Helpful tips and advice for home maintenance from your roof to your porch.
What kind of roofs can be coated?
Almost all types of roofs can be coated. Some examples include metal, spray polyurethane, single-ply, modified bitumen, Built-up roof (BUR) systems, etc. Without special treatments, ballasted and gravel surfaced membranes are not typically acceptable roof surfaces for coating membranes.
What types of reflective coatings are available in the market?
There are several types of reflective roof coatings that impart varied reflectance rates/ values. Typically, the reflective coatings are what are commonly referred to as white coatings and there are also aluminum coatings typically used with asphalt. Highly reflective white roof coatings are typically comprised of acrylics, urethanes, silicones, SBS, SEBS, and other types.
How is the coating applied?
The coating can be applied using spray, roller or brush.
Do I need a primer?
A primer is no substitute for thorough cleaning. However, sometimes primers are required, depending on substrate and type of coating. Refer to your coating manufacturer for specific requirements.
How much coating should be put on the roof?
This depends on the coating manufacturer and the project specifications. When in doubt, consult the coating manufacturer you are working with.
How do I prepare the roof surface for coating?
The roof must be thoroughly cleaned, and allowed to dry thoroughly. This is a critical step to ensure a successful coating application. Be careful not to damage the lap seams. Care should be taken when pressure washing not to disturb the integrity of the underlying roof membrane particularly where there are adhered seams. Refer to the specific coating manufacturer you are using for their specific requirements for roof preparation.
Should I coat a new roof or nearly new roof?
Yes, a new roof should be coated if the building owner wants to add a highly reflective roof coating to reduce energy costs. The buyer should be aware of any warranties provided for a new roof that may violate that warranty during the period it is in force via the use of a roof coating. This will extend the roof’s service life. A reflective roof coating will reduce the heat load on the roofing assembly.
What are the building code requirements for roof coatings?
This depends on the local, state, and federal code enforcement requirements that have jurisdiction in your area. The International Code Council (ICC) provides detailed information on the status of I-Code adoption throughout the United States.
Will a reflective coating extend the life of my roof?
Yes. The coating becomes the first layer of UV and waterproofing protection for the roof, and helps reduce expansion and contraction (thermal shock) of the roof.
Are there any warranties available?
Yes. Coating manufacturers offer different types of warranties depending on your needs and applications.
How long will the coating last?
Based on long-term histories, typically the roof life of a properly applied roof coating can be extended up to 10 years or more. Performance can vary depending on type and conditions, as well as the coating film thickness.
Can the roof be recoated in the future?
Yes. As the coating wears away, additional coating can be applied. Most coatings systems are renewable and sustainable. Refer to the specific coating manufacturer you are using for their specific requirements on re-coating applications.
Do I need a contractor, or can I do it myself?
The coating can be applied by an experienced roof coatings applicator. A roofing contractor is strongly recommended if there are such issues as existing leaks, wet insulation, damaged deck, or manufacturers’ warranties.
Can a coating stand up in ponding water conditions?
That depends on the coating. All roofs should be designed and built to have positive drainage and not allow ponding water. Some coatings are designed to withstand ponding conditions; however, not all coatings will withstand these conditions. Check with your manufacturer to see if your coating can withstand ponding water conditions.
In what weather conditions can the coating be applied?
For water borne coatings, the ambient air temperature should be 50oF (10oC) and rising, with no rain for the next 24 hours. Solvent borne coatings can be applied in colder weather. As always, check with the coating manufacturer.
How long does the coating take to dry/cure?
That depends on many factors: air temperature, wind, roof surface temperature, relative humidity (water borne coatings) coating color and the type of coating applied. For example, some coatings are moisture cured and thus humidity assists in its curing process.
Can I coat a rusted metal roof?
Rusted metal roofs can be coated after the rust conditions have been addressed. If the roof is “white rust” (zinc or aluminum) it can be coated after cleaning. If the roof is “red rust” the rust must be removed or treated with a corrosion inhibiting primer. All rusted fasteners should be treated or replaced.
Is there a tax advantage or rebate program available?
Some states, municipalities and utilities have programs. Check with your coatings manufacturer for further information. As a membership benefit, RCMA provides maintains a database of current information on rebates and tax credits for installing reflective roofs. RCMA’s customized search tool can be used to find the most up-to-date listings of reflective roofing financial incentives available.
Roof coatings are typically classified as maintenance, and in many cases can be written off as such in the same calendar year in which the coating application is completed; check with your CFO for specific details on roof maintenance tax deductions.
How do I maintain the coating?
It is recommended that the roof, including the coating, be inspected semi-annually and after a major storm or high wind “event”. Additional coating may need to be applied to repair damage to the coating and underlying roofing substrate. Check with the manufacturer and/or warranty program requirements.
