absorb this as they know their days are limited for work that year. Regardless, this can be the best time for you and them depending upon their workload and your preparedness for going into winter. Remember, a roof requiring maintenance going into foul weather will only be more vulnerable to greater damages both to building and content, resulting in greater expense if delayed. In retrospect, this may be your best and most economical time to do it.

For emergency temporary repairs with cements, all gloves are off. A dry surface is generally required. Some cements claim they’ll stick to a wet (but frost-free) surface. While this may be true, it disregards damages and ongoing decay resulting from trapped moisture. These areas always have moisture. Remember, they were leaking. Freezing and thawing compounds the situation. You’ll do well to have it re-addressed in spring time when something more extensive and appropriate can be done. IR infrared photo scans will detect underlying moisture and are recommended on all flat roofs to get the greatest long term value of coating maintenance.

The downside of “too early” is that you may have put out a little money ahead of time. That’s all. But the downside of the other, waiting until it’s too late, is disastrous.

Most roofs benefit from a protective coating provided that they are applied before so much damage has been done that the roof life can not economically be extended. It is not unusual for isolated areas to be replaced, which is more economical when full roof replacement isn’t necessary. Some areas of roof weather harder than others.

Roof coatings come in three forms based upon how they cure; mixed with water (waterborne), mixed with a different solvent (solvent based), or a catalyst (parts mixed together react and result in curing). The 1st two cure by evaporation. Catalyst coatings are less popular due to material and application costs.

Asphalt coatings typically have the least initial cost and are applied for a variety of reasons. They are more temporary and can be applied in areas without doing an entire roof since they do not require a continuous film.  They are more vulnerable to UV and weather and require more frequent application. Asphalts are blended for either higher or lower melt temperatures. One resists hot temperatures without flowing. The other resists cold temperatures without becoming brittle. They are either black or pigmented with aluminum and produce minimal to no temperature reduction.

Elastomeric coatings (coatings that stretch) have become most popular because of their greater durability and energy savings since they can be made in a full range of colors including bright white. These are longer lasting provided that they are formulated properly. Having “100% acrylic” or “rubberlike qualities” does not tell whether the ingredients are the most suitable for your application or even of great volume in the product. Physical properties will, however, compare for you what you are getting and can give you a reasonable prediction of relative performance. Elongation and tensile strength are the primary features elastomerics are purchased for. They are available in white and a variety of colors, making them popular for aesthetics and temperature reduction. Elastomerics will perform over a wider variety of temperature conditions. The quality of UV resistance is essential.

Water based elastomeric coatings are best used over breathing porous surfaces such as stucco, block, concrete walls, and certain polyurethane foam roofs. They have an open particle structure that allows vapor to dissipate. They are characterized by a high “perm” number. For this reason there are better answers for substrates such as metal that is subject to corrosion, roofs that tend to pond water after precipitation (invades the voids within the coating structure resulting in failure), and some felt roofs. Water based coatings are vulnerable to wash off from rain or heavy dew, and freeze damage before curing. Consequently their use should be guarded in spring or late fall when freezes occur. The water based coatings “chalk off” faster then their non-water containing alternatives do but provide for easier applicator clean up.  Water contained in water based products can trigger flash rust, and the larger particle sizes that allow moisture migration also hinder effective rust prevention

Non-water based (petroleum based solvent or catalyst cure type) elastomeric coatings are best used over surfaces that do not need to breathe moisture (metal, dry substrates, rubber modified bitumen, etc.). There are only a few manufacturers capable of producing these due to the technology and investment required. These coatings have an extremely low perm rating that act as a vapor barrier and result in a superior seal. Consequently they are tight and often offer superior physical properties. They are preferred for extending application seasons. Using these type products is not recommended when a damp substrate exists (caution to not apply any coating over any damp substrate per NRCA and most manufacturer requirements). This can result in problems of concealed damages, coating blisters or delimitation between the substrate and coating.

Some manufactures supply a variety of coating types. A simple rule of thumb applies here to evaluating them. Ask for certified independent laboratory results that compare their product to established standards and even competitive type products of others. Then compare the physical properties. These are what stay with the property long after the work is performed. Independent reports provide you greater assurances of the properties and seriousness of the supplier. Product capability is not an area to be pennywise and pound-foolish.

Fact. A highly reflective roof covering can reduce summer time rooftop temperatures 100° F. or more (source: EPA). This translates to immediate savings inside. But beware of wolves wearing a sheepskin coat. Your first and primary reason for buying roof coating for economics should be roof maintenance. That offers more certainty. So, choose a roof coating carefully, looking at all features and benefits. Under roof savings can be influenced so much by activities within the building (heat generating), area of windows relative to roofing, window and even building/roof orientation – that predicting savings is less accurate than predicting benefits of extending roof life. West or southerly exposure makes buildings warmer. All else equal, choose the coating with the energy saving pedigree. It delivers more bang for your buck, and also aids in controlling future roof maintenance needs.

The EPA recognizes roofing that is capable of producing the best energy savings returns by awarding the product with the Energy Star® designation (http://www.epa.gov/hiri/strategies/coolroofs.html). Energy Star® roofing is established as capable of providing typically 10-15% utility savings during the hottest months by reducing peak energy usage.  They estimate it can save up to 50% based upon reducing air-conditioning requirements in certain conditions where a/c need is marginal. This is determined totally by reflectivity. So beware of mystery ingredients promising special powers. Usually the supplier somewhere divulges that these powers only apply to “white”.

Unfortunately companies have misrepresented products as complying with Energy Star® – and the program, while dutiful in requiring tests results to be submitted, has no ability to verify results of submitted products submitted. Also, companies knowingly or not may modify their products, and not update their Energy Star® compliance although they maintain use of the logo.

As a consequence, formidable bodies such as the California state government have required (by law) that all products have CRRC™ Cool Roof Rating Council approval before any coating or roofing is used (anywhere in the state). CRRC does require that independent lab tests be submitted using only approved labs. But buyers beware. Be certain that the CRRC reference you receive from your supplier is the product’s approval and not just a supplier’s “membership” with CRRC. Membership costs little and does NOT represent product approval. Those with a “membership” can display the CRRC logo but it must be the one showing “Member” below it. They can be listed as members on the site, but product approval is a separate matter. Product approval by CRRC is guarded closely by CRRC and conforming suppliers agree to random product testing.