2.2.2 Exterior Masonry Renovations | Chicago Public Schools

Planning Rationale

The nature and extent of the masonry renovation scope is determined by the nature of the project intent, the construction type of the building and the condition of the building. The repair approach for a roofing project differs from a general renovation. The renovation scope shall typically be focused on the parapets and head walls.

Most buildings in the CPS inventory to be renovated are mass-masonry walls and require construction details and design elements to be consistent with the appropriate construction type. A smaller number of buildings are constructed with a brick veneer system.

When evaluating a building the nature of the underlying causes of distress shall be determined to establish the repair/renovation scope that shall be implemented. Existing conditions at the buildings vary widely. Issues may manifest themselves as brick spalling, efflorescence, cracking, displacement, discoloration, staining, and deteriorated mortar joints. For all new and renovated Exterior Masonry Construction, refer to the New Construction Guidelines: Volume 3, Chapter 2.1 Construction.

Typical Considerations for Exterior Masonry Renovation shall include, but are not be limited to the following:

Exterior Wall Construction

Confirm multiple wythe solid construction or cavity wall construction and note depth/ extent of damage depending upon construction type. Masonry wall opening inspections shall be performed to determine the condition of any questionable areas prior to completion of design. Scope shall address:

Areas of cracked masonry, including step and through-brick cracks shall be visually reviewed by the AOR to confirm the repair scope. A determination shall be made as to whether or not further destructive investigation is required.

Through-brick cracked masonry shall be rebuilt. The depth of the rebuild shall be based on the existing wall construction (e.g. mass masonry should receive two-wythe rebuilds and veneer should receive a single wythe rebuild).
Step-cracked masonry shall generally be tuck pointed unless there is significant displacement between the bricks.

Quantify locations where control joints, expansion joints, sill joints will be required. Detail locations where additional joints shall be cut in to address cracking. All control joints must be cut through the entire depth of the wall, including parapets and coping. Sealant and backer rod shall be installed on both sides of the walls. Parapet coping joints shall be fully cut, cleaned, and replaced with new tooled mortar followed by a final tooled sealant joint. All masonry joints that are not control or expansion joints, shall be filled with mortar.

Exposed Interior Brick at Exterior:

There are CPS buildings that include exterior exposed masonry that was formerly interior masonry, such as clay tile or interior brick, exposed at the facade. This occasionally occurs at sites where a portion of an older building was demolished leaving previously interior partition walls exposed to the exterior elements. This type of construction is not typically suitable to remain as an exterior wall and shall be considered for replacement or modification during a renovation project.

The extent of tuckpointing is based on the existing conditions. It is not always necessary to tuckpoint the entire building and may be cost prohibitive to do so. Identify general locations and percentage of each wall requiring repairs. The tuck-pointing scope at the facade shall be identified on the elevations of the documents.

If 50% or greater of a given wall elevation or building requires tuckpointing, then tuckpoint the wall or building in its entirety to maintain a consistent appearance of mortar and performance across the entire elevation. When 50% or more of the total building requires tuckpointing, tuckpoint the entire building provided the budget can cover the full quantity.
For areas indicated to be tuckpointed, remove and reinstall all wall mounted elements that are not part of the wall and would otherwise interfere with providing quality tuckpointing work.
Grinding depth shall normally be two times the joint thickness.
Art installations found to have been directly applied to the masonry are typically removed and not replaced. The AOR shall assess/document the existing conditions. However, AOR to coordinate with CPS prior to the start of construction. The ultimate scope of work should be approved by the CPS Capital Team and Principal. Refer to Public Artwork Installation on CPS Property requirements for further details.

Identify the conditions of windows, louvers, and door heads. Extent of repairs or replacement shall be determined and scope of work shall address damages to both the exterior surrounding facade and the associated interior finishes. Each elevation shall be documented to outline the scope of the work.

Investigative Openings: Select investigative masonry openings are typically performed at sample/select window heads. Investigative openings allow the AOR to confirm the hidden steel elements primarily for the condition of the steel lintels and not for the condition of the brick masonry. The AOR shall confirm the number of wythes of masonry required to be replaced to accommodate the extent of repairs or replacement of lintels.
Steel Lintels: Based on existing conditions, lintels shall be scraped and painted. If lintel replacement is required, install galvanized steel lintels with stainless steel flashing, end dams and drip edge.
- Deficient hung window head elements shall be replaced with new bottom-bearing lintels and stone window heads to match the existing color, size and profile of the window heads.
- Terra cotta: Damaged terra cotta is typically replaced with new coated engineered stone to reduce costs and meet schedule. The AOR should be aware of the lead times associated with procuring new terra cotta should replacement in-kind be desired. Scope for the cleaning and pointing of the overall terracotta material shall be developed for each specific project.
- Brick masonry hung lintels where there is evidence of corrosion (rust-jacking) cleaning shall be scoped.
Stone Lintels: True stone window head elements should be reviewed by the AOR.

