Porch Roof Gutters: Decks, Screened Porches and Sunrooms
Porch roof gutters are the gutters most likely to give trouble on a Columbus house. Many 1990s–2010s two-stories in Westerville, Hilliard and Gahanna have a deck out back, and plenty of those decks later got a screened porch or a three-season room built on top. Each addition changes how the gutters on that side of the house have to work. Often the porch was built by a deck builder, and nobody thought much about the gutters.
Why porch roofs are different
A low-slope porch roof drains slowly
Screened porch and sunroom roofs are often 2/12 or 3/12, so they fit under the second-floor windows. A low-slope porch roof sheds water slowly, holds snow longer, and lets leaves settle. On a shallow roof, water clings to the shingle edge and can run back under it instead of dropping into the gutter. That makes the gutter's position and a proper drip edge more important here than anywhere else on the house.
The main roof drains onto it
Often the upper trough on the back of the house ends right above the porch, or it was taken off when the porch went on. Either way, a big share of the back roof drains across the lower slope into one small trough at its edge. A 5-inch gutter with a single 2x3 downspout can't keep up with that much roof in a July storm. The water spills onto the deck, runs to the sliding-door threshold, and can end up in the basement.
Snow slides onto it
In a thaw, the snow on the main roof lets go and drops onto the porch and whatever hangs along its edge. A slab of wet snow coming off a two-story roof can flatten a gutter and tear out screens. Snow sliding onto a porch roof is a cold-climate problem, and it shapes how the trough below it should be built.
The downspout has nowhere to go
The corner of the porch is usually also the corner of the deck. The downspout has to come down through the deck, along a post, or sideways along the fascia to a corner that's over open ground. Too often it just ends on the deck boards. Water drips through onto the patio below, and in winter it leaves a sheet of ice on the deck.
The fix for each
Low-slope roof: the gutter needs a proper drip edge. On roofs of 3/12 or less, a contractor will usually set the front lip of the gutter slightly below the roof plane so water drops in instead of skipping past. The downspout should be the same 3x4 standard as the rest of the house.
Upper slope draining across the porch: the best fix is a gutter on the upper eave with its own downspout, run down the house wall past the porch. Then the lower trough only has to handle its own small slope. Where the porch meets the wall right at the eave and an upper gutter can't go back, the lower one usually goes up to 6-inch with two 3x4 downspouts, sized from the square footage that drains into it. 5-inch vs. 6-inch shows how to do the math.
Snow slides: snow guards on the main roof above the porch are small brackets that hold snow in place until it melts, so it can't slide off all at once. A roofer or a gutter contractor can install them. On the porch gutter itself, heavier .032 aluminum and hidden hangers every 16–18 inches give it a much better chance of surviving a slide.
Downspouts through a deck: a downspout can go through a deck. A contractor will cut a clean opening, sleeve it so the deck boards can't crush the pipe, and carry it down to grade under the deck. From there it connects to an extension or a buried line that comes out past the edge of the deck. The other option is to move the outlet to a corner of the porch that's over ground, using a longer, slightly steeper run along the top. The one setup to avoid is a downspout that ends on the deck boards.
Screened porch gutters and sunrooms
Screened porch gutters take a lot of leaf litter, because porches tend to sit under the backyard trees. A screen or micro-mesh guard is worth considering there more than anywhere else on the house, and so is checking that the downspout isn't plugged before a storm.
Prefab sunrooms, the aluminum-and-glass kind sold across central Ohio, often have a small built-in gutter along the roof edge with a narrow outlet. It handles the sunroom's own roof and nothing more. If the main roof drains across the sunroom, you'll get sunroom gutter overflow in every hard rain however clean that little gutter is. The fix has to happen upstream, on the main roof.
What it costs
| Item | Typical Columbus range |
|---|---|
| Porch gutter, seamless 6-inch, with 3x4 downspout | $12 – $16 per foot |
| Re-hang porch gutter on hidden hangers, 16–18 in | $150 – $300 |
| Downspout through the deck, sleeved, to grade | $200 – $400 |
| Buried line from under the deck to a pop-up emitter | $300 – $700 |
| Snow guards above the porch, per 30 ft | $300 – $700 |
| Restore the upper gutter over the porch, with downspout | $350 – $700 |
A typical back-of-house fix, with a new 6-inch porch gutter, a downspout through the deck and a buried line out past it, comes to roughly $900–$1,800. If it's done as part of a whole-house replacement, most of the porch work gets folded into the per-foot price.
A ten-minute check from the deck
You can learn most of what matters before anyone climbs a ladder. Go out during a steady rain, or run a hose on the upper slope for a few minutes, and look for these:
- Water skipping the lip. If it sheets over the front edge in the middle of the run, the trough is too high under that shallow slope or the drip edge is missing.
- A waterfall at one spot. Overflow right below where the upper gutter ends means the back of the house is draining into a trough sized for a fraction of that water.
- Where the downspout ends. Follow it. If it stops on the deck boards, on the patio below, or at the corner by the basement wall, that is the first thing to change.
- Dents and a rolled front edge. These are the marks a snow slide leaves, and they tell you the hangers took a beating too.
- Screens and ceiling stains. A stained porch ceiling near the edge points to water running back under the shingles.
Questions to ask on the estimate
- Where will each downspout end, and how far from the foundation?
- What size trough and downspout are you quoting, and how did you size them?
- Is the upper eave getting its own gutter, or is the porch still taking that water?
- What hanger type and spacing, and what thickness of aluminum?
- If the downspout goes through the deck, how is the opening sleeved?
Compare written estimates line by line on those five points. Two prices that look far apart often turn out to be quoting different fixes.
Mistakes that show up a winter later
The most common one is leaving the downspout on the deck because it was easiest. The second is replacing the small trough with an identical one while the back of the house still drains into it, so it overflows the first July storm. The third is skipping the hanger upgrade, which is fine until the first big snow lets go.
While you're back there
When a deck-side downspout ends at the corner of the house, the water lands where the deck footings meet the basement wall, on clay. If the basement is wet on the deck side, check that downspout first. Downspouts and your foundation covers how far the water needs to go. A porch gutter that drips at the corner onto the deck stairs is a plain repair, typically $150–$250, and it's worth doing before the drip turns into ice on the top step.
Common questions
Does a covered deck need gutters?
Usually, yes. Without a gutter, all the water off the deck roof falls in a line along the edge, splashing the deck, eroding the ground and soaking the footings. A covered deck right next to the house also sends that water toward the foundation. A small seamless gutter and one well-placed downspout is an inexpensive way to prevent all of that.
Should a sunroom have its own downspout?
Yes. A sunroom or three-season room should drain to its own downspout that ends on open ground, not into a deck or onto a walkway. If the built-in edge gutter on a prefab sunroom has a tiny outlet, ask whether it can tie into a full-size downspout at the corner.
Where should a porch downspout drain?
Onto open ground that slopes away from the house, at least 4 to 6 feet out, or into a buried line that surfaces past the deck. It shouldn't end on the deck boards, on the patio under the deck, or at the corner where the deck meets the foundation.
Why does my porch gutter overflow when the main roof doesn't?
Usually because it's carrying water from the main roof as well as its own. If the upper gutter ends above the porch, or there isn't one, much of the back slope drains into the small one below. A low pitch and a single 2x3 downspout make it worse. The fix is either giving the upper eave its own gutter and downspout or upsizing the lower trough and adding a second downspout.
Need gutter work in Columbus?
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