- Project Type: Evaluation, Design, Construction Administration
The Vital Structure:
Wood-Framed Envelope Failure
Issue
Several wood-framed 2-3 story buildings built between 2009-2014, using vinyl siding and accent-areas of thin-brick veneer were exposed to the severe environment of the New England coastline. The Owners reported evidence of water, snow and wind infiltration through roof eaves, soffits, walls, fenestrations, and chimney transitional areas. Interior finishes at spot locations were becoming stained, with leaks reported in some locations since original construction. Although moisture issues were reported at select buildings and concentrated building transitional areas, Vital Structures engineers used exploratory destructive testing to expose extensive and global deterioration-extending to structural components.
Diagnosis
Performed building envelope evaluation with targeted/representative exploratory test cuts, which revealed:
- Thin brick veneer wall assemblies were not a ventilated drainable wall cladding, but rather a thin-set mortar application over the OSB sheathing with integral weather-resistive barrier. Limited areas were found to have substantial moisture infiltration, rotted structural framing and insect infestation.
- A poorly sealed wall penetration was found to have led to substantial moisture infiltration, saturated insulation, rotted sheathing and rotted structural framing
- Chimney framing could be easily moved by hand, with inconsistent anchorage and substandard structural connection.
- Wood framed exterior decks were neither connected nor flashed properly to the building which caused extensive rot in wood framing/sheathing and corrosion of structural connections.
- The deck outer and perimeter support beams and posts were not consistently pressure-treated, and constructed incorrectly with inadequate metal connectors, missing fasteners, suffered from inappropriate load-path resolve, and experienced damaged support post conditions from rodent mastication and water infiltration.
Solution
Prepared a building envelope evaluation report and complete design documents, including structural framing and building envelope repairs. The design for the thin-brick veneer replacement areas utilized a back-vented thin-brick, veneer-weeped panel system.
The Client’s Result
To solve the issue, we:
- Removed exterior wood-framed decks and slider doors to address envelope flashing/weatherproofing deficiencies.
- Removed building exterior sheathing to replace deteriorated structural wall framing, corroded connections, and to install solid wood blocking between framing members to receive new deck ledger connectors.
- Removed exterior brick veneer from wall sections and chimneys, and replaced with a drained brick veneer panelized system.
- Added transitional flashings, improved self-adhered water resistive barriers, door sill pans, and window flashing improvements.
- Replaced or reframed exterior deck support beams and columns, connectors, and re-established proper load path.
- Reframed and improved chimney anchorage and framing systems.
- Replaced exterior siding, trim, roofing systems, and low-slope roofing under exterior decks.
- Improved roof and wall ventilation systems to help resist wind-driven rain infiltration.
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