Quick answer
5-inch vs 6-inch gutters in Tacoma, WA: Most Tacoma homes handle about 40.8 inches of rain a year fine on standard 5-inch K-style gutters, because our rain is steady rather than intense. Step up to 6-inch when a single run drains more than about 2,500 square feet of roof, the pitch is steeper than 6/12, a valley dumps into one spot, or Douglas fir keeps packing the trough with needles. Pair 6-inch with 3×4 downspouts, or the outlets become the bottleneck. Call (253) 777-1572 or get a free sizing quote.
Start with the weather
The local rain math: lots of rain, not much intensity
Rainfall alone rarely decides gutter size in Pierce County. The way our rain arrives matters far more than how much of it there is.
Tacoma averages 40.8 inches of precipitation a year, a little wetter than Seattle’s 39.3, based on NOAA’s 1991 to 2020 climate normals. November is the wettest month at 6.5 inches. That sounds like a case for the biggest gutter you can buy, until you look at how it falls.
Those 6.5 November inches come across roughly 19 rainy days, about a third of an inch a day. Our rain is persistent, not violent. The City of Tacoma’s own surface water manual says the same thing: the 2-year design storm is 2.0 inches over 24 hours, and even a 100-year event is 4.1 inches over 24 hours.
That matters more than any other number here, because gutter capacity is a question of inches per hour, not inches per year. A Gulf Coast thunderstorm can drop two inches in an hour. Here, two inches takes a day. That is why 5-inch is honestly enough for a lot of Tacoma homes, as long as it is clean, pitched right and has enough downspouts.
So when a Tacoma gutter overflows, the first question is not whether the rain was too big. It is what else is going on: the roof feeding that run, the pitch, the outlets, or the debris in the trough. The rest of this guide goes through each one.
The real variables
Roof area decides the size, and pitch multiplies it
Gutters are sized to the roof area draining into each run, not to the square footage of the house.
How much each size holds
A 5-inch K-style gutter holds roughly 1.2 gallons per linear foot. A 6-inch gutter holds about 2.0 gallons, around two thirds more. At the one-inch-per-hour intensity the standard charts assume, a 5-inch run is rated for about 5,500 square feet of roof and a 6-inch for about 7,960.
Those numbers look generous until you divide the roof up, because what counts is the area feeding each run. One long gutter catching a wide roof plane with a single downspout at the far end is a different job than the same footage split across four runs. That is why two houses of identical size can need different gutters.
Pitch makes a roof act bigger
A steeper roof behaves like a larger one, because it catches more wind-driven rain and sheds it faster. These are the standard adjustment factors applied to roof area before sizing.
| Roof pitch | Add to roof area | What it looks like |
|---|---|---|
| Flat to 3/12 | No adjustment | Low-slope additions, porches, carports |
| 4/12 to 5/12 | Add 5 percent | Many ramblers and ranch homes |
| 6/12 to 8/12 | Add 10 percent | A typical two-story roof |
| 9/12 to 11/12 | Add 20 percent | Steep gables and many older craftsman roofs |
| 12/12 and steeper | Add 30 percent | Very steep gables, A-frames and tall dormers |
The aim problem the charts miss
There is a second effect on steep roofs. Water leaves the edge with real speed and can shoot straight over a narrow trough. That is not an overflow problem. It is an aim problem, and no amount of cleaning will fix it. A 6-inch trough is wider at the top and catches what a 5-inch throws past. If you see water arcing past the gutter in a hard rain while the trough itself is not full, this is what you are looking at.
The maddening one
Why a perfectly clean 5-inch gutter still overflows
Cleaned in September, spilling over the front edge in November anyway. Usually one of three things is going on.
The trough is losing depth to debris
Under Douglas fir and big-leaf maple, needles and seed pack into a dense mat. A 5-inch gutter carrying an inch of packed needles has lost a big share of its capacity, and it did not take long. A 6-inch gutter under the same tree still has usable depth. In Tacoma, debris tolerance is the most common real reason to size up, not rainfall. We explain how each kind of debris fills a trough in what is really filling your gutters.
The water is landing in one spot
Roof valleys funnel a large area into a narrow stream that hits the gutter in one place. That spot overflows while the rest of the run sits half empty. The fix is usually an outlet near the valley, not a bigger gutter along the whole house.
The outlets cannot keep up
A gutter is a holding channel. Downspouts are the drain. Get the drain wrong and the size of the channel stops mattering. A 2×3 downspout handles roughly 600 square feet of roof, and a 3×4 handles about 1,200, roughly double. One downspout per 40 feet of run is the common minimum, and under heavy tree cover every 30 feet is the better target. Valleys and inside corners usually justify one of their own.
Here is the pairing that matters most: 6-inch gutters on 2×3 downspouts create a bottleneck. The trough fills faster than the outlets can empty it, and you have paid for capacity you cannot use. Six-inch belongs on 3×4, which is why the two upgrades are quoted together. And a 3×4 is harder for needles and cedar sprays to plug.
Signs your house is a 6-inch house
- A long, wide roof plane drains into one run with a single downspout at the end.
- The roof is steeper than about 6/12 and water shoots past the front edge in hard rain.
- A valley dumps into the middle of a run and that spot overflows every storm.