Often, masonry is found to be infilled without being properly tied back to the building structure. For areas of replacement and infill, the exterior wythe shall be toothed into the adjacent masonry and tied to a backup structure such as CMU or mass masonry. The backup structure shall be fastened to the main building structure.

Infills: Infills at locations of original fenestration shall generally be constructed to match the color, texture and joinery pattern and profile of the adjacent existing masonry.
Abandoned Lintels: Many previously infilled locations include abandoned steel lintels and brick that was not toothed in. Abandoned lintels shall be removed when masonry infills are repaired.
Arches: Where arched openings are a significant architectural feature of the facade, the arch shall remain, and brick can be inset rather than toothed in. The brick must be tied back to the existing structure.

Typical repairs for non-brick facade elements such as terra cotta or stone elements include crack injection, patching of minor spalls and removal/reset of displaced elements with ties to the backup structure. Severely damaged units are typically replaced.

Damaged Stone: Existing stone shall be replaced with new stone to match the existing conditions.
Terra Cotta Replacement with Stone: Terra cotta is generally not replaced with new terra cotta due to cost and lead time issues unless there are unique bas-relief details. New stone shall be provided to match the existing terra cotta size and profile. The new stone shall be coated to visually match the existing terra cotta when some existing terra cotta will remain. Refer to the window head section on previous page.
Terra Cotta Replacement in Kind: Occasionally, when time and budget permit, terra cotta is replaced with new terra cotta, particularly when there are significant ornate details.
Profiles : The AOR shall review the existing terra cotta profiles and original to ensure the new stone or terra cotta pieces match the existing conditions.

Wall mounted equipment shall be coordination with the existing coursing, particularly when items need to be recessed.

Wall Mounted Receptacles: Existing receptacles shall be detailed in the documents, and not left to the building trades to locate. Include lockable covers on all exterior wall mounted receptacles.
Aiphone at Visitor Entry Door: Verify that school has a proper remote entry system with Aiphone and automatic door opener. For new installation and mounting heights refer to the exterior door section in Volume 3, Chapter 2.2.2 for additional information.
Automatic Door Operator : Coordinate mechanical and electric elements with masonry design.

Roof masonry generally refers to parapet walls and can also refer to facades which abut the roof. Areas of severe distress or displacement may require full rebuilding of walls.

Investigative Masonry Openings: Investigative masonry openings are typically performed at major parapet elevations during envelope renovations, including facade repairs and roof replacements. Determine locations where openings will need to be made for further investigation.
Parapet & Wall Rebuilds: Typically remove and replace brick down to the top of the structural roof deck, below the finished roof level. AOR to determine the number of wythes for repair.
- In many cases, the parapet scope is limited to the inner wythe of the parapet only. Where walls abut the roof, the top of the rebuild shall minimally extend to the top of the counterflashing.
- Where only select replacement is required, new brick shall be toothed into old brick.
Height of the Parapets: The parapet height shall be increased, as required, to minimally ensure that a warranty can be provided and that ideally the flashing height of 1’-2” (14”) minimum is provided above the finished roof surface per new construction standards. These heights shall be based on new insulation thickness at roofing system high points.
Flashing/Counterflashing: Flashing and counter flashing at the parapet walls shall be evaluated and repaired if deficient. If complete replacement of parapet or coping is required, then provide new throughwall flashing, above parapet wall and under the coping.
Copings : Parapet copings are typically limestone or terra cotta units but can also be metal. Typically, existing limestone and terra cotta that are in good condition are salvaged for re-installation and metal coping is removed, discarded and replaced with new assemblies
- Limestone and terra cotta copings:
  - Cracked and spalled coping units shall be repaired, but severely damaged copings shall be replaced with new units.
  - New coping pieces shall match the size and profile of the original. Terra cotta coping pieces are not typically replaced in-kind due to cost and lead time issues.
  - Stainless-steel through-wall flashing, and pins shall be provided at all coping units. Existing copings that are otherwise in good condition but do not have through-wall flashing, shall typically be removed, salvaged, and reset with appropriate flashing and anchorage.
  - Metal Coping: New metal roof copings and fascias are to be pre-engineered, factory fabricated, and made of pre-finished aluminum. Copings and roof edge flashing are required to be tested (not field tested) and certified in accordance with ANSI/SPRI ES-1 wind pressure criteria.
  - Mortar Joints at Coping : Units shall be evaluated and repaired as required. Sealant shall be provided at skyward facing coping joints after tuck pointing.
Complete Parapet Replacement: Replace a parapet in its entirety when at least 50% of the parapet requires repairs.

Equipment & Conduit:

CPS does not permit equipment, such as lights or conduit to be mounted to parapet walls. Existing parapet-mounted equipment, such as lighting, shall be removed and mounted to the exterior facade. Conduit shall be re-routed to the attic space.