Monsoon Roof Inspection Checklist (What to Walk Before Storm Season)
By Jonas Ruiz · Published May 18, 2026 · 12-minute read
AZ monsoon season starts June 15 and runs through September 30. The storms are not gentle. Microbursts routinely hit 70-90 mph in the Phoenix metro. Downpours that would take a week to accumulate elsewhere arrive in 20 minutes. Dust storms abrade anything exposed. The condition of your roof on June 14 is the condition it will be tested on when the first haboob rolls in. This checklist is the inspection routine we walk every May — organized by what you can check yourself from the ground, what requires a ladder (or a pro), and how to triage what you find.
Why Pre-Monsoon Timing Matters
There's a specific window — May 1 through June 10 — when repair scheduling is still manageable. Once the season starts, every contractor in the Valley is fielding storm-damage calls and scheduling gets tight. Materials lead times stretch. If you discover a problem during a July storm, you're calling into a queue that's already backed up from the previous week's event.
Pre-monsoon inspection in May means any critical work can be scheduled and completed before the season opens. That's the whole point. It's also when our calendar has the most availability.
A word on inspection frequency: AZ roofs should be walked at minimum twice a year. May before monsoon, October-November after the season closes. Foam roof owners should add a January walk for freeze-expansion issues in foothill and northern AZ properties. If you've skipped the last two or three cycles, be prepared for the May inspection to surface a list.
What AZ Monsoons Actually Do to Roofs
Before the checklist, it's worth understanding the specific failure modes. AZ monsoon damage isn't the same as general storm damage. The combination of extreme wind speed, concentrated rainfall, and repeated thermal cycling creates a specific set of vulnerabilities.
Microburst wind load
Phoenix-metro microbursts regularly generate surface winds of 70-115 mph. A 2021 event in Glendale recorded 85 mph sustained. At those loads, unanchored concrete tiles become projectiles, flashing pulls from deck screws, and unsealed penetrations funnel water directly into the attic. The failure mode isn't usually the tile itself — it's the attachment detail. Tiles set on mortar beds that have cracked. Flashing edges that were lifted slightly and never re-fastened. Hip caps that were never fully sealed. Monsoon exploits everything that's already loose.
Concentrated rainfall and drainage overload
Phoenix averages 7-8 inches of rain annually. A single active monsoon event can deliver 1-2 inches in 20-30 minutes. Roof drainage systems — valleys, scuppers, downspouts — are sized for expected flow rates. When actual flow is three or four times the design rate, any drainage bottleneck holds water. Valley debris accumulation, a clogged downspout, or a scupper outlet blocked by last year's leaves can convert a routine storm into a standing-water event that forces water under tiles and into the underlayment.
UV degradation and thermal shock
AZ receives roughly 300 sunny days per year and summer surface temperatures on dark roofing materials can exceed 175°F. Underlayment, caulk, and top coats all degrade faster here than in any other U.S. climate zone. A 15-year-old underlayment in Phoenix has been through UV and thermal stress equivalent to 25 years in the Midwest. The pre-monsoon inspection is partly about identifying materials that have crossed from "aging" into "failing."
What You Can Check from the Ground
Three checks that require no ladder and give you useful information before you ever call a contractor.
1. Walk the perimeter at sundown
Late afternoon light is the best natural light for reading a tile roof from the ground. Stand back far enough to see the full roofline and look at the horizontal tile courses. Tiles should run in straight, level lines. Any tile that's rotated out of plane, lifted at the front edge, or visibly out of alignment is a problem. On a concrete tile roof, a single slipped tile can break two adjacent tiles when monsoon wind vibration works it against its neighbors.
Walk the full perimeter. Hip sections, where tiles turn corners, are the most common location for mortar-bed failures. Ridge tiles should sit flush and level. Any that look proud of the line have likely lost their mortar adhesion.
2. Check gutters and downspout splash zones for granules
If you have asphalt shingle (common on older Phoenix homes and most Flagstaff properties), gritty gray or black material accumulating at the downspout outlet or in the gutter trough is shingle granule loss. Granules are embedded in the shingle surface to protect the asphalt mat from UV degradation. When they shed in volume, the mat is exposed and the shingle is nearing end of life. Light seasonal granule shedding is normal; heavy accumulation — enough to fill your palm from one storm — means the shingles are past their service life and won't survive another monsoon season without additional failures.
