Comparison
5-inch vs 6-inch gutters.
The most common question we get asked at an estimate, and the one where a default answer costs people money in both directions.
Short answer
Five-inch suits most standard single-storey Valley homes with straightforward rooflines. Six-inch is the right call when a large roof area drains toward a single run, when the pitch is steep, or on long runs — which in practice means most larger tile-roofed homes. Size it to the roof, not to a preference.
Side by side
| 5-inch K-style | 6-inch K-style | |
|---|---|---|
| Water capacity | Adequate for most standard rooflines | Substantially higher |
| Typical use | Single-storey tract homes, shorter runs, simple roofs | Large roof areas, steep pitch, long runs, a lot of roof draining to one place |
| Downspouts | Usually paired with 2x3 or 3x4 | Usually 3x4 |
| Appearance | Slimmer profile, less fascia covered | Covers more fascia, reads closer to trim |
| Cost per foot | Lower | Higher |
| Clog tolerance | Less forgiving — smaller channel fills faster | More forgiving with Arizona debris |
Why Arizona changes the calculation
Gutter sizing is driven by rainfall intensity, not annual total. Phoenix gets roughly eight inches a year, which is very little — but nearly all of it arrives in short monsoon bursts rather than spread across the seasons.
That means the system has to be sized for the burst, not the average. A gutter that would be comfortably adequate for the same house in a wetter but gentler climate can overflow here, because the peak flow rate is what matters and the peak arrives all at once.
Tile roofs push the same direction. Tile delivers water to the edge faster and more concentrated through the pan courses than shingle does, and tile is the Valley default on most homes built in the last thirty years.
When bigger is genuinely wasted money
Six-inch is not automatically better. On a modest single-storey home with a simple roof, short runs and adequate downspouts, five-inch handles the load and costs less per foot.
Upselling everyone to six-inch is easy and we would rather not. If five-inch is right for your house, that is what we will quote.
The factor people forget: downspouts
Capacity is a system, not a trough. A six-inch gutter feeding an undersized or badly placed downspout will still back up, because the restriction is downstream.
The number of downspouts, their size and where they are placed matter as much as the gutter profile. If a quote specifies gutter size but says nothing about downspouts, that is a gap worth asking about.
The verdict
Which should you choose?
- Choose 5-inch if you have a standard single-storey home, a straightforward roofline, and no single run taking a disproportionate share of the roof.
- Choose 6-inch if you have a large or steep roof, long runs, a tile roof shedding fast to few outlets, or a history of overflow at the corners.
- Either way, make sure the downspout sizing and placement were actually considered rather than defaulted.
Questions
Can I mix sizes on one house?
Does six-inch look bulky?
Is six-inch worth it just for fewer cleanings?
Want this decided for your actual roof?
We size to the house in front of us rather than to a default. Free estimate.