What is a box gutter?

A gutter with a square or rectangular section. On older homes it is often built into the roof edge and hidden; on commercial buildings it is often a large metal gutter between roof slopes or behind a parapet.

Can box gutters be repaired?

Yes. Small leaks can be patched or re-soldered, worn linings can be replaced, and rotten framing can be rebuilt before relining.

Should I replace built-in gutters with regular gutters?

It is often the lower-maintenance option, but it changes the look. On historic homes, check local preservation rules first.

Why is my box gutter leaking inside the house?

Usually the lining has cracked or an outlet is blocked, so water overflows inside the trough edge and into the wall. Have it inspected quickly to limit rot.

What are hidden gutter systems?

Gutters built into or behind the roof edge so they cannot be seen from the street. They give a clean look but need regular checks of their lining.

Materials

Box Gutters and Built-In Gutters: Repair and Replacement

Box gutters look like part of the building rather than something hung on it. That is their appeal and their risk: when a built-in gutter leaks, the water goes straight into the structure.

Updated 2026-10-26 · Gutter Fixing Editorial Team

A box gutter is a gutter with a square or rectangular section. The term covers two different things. On commercial and industrial buildings, a box gutter is often a large rectangular metal gutter set between roof slopes or along a parapet wall. On older houses, box gutters are usually built into the roof edge or cornice, hidden behind trim, so from the street you see a clean roofline with no visible gutter at all.

Hidden or concealed gutters are also used on modern homes for the same clean look. Whatever the style, these systems need more care than an ordinary hung gutter, because any leak drains into the wall or roof framing rather than onto the ground.

Types of box, built-in and hidden gutters

Built-in wood gutters: troughs framed into the cornice of older homes and lined with metal, roofing membrane or, on very old homes, nothing at all.
Yankee gutters: a New England style where the gutter is built on top of the roof near the eave, behind a wood strip.
Commercial box gutters: large rectangular steel, stainless or aluminum gutters on warehouses, schools and shopping centers.
Valley and parapet gutters: box gutters set between two roof slopes or behind a parapet wall, draining to internal downspouts.
Modern concealed gutters: metal gutters hidden within the fascia or soffit on contemporary homes.

Why built-in gutters leak

Most built-in gutters fail at the lining. Old metal linings, often terne-coated steel or copper, crack at seams and corners as the metal moves with temperature. Roofing membranes split where they are folded. Once water gets under the lining it soaks the wood behind, and rot spreads quietly into the rafters, the cornice and sometimes the wall. Signs include peeling paint and staining on the cornice, water inside the top floor walls, and soft wood at the eave.

Box gutters on commercial roofs often fail because they are undersized for the roof area, because outlets are blocked, or because there is no overflow. Water then backs up over the gutter side and into the building. Ice and debris in long low-slope gutters make this worse.

Fixing box gutters: repair, reline or replace

Option	What it involves	When it fits
Spot repair	Re-solder or patch a failed seam or corner	One leak in an otherwise sound lining
Reline	New metal or membrane lining fitted inside the existing trough	Lining worn out, but the wood structure is sound
Rebuild	Rotten wood replaced, trough rebuilt, then lined	Leaks have damaged the framing
Convert	Built-in gutter closed and a hung gutter fitted	Owner prefers lower upkeep and the look allows it

Converting a built-in gutter to a standard hung gutter is common and usually cheaper over time, but it changes the look of the house. On historic homes, or in historic districts, preservation rules may require the built-in gutter to stay. The gutter replacement cost page covers the price side of rebuilding these systems.

Lining materials

Copper and lead-coated copper are the traditional linings on historic homes and last a very long time when soldered by an experienced tinsmith. Single-ply roofing membranes such as EPDM or TPO are quicker to install and suit many built-in gutters. Liquid-applied coatings can buy time on a sound metal lining but do not fix one that is cracked or loose. Stainless steel and zinc are used on high-end commercial work.

Design points for commercial box gutters

Size the gutter and outlets for the roof area and the local rainfall intensity, not for a typical house.
Provide overflows, such as scuppers or overflow outlets, so a blocked outlet does not flood the building.
Allow for expansion on long runs with expansion joints.
Keep the gutter sloped to outlets; dead-flat gutters hold water and debris.
Plan safe access for cleaning, since commercial box gutters collect a lot of debris and need regular service.

Seamless box gutters

Some installers can roll-form box-profile gutters seamless on site in aluminum or steel. These are used on modern homes and light commercial buildings that want a crisp square look. They are hung like K-style gutters, not built in, so they avoid most of the leak risk of a true built-in gutter while keeping the shape.

Finding a box gutter contractor

Fewer contractors repair box gutters than install standard gutters. The work combines carpentry, sheet metal and sometimes soldering. Ask for photos of built-in gutters they have relined, how they will check the wood behind, and what lining they recommend and why. Contractors in our network who handle box gutter repair and commercial box gutters can inspect the system and explain whether a reline or rebuild is needed.

Looking after box and built-in gutters

Built-in gutters reward regular care more than any other type. Clean them at least twice a year, because shallow troughs and small outlets clog quickly. Check the lining after each winter for cracks, lifted seams and ponding. Keep the outlet strainers clear and make sure the downspouts below run freely. Inside the house, look at upper ceilings and walls near the eaves for any new stain. Catching a lining failure early can mean a seam repair instead of rebuilding rotten framing.

Historic homes and box gutters

On Victorian, Colonial Revival and Craftsman houses, the built-in gutter is often part of a decorative cornice with moldings and brackets. Repairs there should protect that trim. Good restorers remove only the boards they must, copy damaged moldings, and reline the trough so the cornice keeps its original look. Ask how they will match profiles and paint.