3. Inspect soffit and fascia from the ground
Water staining on the soffit (the underside of the roof overhang), peeling paint on fascia boards, or visible wood rot at the fascia line are signs of past or present leak activity. The soffit isn't the leak source — it's where water shows up after it's already traveled a distance through the roof system. The location of soffit staining helps you triangulate where on the roof to focus the closer inspection. A stain on the north soffit of a tile home usually traces back to a valley or penetration on the north face — not necessarily directly above the stain.
What Needs a Ladder (or a Professional)
Roof walking carries real injury risk — falls from residential roofs cause serious injuries annually. Beyond the safety issue, walking an unfamiliar tile roof incorrectly can crack tiles that weren't cracked before. AZ tile has specific load paths: you walk the tile near the butt (the thick lower edge), not the head, and you step between courses rather than directly on the lap. If you don't know the technique, you'll do damage.
Most AZ roofing contractors offer free residential inspections. That's the better move for most homeowners. But if you do go up, here's what you're looking for.
4. Penetration flashing condition
Every penetration through the roof deck — AC stacks, plumbing vents, exhaust fans, electrical conduit — has a flashing collar that seals the gap between the penetration and the surrounding tile or membrane. Flashing is typically galvanized steel, aluminum, or in newer installs, lead-coated copper. It fails at the sealant/caulk joint before the metal itself corrodes.
What to look for: caulk that's cracked, peeling, or has visible gap. Flashing edge that's lifted off the tile below. Rust staining or rust bleed on the flashing surface. On foam roofs, penetration flashings are embedded in the foam — look for separation at the foam-to-flashing interface, or blistering foam directly adjacent to the stack. These are the highest-probability leak locations on any AZ roof.
5. Valley condition and drainage
The valley is where two roof planes meet at a downward angle, forming a V-shaped channel. Valleys carry the highest concentrated water load of any roof section. In a heavy monsoon event, valley flow can reach rates the drainage system wasn't engineered for.
What to check: debris accumulation (leaves, palm fronds, decomposed tile mortar) that would create a dam. Evidence of water overflow marks on the valley metal beyond the tile edges — this tells you the valley has already backed up in a prior storm. Visible underlayment or felt between the tiles — which means the valley course tiles have lifted or slipped. On open valleys (where metal is exposed), check for corrosion at the center seam and at the lower terminus where the valley meets the gutter or eave.
6. Underlayment condition at hip and ridge
Hip and ridge tiles take the most UV exposure of any surface on the roof. They're also the most commonly re-worked sections during repairs, meaning the underlayment underneath has been disturbed more often. Gently lift a ridge cap or hip tile (carefully — use a pry bar without applying load to the adjacent tile surface) and look at the underlayment underneath.
Good underlayment: pliable, dark gray to black, feels flexible when you press a corner. Failed underlayment: brittle, cracks when flexed, light-colored surface showing UV bleaching, visible holes or tears. If the hip and ridge underlayment is failing, assume the underlayment under the main field tiles is in similar or worse condition — it just hasn't been exposed to the same UV concentration.
7. Foam roof top coat condition
If you have a spray-polyurethane-foam (SPF) flat roof — common on Phoenix homes with flat additions or full flat architecture — check the top coat for chalking, crazing, and thinning. The top coat is a sacrificial UV-protection layer; when it degrades, UV attacks the foam directly. Run your hand across the surface: white or gray powder residue transferring to your palm is chalking, which means the top coat is at or past its recoat threshold. Visible crazing — a spider-web pattern of surface cracks — means the top coat has already cracked through. These are recoat items, not replacement items, but they're time-sensitive.
Prioritizing What You Find: The Three-Bucket System
Every inspection produces a mix of findings that range from urgent to long-term monitoring. We sort findings into three buckets and give homeowners a written breakdown in the same format.
Bucket 1 — Critical: address before June 15
Active leak evidence anywhere in the structure. Missing tiles in volume (more than 1-2 isolated spots). Exposed underlayment across multiple sections. Visible deck damage (rotted or delaminated plywood visible from above). Completely failed flashing with open gap to deck. Any drainage obstruction that would cause certain ponding in a heavy rain event.
These problems will worsen significantly during the first serious monsoon event. Not "might worsen" — will. Schedule repair before the season opens.
