· by Michael Blair, Nashville's Gutters
A lot of the older houses in East Nashville, Germantown, Edgefield and the historic parts of Franklin do not have gutters hanging off the fascia at all. The trough is framed into the cornice itself, lined with sheet metal, and hidden behind the trim so the eave reads as one clean line from the street. These are box gutters, sometimes called built-in or Yankee gutters, and they work well for a century when the lining is sound. When it is not, the water they collect goes straight into the framing of the house, and the first sign is usually a stain on a ceiling indoors rather than anything you can see from the yard.
How a box gutter is built
The trough is a wooden box set into the top of the wall or the rafter tails, with the roof running down into it and the cornice trim wrapped around the outside. It was lined with whatever the builder had: terne-coated tin plate on many houses of that era, copper on the better ones, galvanized steel later, and on houses that have been worked on since, often a rubber or modified-bitumen membrane laid over the old metal. Water runs along the lining to one or two outlets, drops through a conductor head or a hole in the soffit, and leaves by a downspout.
Everything under that lining is wood that was never meant to get wet. On a hung gutter, a failed seam drips outside the house. On a box gutter, a failed seam drips onto the top plate of the wall, the rafter tails and the cornice blocking, and it can do that for years before anything shows.
Where they fail
Old metal linings rust through in the low spots where water and wet leaves sit, and soldered seams crack as the metal expands in August sun and contracts on a January night. Membrane relinings fail at their laps and at the outlet, where the rubber has to turn down into the drop. And many box gutters were built dead level or have settled that way, so water that should run to the outlet stands in the middle of the run instead.
The outlet is the other weak point. Box gutters often have fewer outlets than a modern hung system would, so one clog backs water up the whole length of the trough until it finds a seam or overtops the back edge into the roof deck.
- Water stains on an upstairs ceiling close to an outside wall
- Peeling paint or soft wood on the cornice or soffit below the trough
- Rust stains or drips at the conductor head or outlet
- Standing water in the trough a day after rain
- Plants or moss growing in the gutter line
Reline, restore or convert
If the wooden box underneath is sound, relining is usually the right answer. Soldered copper or terne-coated stainless lasts for decades and keeps the house looking the way it was built; a single-ply membrane costs less and goes in faster but does not last as long and needs its seams and outlet watched. Where the box itself has rotted, the rotten wood is cut out and rebuilt first, with the slope corrected toward the outlet while it is open.
The other route is to close the box, roof over it, and hang a half-round or K-style gutter on the fascia instead. That removes the risk of water getting into the wall, but it changes what the eave looks like. If the house is in one of Nashville’s historic or conservation zoning overlays, a change to the visible cornice may need review, so check with Metro Historic Zoning before committing to it. In other cities, ask the local codes or planning office.
Keeping one working
Box gutters need cleaning more often than hung ones because a clog does more damage. Twice a year is the minimum, and on a lot with big oaks or maples the timing matters: after most of the leaves are down, which in Middle Tennessee is usually well into November, and again in late spring after the seed and catkin drop. Clear the outlet and run a hose into it to make sure the downspout below is open all the way down.
While you are up there, look at the lining. Any rust spot, split seam, blister in a membrane or low spot holding water is worth fixing before the winter rains start, because a box gutter that leaks through a wet winter gives the framing months of water and very little chance to dry.