Appeal 35019

N1101.2.3

The City of Portland Code Guide, N1101.2.3, mandates the installation of exterior insulation on the foundation walls of conditioned basements to meet modern energy efficiency standards. The intention of this code is to reduce thermal bridging and improve the overall energy performance of the building envelope.

We request an exception to this requirement, specifically asking for the omission of any non-permeable exterior insulation systems on the subterranean and near-grade historic brick foundation walls.

Instead of exterior insulation, we propose to achieve and exceed the code’s energy efficiency goals by treating the conditioned basement as a complete thermal unit, focusing on air sealing and insulating at more critical and appropriate locations. Our proposed design includes:

Fully Conditioned Space: The basement is and will continue to be a fully conditioned space, integrated into the home's HVAC system with dedicated supply and return air, along with a whole-basement dehumidification system to maintain a relative humidity below 50%.

Rim Joist Insulation: All rim joists at the top of the foundation wall will be meticulously air-sealed and insulated with closed-cell spray foam (or rigid foam board sealed in place). This is the single most significant point of heat loss in a basement, and our approach will address it directly.

Interior Surface Treatment: The interior face of the brick foundation will be cleaned and, if necessary, coated with a high-quality, vapor-permeable silicate paint. This will control brick dust and spalling without trapping moisture within the wall assembly.

Our request is based on established building science principles for historic masonry. Old brick foundations function as a complete system, and altering one part can have severe negative consequences.

A. Moisture Management and Vapor Permeability:
Historic brick and lime mortar are highly porous materials. They are designed to absorb moisture from the surrounding soil and release it to the exterior (or interior) air, allowing the wall to "breathe" and dry out. Applying a non-permeable exterior or interior insulation traps this moisture within the brick. This moisture cannot escape, creating a permanently damp masonry wall.

B. High Risk of Freeze-Thaw Damage (Spalling):
Portland's climate includes numerous freeze-thaw cycles. When moisture trapped inside the brick freezes, it expands, exerting immense pressure on the clay structure. This process, known as spalling, causes the face of the brick to pop off and disintegrate. Over time, this will destroy the structural integrity of the foundation. Insulating on the exterior keeps the brick cold while trapping moisture, creating the perfect conditions for catastrophic spalling.

C. Concealment of Structural Issues:
A bare brick foundation is its own best diagnostic tool. It allows for the immediate visual inspection of cracks, efflorescence (a sign of moisture intrusion), and mortar joint decay. Covering the foundation with an exterior insulation and finish system (EIFS) or other cladding completely conceals the foundation, allowing minor issues to become major structural failures before they are ever detected.

D. The Conditioned Basement as a Superior Energy Solution:
By fully conditioning the basement and thoroughly insulating the rim joists, we are effectively moving the building's thermal boundary. The earth surrounding the basement provides a natural, stable insulating value (approximately R-1 per inch of soil), with ground temperatures remaining relatively constant year-round. The primary source of energy loss is through the rim joists to the cold outside air. The rim joists are covered and insulated via a ceiling existent in the basement.

R106.1.1

Oregon code requirement is 36 inches for stair width and 30 inches for existing stairs.

Stair Width- The stair width to upstairs measures 29-32inches base stairs(Wall to foundation- 29 inches) to top of stairs(Wall to outside wall-32 inches). Inspector informed me that the standard size is 36 inches. Due to exterior stairs of the unit meeting code, there is no need for this stair to be compliant. Additionally any rectification here would mean adjusting the foundation or external wall which is not feasible.The home was built in1890 as a result

Leave as is. As it has been in existence since the home was built in1890

Any rectification here would mean adjusting the foundation and load bearing walls on the first floor which is not feasible. The home was built in1890 and the stairs are just used for walking up and down.