Jeff Bowlsby CCS, CCCA
Exterior Wall and Stucco Consultant
Licensed California Architect
“Stucco buckets” are anathema to stucco and should be avoided.
Visit the StuccoMetrics Reference Archives webpage for cited references and further information.
The term “stucco bucket" is a term that was coined in the construction forensics community, when the effects of weather-exposed, ground facing, outer soffit corner conditions caused cracked, stained stucco cladding and deteriorated, concealed horizontal framing.
Patent research: Not all soffit drainage screed flashing lath accessory components and subassemblies are patented and not all patented BMJS lath accessory components were produced or are currently available. Select BMJS lath accessory components and subassemblies are discussed.
The 1969 Arnett soffit drainage screed flashing lath accessory component and subassembly was the first to recognize the need and provide a solution for soffit corner drainage, and the first significant use of extruded aluminum lath accessories in the stucco industry. Several variations of this component are available in ventilated and non-ventilated configurations and this component has remained essentially unchanged since it was introduced to the market.
1969 Arnett Soffit Drainage Screed flashing
lath accessory component and subassembly
(Ventilated version depicted)
As early as 1972, the Superior Metal Trim Products Co. offered a soffit drainage screed flashing lath accessory component and subassembly as the “Drip Mould #5 – For soffits and foundations – FHA Approved”. Superior is no longer in business, and has been acquired by Stockton Products.
1972 Superior Co. #5 Drip Mould
Drainage Screed flashing lath accessory component and subassembly
(Image from the 1991 catalog)
In 2008 a patent was issued to Don Pilz for a soffit drainage screed flashing lath accessory component and subassembly. This component features a longer attachment flange as a flashing component with the WRB, a sloped drainage surface, an extended drip edge at the corner, and brown coat screed at the soffit surface.
2008 Pilz Soffit Weep Corner
Drainage Screed flashing lath accessory component and subassembly
A stucco bucket is a configuration of exterior stucco wall cladding located at the bottom of a vertical stucco wall, where the stucco and its WRB are continuous and wrap and return onto an adjacent stucco soffit surface. Water that does not drain out from behind the cladding can be trapped between the continuous WRB and the framed substrate support causing decay and deterioration of the substrate support. The condition can occur at locations such as exposed beams that support roofs, projecting bays and balconies, stair landings, recessed window and door heads, and soffit corners above recessed building entries. Soffit surfaces defined as weather-exposed surfaces (WES) are the most vulnerable.
Stucco Bucket 01: Stucco bucket under projecting weather-exposed wood framed soffit at bay window.
Stucco Bucket 02: Stucco bucket at weather-exposed metal framed soffit at wall recess.
Stucco buckets occurring at weather-exposed locations may trap water within the stucco cladding system and may damage concealed framing and the exposed cladding.
Stucco Bucket 03: Stucco bucket at weather-exposed dropped perimeter beam. Parallel crack and staining at horizontal soffit surface.
Technically, stucco bucket configurations can exist at weather-protected locations, but are generally not of concern at protected locations because the condition is not weather-exposed.
Stucco buckets often occur below long beams supporting shallow roof overhangs or balcony edges, or at exterior weather-exposed stair well landing edge beams. In these applications the stucco cladding panel area geometry easily exceeds Minimum Stucco Industry Standards, which may cause cracks that potentially contribute to water intrusion related concealed water-related damages.
Images courtesy of Christine Diosdado PE
Simpson Gumpertz & Heger, Inc.
Stucco Bucket 04: Stucco bucket at weather-exposed dropped perimeter beam below elevated walkway. Parallel crack on vertical wall and staining on exposed stucco surfaces.
Stucco buckets earned their description from the water containment effect of the stucco cladding system as if it were a bucket, where it wraps from a vertical wall onto an adjacent horizontal soffit surface, directing water into the soffit assembly. A stucco bucket configuration with continuous stucco and WRB, provides no mechanism for draining water contained within the vertical stucco wall assembly, to get out. The contained water may be held against framing members where it can cause concealed damage whether the framing is wood or metal.
