Gutters & Downspouts / Blog / Guide
What size gutters does a Portland house need?
Most Portland houses do well with 5-inch K-style gutters, and larger or steeper roofs, or roofs with long runs into one corner, need 6-inch. The right size comes from the roof area draining to each gutter, the roof's pitch, and how many downspouts carry it away, not from a single rule for the whole house.
How sizing works
- Roof area per gutter. Measure the roof plane that drains to that gutter, not the floor area of the house.
- Pitch. A steep roof sheds water faster and catches more wind-driven rain, so it counts as more area.
- Rainfall intensity. What matters is the hardest short downpour, not the yearly total. Portland gets a lot of rain, but most of it is steady; sizing is for the heavy bursts in fall and winter storms.
- Downspouts. A gutter is only as good as its outlets. More or larger downspouts let a 5-inch gutter handle a roof that would otherwise need 6-inch.
Signs your gutters are too small
- Water shoots over the gutter at valleys and inside corners, even when clean.
- Overflow only in heavy rain, not in drizzle.
- One downspout serving a long run of roof.
If your gutters overflow in steady rain too, the cause is more likely a clog or lost slope; see why gutters overflow.
Gutter styles we install
| Style | What it is | Fits |
|---|---|---|
| 5-inch K-style | The most common gutter, with a flat back and a curved face like crown molding | Most single-story and many two-story houses |
| 6-inch K-style | The same shape, bigger | Large or steep roofs, long runs, valleys dumping into one spot |
| Half-round | A rounded trough | Older and traditional houses, where the round profile suits the style |
| Fascia gutter | A smooth, flat face that looks like part of the fascia board | Modern houses, or where you want the gutter to blend into the roof edge |
| Wide-bottom fascia gutter | A fascia gutter with a wider trough | Bigger roofs that need more capacity with the fascia look |
Downspouts we install
| Downspout | Pairs well with |
|---|---|
| 3-inch round | Half-round gutters |
| Plain square | Fascia gutters and modern houses |
| 2x3 corrugated | 5-inch K-style on smaller roof areas |
| 3x4 corrugated | 6-inch K-style, and any gutter draining a big roof area |
A bigger downspout, or one more downspout, often fixes overflow without changing the gutter size.
The roof edge matters as much as the size
A gutter has to sit where the water comes off the roof, with the drip edge lapping into it. Too low, and water runs behind it. If the roof edge needs work, our Siding & Roofing site covers it.
Get it measured
We measure each roof plane and downspout run and size the gutters to them, then put it in a written estimate.
Our work is covered by a 2-year workmanship warranty, in writing.
Get a free gutter estimate or call Tim, (503) 597-8520.