- Firs or cedars hang over the roof and the trough loses depth within weeks of a cleaning.
- The existing gutter overflows even right after a cleaning, with the downspouts flowing.
- You are replacing the gutters anyway, so the upgrade costs only the difference.
Putting it together
A gutter sizing guide for Tacoma homes
Treat this as a starting point, not a verdict. Tree cover, valley placement and fascia condition can move a house a row in either direction.
| Roof area feeding one run | Pitch | Typical Tacoma call | Downspouts |
|---|---|---|---|
| Under 1,200 sq ft | Up to 6/12 | 5-inch K-style | 2×3, one every 30 to 40 ft |
| 1,200 to 2,500 sq ft | Up to 6/12 | 5-inch is usually fine | 3×4, or more 2×3 outlets |
| 1,200 to 2,500 sq ft | Steeper than 6/12 | 5-inch, or 6-inch under conifers | 3×4 |
| 2,500 to 4,000 sq ft | Any | 6-inch K-style | 3×4, one every 30 ft |
| Over 4,000 sq ft, or commercial | Any | 6-inch, sometimes 7-inch | 3×4 or larger |
When 5-inch is still the right answer
Plenty of Tacoma homes do not need the upgrade, and we would rather tell you that than sell it. A one-story or modest two-story with roof planes under about 1,200 square feet, a moderate pitch, enough downspouts and no conifer overhead will do fine on 5-inch seamless aluminum for decades. And 6-inch will not fix the wrong problem. If gutters overflow because the pitch is off, the hangers have loosened, or there are three downspouts where there should be six, a wider trough just gives the water a bigger place to sit. Correcting slope, adding outlets, rehanging on hidden hangers through our gutter repair service, or adding a BroGuard fine mesh guard is often the better use of the same money. Diagnose first. Larger buildings sometimes call for 7-inch gutters, which we cover with our commercial gutter work.
K-style or half-round?
K-style is the standard here for a reason. It holds a lot more water than a half-round of the same nominal width, which is why a 5-inch K-style is rated for roughly twice the roof area of a 5-inch half-round. Half-round is mostly chosen on historic homes for the look. Our gutter styles page shows the difference.
The piece of metal nobody quotes: the gutter apron
One part matters almost as much as gutter size and almost never comes up in a quote: the gutter apron. It is the flashing that carries water off the roof edge into the trough instead of letting it wick back onto the fascia. Without it, you can get rot behind a gutter that drains perfectly. In a climate that keeps roof edges wet for months, ask whether yours has one.
How we size your house
- Measure the roof planes.We figure the area feeding each run, not the footprint of the house.
- Note the pitch.Steeper planes get the adjustment and a look at overshoot.
- Count the valleys.Each one is a concentrated stream that may need its own outlet.
- Look up at the trees.Firs and cedars overhead shift the call toward more depth and 3×4 outlets.
- Check the fascia and apron.The edge has to be sound before any size goes on it.
- Recommend a size in writing.Often it is 5-inch, and we say so.
For the money side, our guide to what new gutters cost in Tacoma covers what the size decision does to the price. When you are ready, see our gutter installation service.
Not sure if your house needs 5-inch or 6-inch? Call (253) 777-1572
Get a Free EstimateFrom the crew: before you pay to size up, stand outside in a hard rain and watch where the water goes. Overflow along the whole run points to capacity or debris. Overflow at one spot points to a valley or a missing outlet, and that is usually a much smaller fix.
Frequently Asked Questions
Most homes need 5-inch K-style. Step up to 6-inch when a single run drains more than about 2,500 square feet of roof, the pitch is steeper than 6/12, or heavy conifer debris keeps cutting into the trough’s depth. The roof area feeding each run matters more than the size of the house.
Sometimes, but rainfall intensity is rarely the reason here. Tacoma’s 40.8 inches a year arrive at moderate intensity across many days. The stronger local reasons for 6-inch are large or steep roof planes and constant fir and maple debris, which eats into a 5-inch trough’s usable depth much faster.
A 2×3 downspout drains roughly 600 square feet of roof and a 3×4 drains about 1,200, close to double. A 3×4 also clogs less easily on needles and cedar sprays. Six-inch gutters should always be paired with 3×4 downspouts, or the outlets bottleneck the extra capacity.
One per 40 feet of run is the common minimum. Under heavy tree cover, every 30 feet is the better target, and roof valleys and inside corners usually justify an outlet of their own.
Only if capacity is the real problem. If the pitch is off, the hangers are loose, a valley needs its own outlet, or there are too few downspouts, a wider trough just holds more standing water. Diagnose the cause before paying for the bigger size.
Yes, and they are the standard here. K-style holds much more water than a half-round of the same nominal width, so a 5-inch K-style is rated for roughly twice the roof area of a 5-inch half-round. Half-round is mostly chosen on historic homes for its look.
Free estimates
Ready for gutters sized to your Tacoma roof, not a guess?
Free, no-pressure written estimates from local Solutionists. We measure every roof plane, place the downspouts where the water goes, and form seamless 5-inch or 6-inch gutters on site, cut to the exact length of each run.
The Brothers That Just Do Gutters · Tacoma · (253) 777-1572 · Serving Tacoma, WA and the South Sound
Licensed, Bonded & Insured · Washington Contractor License #BRTHRBT745J1