Flat and foam roofs, 6 min read
Caring for flat and foam roofs in Arizona
Flat and low-slope roofs are common across the Valley, from older ranch homes to Pueblo-style houses and commercial buildings. A little regular care keeps them watertight and helps them last.
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The short answer
Flat and foam roofs last longest when water drains off quickly, drains and scuppers stay clear, and the protective coating is renewed before it wears through. Check the roof after monsoon storms and at least once a year, watch for ponding, blisters, cracks and bird damage, and keep foot traffic to a minimum. Recoating a foam roof on time is far easier than repairing foam that has been exposed to the sun.
How flat and foam roofs are built
Flat roofs are not perfectly flat; they have a slight slope so water can drain toward drains, scuppers or gutters. Common flat roof systems in Arizona include built-up roofs, modified bitumen, single-ply membranes and spray polyurethane foam, often called SPF or foam.
A foam roof is sprayed on as a liquid that expands into a seamless, insulating layer, then covered with a protective coating. The foam provides insulation and the waterproof body of the roof, but it breaks down quickly in UV light. The coating is what protects it, which is why coating care is the heart of foam roof maintenance. See our flat roofing page for more on each system.
Ponding water
Ponding is water that stays on the roof after a storm instead of draining away. A common industry guideline treats water that remains 48 hours after rain as ponding. In Arizona sun, small puddles often evaporate quickly, but repeated ponding in the same spot can wear coatings faster, collect dirt and debris, and add weight.
Ponding usually points to a low spot, a clogged drain or a roof that has settled. Small areas can sometimes be built up with additional foam or other material during a repair or recoat. Larger or deeper ponding areas should be looked at by a roofer to find the cause.
Drains, scuppers and canales
Water leaves most flat roofs through roof drains, scuppers (openings through the parapet wall) or canales, the decorative channels common on Pueblo-style homes. When these clog, water backs up and finds other ways into the building.
- Check drains and scuppers before monsoon season starts on June 15 and after major storms.
- Remove leaves, dirt, tennis balls, nesting material and other debris.
- Look for cracks or gaps where the scupper or drain meets the roof surface.
- Make sure water exiting a scupper or canale is directed away from walls and the foundation.
- Keep tree branches trimmed back so leaves do not collect on the roof.
Parapet walls
Parapets are the short walls that extend above the roof line on many flat-roof homes. They hide equipment and give homes their classic Southwest look, but they are a common source of leaks. Water can get in through cracked stucco on top of the wall, through gaps where the wall meets the roof, or through damaged parapet caps.
When you inspect, look at the tops of parapets for cracks and at the inside corners where the roof turns up the wall. On foam roofs, the foam and coating usually run up the inside of the parapet, and that transition should be smooth and intact. Stucco repair on the outside of a parapet may need a stucco contractor, while the roof side is roofer territory.
Coating wear and recoat timing
Coatings on foam and other flat roofs slowly wear away from sun, heat, weather and dirt. As the coating thins, it reflects less heat and protects less. Eventually the foam underneath shows through, often with a tan or orange color, and once foam is exposed to UV it starts to break down.
How often a roof needs a recoat depends on the coating type, how thick it was applied and how the roof is used. Many foam roofs are recoated every several years, and your roofer can give you a timeline for your specific system. The key is to recoat while the foam is still healthy. A timely recoat with an elastomeric coating is far less work than tearing out damaged foam.
- Chalky residue that rubs off on your hand is normal aging, but heavy chalking means the coating is thinning.
- Cracking or peeling coating should be repaired before water gets underneath.
- Any exposed foam should be covered as soon as practical.
- Annual checks make it easier to plan a recoat before damage starts.
Blisters
Blisters are raised, bubble-like areas in a roof surface. On foam roofs, blisters can form when moisture gets trapped or when the foam or coating loses its bond. On built-up and other membrane roofs, trapped air or moisture between layers can cause similar bubbles.
Small, stable blisters are not always an emergency, but they should not be ignored. If a blister cracks or is punctured, water can get in. A roofer can cut out the damaged area, let it dry if needed, and fill and recoat it. Do not cut blisters open yourself.
Bird pecking and other damage
Birds sometimes peck at foam roofs, leaving small holes or gouges. The soft foam under the coating is easy for them to dig into. Each hole is a place where water and UV can reach the foam.
Look for small pockmarks, especially near parapets, AC units and other spots where birds perch. Small holes can be filled and coated during routine maintenance. Hail and wind-blown debris during monsoon storms can also leave dents and punctures that should be sealed.
Foot traffic and rooftop HVAC units
Many Arizona flat roofs carry air conditioning units, evaporative coolers, solar panels and vents. Each one brings service visits, and service visits bring foot traffic. Repeated walking wears through coatings, and dropped tools or screws can puncture the surface.
- Ask HVAC technicians to stay on established paths and avoid dragging equipment.
- Walk pads can protect high-traffic routes to equipment.
- Check around HVAC units after service for screws, panels or debris left behind.
- Look at the curbs and stands that support equipment, and at the seals around ductwork and electrical lines.
- Evaporative coolers can drip or overflow; a leaking cooler can damage the roof over time.
When to call a roofer
Call for help if you see exposed foam, standing water that does not drain, cracked coating, blisters, stains on ceilings below a flat roof, or damage after a storm. We handle repairs and maintenance, recoats and replacements on flat and foam roofs. Call us at 602-548-3770. If we don't answer, leave a message and we'll return your call within 24 hours. For a general idea of what affects pricing, see our Roofing Cost Guide.
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Frequently asked questions
Still have a question? Call the office at 602-548-3770, Monday to Friday, 7 am to 5 pm.
How often should a foam roof be recoated?
It depends on the coating type, its thickness and how the roof is used. Many foam roofs are recoated every several years. An inspection can tell you how much coating is left and when to plan the next recoat.
What does it mean if I can see orange or tan foam?
It usually means the protective coating has worn through and the foam is exposed. UV light breaks down exposed foam, so the area should be repaired and recoated as soon as practical.
Is a little standing water on my flat roof a problem?
Small puddles that dry within a day or two are common. Water that stays longer, or ponds in the same spot after every storm, can wear the roof faster and should be looked at to find the cause.
Can a foam roof be repaired, or does it need to be replaced?
Many foam roofs can be repaired and recoated as long as the foam is mostly dry and in good shape. If large areas are wet or badly damaged, those areas or the whole roof may need to be removed and replaced.
Why are there small holes in my foam roof?
Birds pecking at the foam are a common cause, especially near parapets and rooftop equipment. Hail and debris can also cause punctures. Small holes can be filled and coated during routine maintenance.
How do I keep HVAC technicians from damaging my roof?
Ask them to use a set path, avoid dragging equipment and remove all screws and debris when they finish. Walk pads along common routes help protect the coating.
Should I clean my flat roof drains myself?
If you can safely reach the roof with a secure ladder and the roof is cool and dry, clearing loose debris from drains and scuppers is reasonable. If access is difficult or you are unsure, have a professional handle it.
Do flat roofs leak more than sloped roofs?
Not necessarily. A well-maintained flat roof with good drainage can perform very well. Flat roofs do depend more on clear drains and a healthy coating or membrane, so regular checks matter.
Let's take a look at your roof.
Call the office at 602-548-3770 to schedule an estimate, Monday to Friday, 7 am to 5 pm. If we don't answer, leave a message and we'll return your call within 24 hours.