Large-Radius Gutter for Hospitality and Hotel Exteriors

Why this matters

Hospitality projects (hotels, resorts, country clubs, restored historic inns, restaurants on landmark blocks) sit at the high end of the commercial gutter market. The owner is buying brand presence, not function alone. The architect specifies 6-inch and 7-inch half-round copper, soldered ogee in 16 oz copper, or radius-shaped fabricated profile that does not exist on any rollformer truck. Margins on this work are several multiples of residential K-style because the labor is specialty, the lead time is long, and the failure tolerance is zero (a copper drip stain on a stucco facade is a six-figure callback). This article covers the technical and contract envelope so a gutter contractor can quote and execute the work without leaving money on the table or eating a callback.

Profile and material specification

Half-round 6 inch or 7 inch in 16 oz copper is the most common hospitality specification. The half-round geometry sheds debris better than K-style, develops the soft patina the architect specified, and survives 75 years if soldered correctly. The 16 oz weight is the SMACNA minimum for permanent architectural work; 20 oz and 24 oz are upgrades for coastal or industrial-corrosion exposure.

Box gutter (rectangular cross-section, often integrated into a built-in cornice on historic facades) is specified in 20 oz to 24 oz copper or 0.050 lead-coated copper, fully soldered with expansion joints every 30 to 40 feet. SMACNA covers the joint detail and the cricket-and-drain geometry inside the box.

Ogee or custom radius profiles are fabricated on a press brake from flat copper coil at a sheet-metal shop. Lead time runs eight to fourteen weeks. Do not promise the GC a delivery date before the fabricator commits.

Soldering the joints

Lead-tin (50/50 or 60/40) solder with rosin flux is the standard for copper architectural gutter. SMACNA requires lapped, soldered joints (not crimped, not sealant-only) on copper and on lead-coated copper. The lap is 1 to 1.5 inches with the upstream piece overlapping the downstream piece in the flow direction.

Joint preparation: the lap surfaces are cleaned to bright copper with a non-chloride flux paste, tinned with a torch and solder before assembly, then sweated together. A properly tinned and sweated lap shows a continuous silver-gray solder fillet on both edges of the lap. A cold joint shows a granular surface and a discontinuous fillet, and it will leak inside two seasons.

Apprentices should not solder the visible joints on a hospitality job. The owner is paying for an artisan finish.

Hanger spacing and expansion

Concealed half-round hanger straps every 24 inches with a stainless steel screw into solid framing is the SMACNA recommendation for 6-inch copper. Copper expansion is 0.0000094 inch per inch per degree F. A 30-foot run swings about 0.34 inch from 0 F to 100 F; design an expansion joint every 30 to 40 feet on long runs and use slip-joint hangers, not fixed-pin hangers, between expansion stops.

Mixing copper with aluminum, galvanized steel, or pressure-treated lumber accelerates galvanic corrosion of the less-noble metal. Hangers must be copper or stainless steel; flashings touching the copper must be copper or stainless; treated-wood contact requires a sacrificial copper or rubber separator.

Conductor heads and leaders

Hospitality projects almost always specify a custom conductor head (decorative collector box) at every downspout transition. The conductor head is fabricated to a shop drawing, sometimes with the property's logo or crest soldered into the face. Round leader pipe (often plain round, sometimes corrugated round) in matching copper completes the system. Round leaders run 3 inches, 4 inches, or 5 inches in diameter depending on the flow rate.

Strap leaders to the wall at 8 to 10 feet on center maximum. Round leader straps are copper or stainless, never galvanized.

Bid envelope and contract structure

Hospitality commercial gutter work is almost always a subcontract under a general contractor on an AIA A401 subcontract form, with progress billing on AIA G702 and G703. The contract requires submittals (shop drawings, material certifications, finish samples, mockup), a schedule of values broken out by elevation, and warranties (1-year workmanship and the copper manufacturer's mill warranty).

Mockup: a 10-foot section of finished gutter, installed at grade or on the building, is the architect's pre-approval gate. Plan a paid mockup line item; do not eat the cost as bid prep.

References

• SMACNA Architectural Sheet Metal Manual, 8th edition (half-round, box gutter, soldering, and expansion joint details).
• Copper Development Association, Copper in Architecture Handbook (alloy selection, joint design, patina behavior).
• AIA Document A401 Standard Form of Agreement Between Contractor and Subcontractor.
• AIA Documents G702 / G703 Application and Certificate for Payment.