A roof coating is a thick liquid layer sprayed or rolled onto a roof that dries into a seamless, rubbery skin. On flat and low slope roofs in Tucson, it does two jobs: it keeps water out, and it shields the roof below from ultraviolet light. On a foam roof, the coating is the only thing protecting the foam. Keep the coating in good shape and the roof underneath can last a long time. Let it wear through and the sun starts destroying the foam.
Why coatings matter so much in Tucson
Tucson gets about 3,806 hours of sunshine a year, which is 86% of all possible daylight. It averages 158 days a year at 90 F or above, and it has hit 117 F. Few roofs anywhere face that much UV and heat. Coatings slowly break down under it: they lose thickness, turn chalky and eventually crack. The monsoon then tests whatever is left. Storms that start in early July can drop more than 2 inches of rain in a month, and water finds any spot where the coating is thin or split.
A white or light coating also reflects sunlight, so the roof surface stays cooler than a dark roof would. That can help the rooms under a flat roof feel less hot on summer afternoons.
Types of roof coating
Elastomeric acrylic
Water based and widely used over foam and other flat roofs. It is usually white and reflective. Acrylic does best on roofs that drain well, because water that sits on it for days can soften it.
Silicone
Holds up well to standing water and UV. It can be harder to recoat later, because many products will not stick to silicone. Ask the roofer what can go over it in the future.
Other coatings
Some roofs use urethane or other coatings, often as a base layer or on roofs that see foot traffic. The right choice depends on what is already on the roof.
Many Tucson homeowners ask specifically about elastomeric roof coating. Elastomeric simply means the coating stretches and recovers as the roof heats up and cools down, instead of cracking. Most coatings sold for flat roofs are elastomeric in some form.
Signs your roof needs a recoat
- The coating rubs off as white or gray powder on your hand (chalking).
- You can see fine cracks or crazing across the surface.
- Bare foam is showing through. Foam is usually tan or yellow and turns brown or darker as the sun damages it.
- Granules or embedded stone have washed away in places.
- Water pools in the same spots after every storm.
- You see blisters or soft spots when you look at the roof from a ladder.
- The last recoat was long enough ago that nobody remembers when it was.
If bare foam is exposed, call soon. Foam left uncoated through a Tucson summer can lose depth quickly, and a simple recoat may turn into foam repair.
What a proper recoat involves
A coating only lasts if it is applied to a clean, sound roof at the right thickness. A good roofer will:
- 1Inspect the whole roof for blisters, wet foam, cracks and damaged areas, and check drains and scuppers.
- 2Clean the surface to remove dirt, loose coating and chalk, so the new coat bonds.
- 3Repair the damage by cutting out bad foam, filling holes and sealing cracks before coating.
- 4Prime if needed, depending on the old and new coating.
- 5Apply the coating at the thickness the manufacturer specifies, often in more than one coat.
- 6Add granules where the system calls for them, to protect against foot traffic and birds.
Ask the roofer how many gallons per square (100 square feet) they plan to apply and what dry thickness that gives. A cheap recoat is often a thin one.
When a coating is not enough
A coating protects a roof that is still sound. It does not fix a roof that is saturated with water, badly blistered, or failing across large areas. Older Tucson homes are common: 52.5% were built before 1980. Many older flat roofs carry several layers of foam and coatings from past work. If moisture is trapped between those layers, the roofer may recommend removing them and starting fresh. See flat and foam roofs and roof replacement.
Best time to coat a roof in Tucson
Coatings need dry weather and the right temperature range to cure. Spring and fall are the most comfortable seasons for coating work in Tucson. Spring has the added benefit of getting the roof ready before monsoon season begins on 15 June. Many products have limits on how hot the roof surface can be during application, so summer work is often done early in the morning.
What a roof coating costs
Coating jobs are priced after a roofer measures the roof and checks its condition. The main factors are roof size, how much repair is needed first, the type of coating, how many coats are applied, and how easy it is to get onto the roof. Ask for a written estimate that names the product, the thickness and the repair work included. See roof costs in Tucson for more.
Questions to ask before you pay for a coating
- What product will you use, and is it compatible with the coating on my roof now?
- What thickness will it be once dry?
- What repairs are included before coating?
- What written warranty covers the work, and what does the manufacturer warranty require?
- What is your Arizona ROC license number?
Common questions
How long does a roof coating last in Tucson?
It depends on the product, the thickness and how well the roof drains. Ask the roofer for the manufacturer's rated life and recoat schedule for the product they plan to use.
Can you coat over an old foam roof?
Usually, if the foam is dry and sound. The roofer should first repair blisters and damaged spots, clean the roof and check that the new coating will bond to the old one.
Is a white roof coating worth it in Tucson?
A light coating reflects sunlight and keeps the roof surface cooler than a dark one, which is helpful with Tucson's heat. It also protects foam and membranes from UV.
Can a coating stop a roof leak?
It can seal small cracks and worn areas. It will not fix wet foam, failed flashing or damaged decking, which need repair before any coating goes on.