Bucket 2 — Watch: monitor through the season, address in October
Lifted flashing edges with existing caulk still providing partial seal. Single cracked or broken tiles not at penetrations. Minor caulk degradation that hasn't opened. Granule loss on shingles without visible bare asphalt patches. Foam top coat chalking without crazing. These are real items that need attention, but the timing risk is lower. October-November is the right repair window — after monsoon, before the winter rains.
Bucket 3 — Plan: 1-3 year horizon
Roof system approaching or past 20 years without documented repair history. Underlayment at mid-life showing early UV fatigue. Foam system past 10 years without a recoat on record. These aren't emergency items, but they tell you a major scope — full re-roof, full reapplication, or significant underlayment replacement — is coming in the planning window. Use this season to get estimates and budget accordingly.
Pre-Monsoon Repair Scheduling: What We Actually Do
When we walk a pre-monsoon inspection, we produce a written scope that lists every finding by bucket, with photographs and a repair estimate for any critical or watch items. If there's no work needed, we tell you that — we're not going to manufacture a list. If there is work needed, we give you a clear priority and timeline.
Inspections in May and early June are free. We book them Mon-Sat. If we find work we can do, we'll schedule it. If the work is outside our specialty — a full replacement that's better handled by a dedicated re-roof crew — we'll tell you who to call.
One thing we see repeatedly: homeowners who know something is wrong but delay the call because they're not sure if it's urgent. If you're not sure, that's what the inspection is for. Call (602) 555-0101 and we'll tell you whether it's a bucket-1 or a bucket-3. You don't need to know in advance.
What to Avoid: Post-Storm Door-Knockers
Every monsoon season, wave after wave of out-of-state roofing crews descend on Phoenix neighborhoods the morning after a significant storm. They knock on doors, offer "free inspections," claim they "noticed damage," and push for same-day contract signatures. A significant percentage of these operations disappear with deposits before doing any work. The rest typically inflate damage scopes for insurance fraud.
We wrote a full breakdown on how to identify them: How to Spot Storm-Chaser Scams in Phoenix. Short version: don't sign anything at the door. Check any contractor's AZ ROC license at roc.az.gov before you commit. Call contractors you've researched yourself, not ones who knocked on your door.
Frequently Asked Questions
When does AZ monsoon season start and end?
June 15 through September 30. Peak activity is July through mid-August. Pre-season inspection work should be complete by June 10.
How often should I have my AZ roof inspected?
At minimum twice a year: May before monsoon and October-November after. Foam roof owners should add a January walk for freeze-expansion issues in elevated areas. After any major storm event — microburst, hail, heavy blow-in — a post-event inspection is worthwhile even if you don't see interior damage.
Can I inspect my own roof in Arizona?
Ground-level checks — perimeter tile scan, gutter granule check, soffit and fascia inspection — are useful and safe to do yourself. Walking the roof surface carries fall risk and can crack tiles if you don't know the load paths. Most AZ contractors offer free residential inspections. Use them.
What are the most common pre-monsoon findings in Phoenix?
Cracked or lifted flashing at AC stacks and plumbing vents. Underlayment degradation at hip and ridge. Slipped or cracked concrete tiles on steep-pitch sections. Deteriorated caulk at parapet walls on foam roofs. Valley debris accumulation. All preventable problems when caught in May.
How much wind do AZ monsoon microbursts actually generate?
Documented Phoenix-metro microbursts have produced 70-115 mph surface winds. The critical variable isn't average wind speed — it's the attachment details on your roof. Everything that's already slightly loose gets fully dislodged at those loads.
What is underlayment and why does it matter in Arizona?
Underlayment is the secondary water barrier installed directly on the roof deck, under the tiles or shingles. Tile is a weather shedding layer, not a waterproof layer — water regularly penetrates tile laps during heavy rain. Underlayment is what stops it from reaching the deck. In AZ's UV and heat environment, underlayment degrades faster than in other climates. Once it fails, there's nothing between a tile breach and your ceiling.
Does AZ monsoon rain really cause that much damage?
Yes. Phoenix gets 7-8 inches annually but can receive 1-2 inches in 20 minutes during a monsoon event. Any drainage bottleneck — clogged valley, blocked scupper, debris-filled downspout — creates standing water faster than the system can clear it. The damage comes from water forced under tiles by hydrostatic pressure, not from rain volume alone.