What are Solar Reflectance and Thermal Emittance?
Solar Reflectance is a measure of the ability of a material (roof coating) to reflect the sun’s radiation. Thermal Emittance is a measure of the material (roof coating) to release trapped heat back into the atmosphere.
Will the coating stop my leaks?
While coatings may potentially stop minor leaks, the roof should be properly repaired and dried prior to coating application. Coatings may be able to seal pinhole leaks, which are leaks not visible to the naked eye. If the roof is leaking, the roof leak will need to be identified and repaired prior to any recoating; do not expect the coating to find and seal the leaks.
Where do I find a contractor to coat my roof?
Check with the coating manufacturer who may be able to suggest applicators who have used their products and have familiarity with the application. Another option would be to interview contractors and ask specific questions about their proven ability to install roof coatings
There are many reasons for a homeowner to want to change the pitch or slope of a roof:
Flat or Low-Slope
Things You Will Need
Are There Really Flat Roofs?
To begin, I’d like to clear up a commonly misused word to describe a flat roof. You should never really encounter a truly flat roof. All roofs should be sloped to drain. Water weighs more than eight pounds per gallon and you never want to turn your roof into a swimming pool; roofs are generally not framed to support significant ponding water. So, it would be more accurate to consider a sloped roof V.S. a low slope roof. I used flat roof in the title because I felt this was common usage.
How to Measure a Roof SlopeThe standard way to measure a roof’s pitch is by its fall over 12 inches. A roof that falls one inch over 12 inches is called a 1 and 12 and would be considered low slope.
Low Slope Roofs: As Good as the InstallationLow slope roofs have a well-earned reputation for being troublesome. Because they don’t shed water well they’re more likely to have leaks, and leaks on flat roofs can be a real pain to track down; you can find yourself chasing water, which is never fun and can make roof replacement the only sure-fire option for repair. Combined with comparatively more expensive installation cost and shorter useful service life, low slope roofs are generally higher maintenance roofs than sloped roofs. However…
Like all roofing systems, a lot depends on the quality of the installation. Some of the newer single ply membranes are coming with 50-year warranties. It is unclear if they will perform reliably for this long, but they seem to be a superior product to some of the older membrane systems if installed well. Many older membrane systems, like torch down, often have about 10 years of life without much care and then another 5-15 years where ongoing patching and repairs are needed.
The Advantage of Low Slope – Good Overhangs and Good LightThe one real advantage to a low slope roof is if the building also comes with large roof overhangs (where the plane of the roof hangs out past the walls of the house.) Some houses have low slope roofs with large overhangs and because the roof is low slope, the roof overhangs do not block your windows. This design affords good protection of the house and nice interior light. While you do have a generally higher-maintenance low slope roof, this should come with lower maintenance siding, windows, doors and decks as they are protected by the roof. This can be a great trade off. Contrast this with a pitched roof house that does not have the benefit of a roof overhang. Such a house may have the benefit of a sloped roof, but the increased maintenance costs for the exposed siding, trim, windows, doors and decks could far exceed the additional maintenance costs of a low slope roof. The bottom line: roof overhangs are your friend when it comes to reducing exterior maintenance.
The Advantage of a Pitched RoofPitched roofs are generally less expensive to install and last longer than low slope roofs. This is because shingle systems are easier to install than membrane systems and shingles cost less. This is a generalization that depends a great deal on the type of roofing material you install, but is a good guiding principal. My personal favorite pitch for a roof is a 5 and 12; this pitch sheds water well but is not too steep – you can still have good roof overhangs to protect the building and the roof is just shallow enough in pitch that you can walk on the roof to service it. Roofs steeper than 5 and 12 are difficult to walk on.
Watch Out for Complex Roof LinesA great guiding principal when looking at roof lines and maintenance is that complex roof lines are more likely to be a problem than simple roof lines. A complex flat roof may have lots of things stored on it like HVAC systems and duct work. It might have lots of penetrations like skylights and vents or intersecting roof plains like roof-to-wall junctures. Sloped roofs could have a myriad of intersecting planes, roof to wall junctures, deck intersections or valleys draining at the sides of the house. Be wary of complex roof lines whether sloped or low slope. Bottom line: When it comes to low maintenance roof lines, simplicity is your friend.
One of my favorite low-maintenance roof designs is the shed roof. This is just a single tilted plane of a roof and even if it is low slope, the design is usually so simple that problems are less likely.
In ConclusionYou would be wise to consider the relative benefits and drawbacks of various roof lines as you look at houses to buy. Do not underestimate the value of a good roof line. If low exterior maintenance is what you are looking for, seek homes with generous roof overhangs and simple roof lines.
Boyd Construction Co
Family owned and operated in the greater Washington DC area since 1932.