Box Gutter Repair

Box Gutter Repair in the South of the United States

The South raised whole main streets behind parapets. Keeping the gutters behind them dry is what we do all day.

Book my free survey

Survey and written report at no cost, a callback inside one working day.

What a box gutter is, and why yours leaks

A box gutter does not hang off the roof edge. It is built into the roof itself: a timber trough lined with metal or membrane, running behind a parapet wall or tucked between two roof slopes. Nearly every American building put up before 1950 with a flat front, and most commercial roofs since, drains through one.

That hidden position is the whole problem. A hanging gutter fails in public, dripping where you can see it. A box gutter fails inward. The trough floor rusts through or a joint opens, and the water takes the shortest path into the building: along a beam, down a wall cavity, out through a ceiling ten feet from the actual hole.

By the time a stain appears, the leak has usually been running for seasons. This is why we open every job with a survey rather than a sales pitch. Someone has to stand in the trough, meter the timber and find out which of the six classic failures is at work before any fix is worth pricing.

Surveying a box gutter behind a brick parapet on a commercial roof

The six ways a trough gives up

FailureWhat you noticeHow serious
Rust-throughBrown staining creeping along one ceiling lineUrgent, the trough floor is opening
PondingWater still standing in the trough days after rainSerious, rust and split joints follow
Joint splitA leak that only arrives with hard rainModerate when caught early, patchable
Parapet overflowDamp patches high on an outside wallSerious, masonry soaks from the top down
Blocked outletOverflow at one corner in a downpourSimple to clear, expensive to ignore
Sagging boardsThe gutter line visibly dips mid-runStructural, this is a rebuild conversation

Every survey checks all six, photographs what it finds and writes down which ones your roof actually has.

Lining options, with their honest lifespans

OptionExpected lifeRelative costWhen it is the right call
Folded metal liner40 to 60 yearsHigherSound timber, long straight runs, an owner who intends to keep the building.
EPDM rubber liner25 to 35 yearsMiddleAwkward shapes and junctions, or when the roof must be weathertight by tonight.
Liquid membrane10 to 20 yearsLowerBuying honest time on a trough that is tired but structurally sound.
Full rebuildThe next sixty yearsHighestWhen boards, bearers and liner have all given up at once.

The survey decides this, not the brochure. When a coat of liquid is the wrong answer we say so, and when it is the right one nobody will talk you into a rebuild.

Troughs we have stood in

The survey
The surveyMoisture meter, flashlight and a slow walk of every junction before anyone talks money.
Decay, found early
Decay, found earlyFifty quiet years look like this. Catching a trough at this stage is the whole game.
Folded metal liners
Folded metal linersGalvanized or stainless sections folded to the trough and locked over sound timber.
EPDM lining
EPDM liningOne rubber membrane, welded seams, no joints left for the frost to open.
Liquid membranes
Liquid membranesRolled wet onto a prepared trough, reinforced at every junction and outlet.
Outlets and grates
Outlets and gratesA new drain head under a leaf grate, because most floods begin at a blocked outlet.

Homes, mills and main streets

Houses with history

Victorians, foursquares and rowhouses hide their gutters behind cornices and crown moldings, exactly where a ladder inspection never looks. The trough is often original, which means a century of patches over the first liner.

We work from the roof, keep the cornice profile intact and match liner details to the age of the house. The neighbors notice fresh paint, not our scaffold.

Commercial roofs and old mills

Parapet gutters on flat commercial roofs feed internal downpipes, so one blocked outlet can put water through three floors of stock. Mills and warehouses add long spans and valley troughs measured in hundreds of feet.

We schedule around trading hours, document every finding for owners and insurers, and can put the trough on a standing maintenance rota so the next blockage never becomes a claim.

Four moves, one dry building

  1. 1

    Send the form

    ZIP code, what the gutter is doing, your name and number. Photos can wait for the survey.

  2. 2

    The roof survey

    We walk the trough end to end, meter the timber, photograph every junction and lift what needs lifting.

  3. 3

    The report and the quote

    One document: what is failing, what can wait, and what each fix costs. You keep it whichever way you decide.

  4. 4

    The repair or the reline

    Liner in, outlets flowing, and a hose test before the ladder comes down for the last time.

The price of a dry trough

JobTypical bracketWhat it covers
Roof survey and written reportFreeFindings, photos and prices, yours to keep.
Patch and joint repair$260 - $700Seam resealed or a liner patch, leak traced first.
Reline in folded metal$34 - $60 / lin ftNew metal trough liner over repaired boards.
Reline in membrane$22 - $42 / lin ftEPDM or liquid system, junctions reinforced.
Full trough rebuild$90 - $180 / lin ftNew boards, bearers, liner and flashings.
New outlet and leaf grate$320 - $850Drain head cut in, sealed and grated.

Length, access and how far the rot has traveled set the final number. The survey settles all three, and the survey costs nothing.

Asked from under a stained ceiling

How do I know my building has a box gutter at all?

If the roof meets a parapet wall, if the front of the building is flat with no gutter visible from the sidewalk, or if two roof slopes meet over a wall, water is running through a built-in trough. Buildings put up before 1950 nearly always drain this way.

Why is the stain ten feet from where you found the hole?

Because water is a traveler. It leaves the trough at the failure, follows a beam or a wall cavity, and only drops when it runs out of road. Chasing the stain instead of the source is how buildings end up with three patches and the same leak.

Can you reline the gutter without touching the rest of the roof?

Usually, yes. The liner sits inside the trough and is independent of the slates, shingles or membrane around it. We tie the new liner into the existing covering at the edges, and the rest of the roof never knows we were there.

Metal or membrane, which liner should I want?

The honest answer is the one that fits your trough, not the one with the best margin. Sound timber and straight runs favor folded metal for its lifespan. Twisting runs, many outlets or a tight budget favor rubber or liquid. The report prices what fits.

How disruptive is the work for the shop or offices below?

Less than a leak is. Nearly everything happens at roof level behind edge protection. Trading continues, and for occupied commercial buildings we sequence noisy cutting outside the hours that hurt.

What if you find the gutter boards are rotten?

Then the report says so, with photographs, and prices the rebuild as its own line. Nobody discovers a doubled invoice halfway through the job. Rot found at survey stage is a plan; rot found mid-reline is an argument, and we prefer plans.

6 failure modeschecked on every survey
4 lining routesmetal, rubber, liquid or rebuild
1 documentfindings, photos and price together
0 dollarsfor the survey and the report

The rooflines around South

Zoom in on the flat roofs and parapets; the link ledgers below name every community our surveyors reach from here.

Each state of the South, on our rounds

Cities that raised the South

Somewhere above these streets a trough is quietly rusting.

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