The Haboob Effect
Last September, I inspected a Mesa home that had been through a particularly nasty monsoon season. The owners mentioned a haboob had hit their neighborhood hard in July. They'd cleaned the pool and moved on.
The HVAC told a different story.
Both the air handler filter and the return air filter were caked with fine dust. The homeowners had changed filters in June. Three months later, they looked like they'd been in place for years. That's what happens when a wall of desert dust hits your home at 40+ mph.
I checked the outdoor condenser. The coils were coated with dust and debris. Efficiency was compromised. The system was working harder than it should have been, running longer cycles to maintain temperature.
This is common after monsoon season. Even well-maintained homes take a beating from dust storms. I recommend replacing all filters immediately after any haboob and having the condenser coils professionally cleaned at least annually.
Roof Drainage Issues
Phoenix has a lot of flat and low-slope roofs. The Southwestern aesthetic. They work fine 95% of the year when it barely rains. Monsoon season is the other 5%.
I was inspecting a 2005 home in Chandler in late September. The sellers said the roof had never leaked. But when I got up there, I found ponding marks. Water had pooled in multiple areas, leaving mineral deposits and debris lines. One area still had standing water from a storm three days earlier.
Flat roofs are designed with drainage in mind, but they require maintenance. Drains clog with desert debris. Scuppers get blocked. The slight slopes that should direct water to drains settle and shift over time.
This roof hadn't leaked yet, but it was heading there. The ponding would eventually degrade the membrane. I recommended cleaning all drains and having a roofer evaluate the slope issues before the next monsoon.
Flash Flood Traces
Phoenix doesn't have traditional flooding the way river cities do. But monsoon storms drop enormous amounts of water in short periods. Streets become rivers. Washes that are dry 99% of the year turn into torrents.
A Gilbert home I inspected last October was in a neighborhood that backed up to a wash. Beautiful view most of the year. During monsoon, that wash had overflowed its banks.
The evidence was in the garage. Water staining on the walls about four inches up. The water heater base showed corrosion. The garage door weatherstripping had been replaced recently, probably after the flooding.
The sellers disclosed "minor water intrusion during monsoon." The inspection showed it was more than minor. The garage had taken on several inches of water. The question was whether it would happen again.
I recommended checking the city's flood zone maps and talking to neighbors about the wash's history. The buyers did, learned this was a 25-year flood event rather than an annual problem, and proceeded with better information.
Stucco After the Storms
Stucco is everywhere in Phoenix. It handles dry heat well. Monsoon is harder on it.
The cycle of extreme heat, then sudden moisture, then back to heat causes expansion and contraction. Hairline cracks that existed before monsoon can let water penetrate during heavy rains. That water then evaporates quickly in the desert air, sometimes leaving salt deposits or causing the stucco to spall.
Post-monsoon inspections often reveal stucco issues that weren't visible before. I look for new cracking, especially around windows and doors. Water staining at the base of walls. Areas where the stucco sounds hollow when tapped, indicating it's separating from the substrate.
A Tempe home I inspected had a dramatic example. A large section of south-facing stucco had cracked and was separating. The homeowner said it happened "during the summer." Translation: the monsoon moisture got into existing cracks and expanded them. Repair estimate: $4,500.
The Bright Side of Monsoon Timing
Here's the thing about buying a Phoenix home right after monsoon season: you get honest information.
Homes inspected in the dry months might hide drainage problems. The roof looks fine when it hasn't rained in four months. The yard slopes look acceptable when there's no water to test them.
October and November inspections in Phoenix show you what the monsoon revealed. If the home made it through August's storms without issues, that's meaningful data. If problems exist, you'll see the evidence.
I tell clients that fall is actually a good time to buy in Phoenix from an inspection perspective. You're seeing the home after its annual stress test. The surprises have already happened.