The building code defines weather-exposed surfaces (WES), which are effectively all exterior building surfaces that are not weather-protected, in specific geometrical and dimensional configurations, by roofs, overhangs and perimeter soffit beams. WES can include the vertical wall surface above the soffit corner, the horizontal soffit surface contiguous with the soffit corner at dropped beams, stair landing edges, recessed window and door opening heads, soffit surfaces at recessed building entryways and similar conditions. At longer spanning beam soffit edges, water may collect and cause damage proximate to the center of the beam span resulting from normal beam deflection.
Stucco Bucket 05: Stucco bucket at weather-exposed dropped perimeter beam, the bullnose corner is a give-away. Parallel crack on horizontal soffit beam surface during water testing. Note water nozzle in background and water droplets at beam soffit crack.
Certain stucco bucket configurations can be exacerbated by adjacent weather-exposed construction that accumulates and directs water towards the stucco bucket, such as tube steel exterior stair support tubes or stringer beams bearing onto stair landing edges. Additionally, stucco panel areas at soffit beams and similar stucco bucket assemblies while small in area, frequently exceed the Minimum Stucco Industry Standards for stucco panel area proportions, potentially allowing cracks to occur that allow water entry into the stucco bucket assembly.
Stucco Bucket 06: Stucco bucket at weather-exposed stairway landing beam. Stairwell open to the sky, angled stair support tube directing water towards stair landing, with stucco bucket configuration below. Note water staining on exposed wood beam framing.
Stucco Bucket 07: Stucco bucket at weather-exposed recessed window head. This entire stucco soffit surface is a WES.
Complicating matters, building codes and Minimum Stucco Industry Standards do not recognize this condition, or contain requirements to address and avoid stucco buckets, even though they have been well-known in the forensics community for many years.
For proactively addressing stucco buckets, a variety of standard soffit drainage lath accessory or drainage screed flashing components are available as solutions. Soffit drainage screeds are available in all the typical lath accessory materials, in a range of profiles, for integration with the WRB, to function as a soffit corner drainage subassembly and direct water out of the wall assembly and divert it away from the soffit.
Stucco Bucket 08: Soffit drainage screed (no perforations) installed above weather-exposed recessed window head location.
Stucco Bucket 09: Weather-exposed stucco soffit surface at recessed window head location, with soffit drainage screed.
Stucco buckets are a significant and common problem in the stucco industry and are easily avoided. Products and methods for draining weather-exposed, ground facing soffit corners are readily available and should be provided at all stucco bucket conditions even if they are not required by building codes and Minimum Stucco Industry Standards.
Minimum Standard of care:
· Know the building code definition of a weather-exposed surface (WES).
· Protect WES at soffits with a continuous WRB.
Stucco Best Practices:
· Avoid WES soffit surfaces where possible with building design.
· Continuously ventilate soffit assemblies where possible to allow the assembly to dry out if water does accumulate within it.
· Provide a continuous, non-perforated, soffit drainage screed flashing at ground facing, weather-exposed outer soffit corners, as part of a soffit drainage subassembly integrated with the WRB, which provides a means for draining water out of the wall assembly, diverting water away from the soffit assembly.
· Recognize configurations of construction that exacerbate stucco bucket conditions and provide means of mitigating their effects, by reconfiguring them, or providing additional waterproofing, flashings, soffit drainage subassemblies or other means of drainage.
· At long horizontal narrow stucco panel areas such as at spanning beams, provide additional vertically-oriented SMJS subassemblies to define smaller panel area geometries, to minimize cracks that allow water entry into the stucco wall cladding system.
Consultation with licensed and experienced stucco professionals is recommended for stucco-related endeavors. No liability is accepted for any reason or circumstance, specifically including personal or professional negligence, consequential damages or third party claims, based on any legal theory, from the use, misuse or reliance upon information presented or in any way connected with StuccoMetrics.com.