2.2.6 Roofing Projects

Evaluate the existing deck conditions to verify that the structure and all supports are in good condition.

• Perform the pull test check to determine structural deck can support uplift.

Review structural conditions, and finishes of soffits, canopies and associated columns identifying repairs where required.

Investigate and confirm conditions of existing metal flashings, sealants, and wall supports.

The existence of rooftop gardens is contingent upon the age of the building. Buildings constructed prior to 1980 typically do not include reserve capacity to support higher design live loads. If the rooftop space is required programmatically with CPS approval, verify the load requirements, and design the appropriate structural reinforcing with the structural engineer of record.

Roof replacements typically include the installation of additional insulation to meet current energy code requirements.

• Replace roofing system with new insulation thicknesses based on required R values. Make adjustments to existing curbs, window sill heights, parapet wall height, etc. to meet current City of Chicago code requirements for insulation thicknesses.
• Blown in insulation in roof attics is not an acceptable strategy for roof projects. However, if blown in insulation exists, it shall be examined for existing condition and included in determining the total R value when it is permitted to remain in place.
• In some instances, roof slopes are steep and an increase in insulation thickness on top of the deck will adversely affect existing parapet heights and detailing. Upon prior written approval by CPS, select areas may be determined to be exempt from the requirement to increase insulation thickness. All proposed adjustments related to this exemption are required to be very clearly identified and indicated on the related roofing drawings.

Roof renovations shall typically conform to new construction requirements for a modified bitumen roofing system. Existing standing seam metal, asphalt shingles, or other materials may be replaced in kind. For historical buildings, consideration of original design intent and appearance shall be maintained and/or restored.

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

• Investigative Masonry Openings are typically performed at major parapet elevations during envelope renovations including facade repa irs and roof replacements. Determine locations where openings are required to be provided for further investigation.
• Parapet Wall Rebuilds: Typically remove and replace the brick down to the top of the structural roof deck, below the finished roof level. AOR to determine the number of brick wythes for repair.
  • In many cases, the parapet scope is limited to the inner brick wythe of the parapet only.
  • Where only select replacement is required, new brick shall match and be toothed into old brick.
• Parapet Heights: Review parapet heights relative to the new required roofing insulation thickness. It may be required to raise the existing parapet height to accommodate the required insulation thickness. For roof renovation work, similar to new construction work, CPS has a full understanding of the recognized roofing industry standard for an 8 inch minimum mounting height for parapet and roof top accessory flashings, the CPS standard recognizes and goes beyond this industry standard and requires a minimum flashing dimension of 1’-2” for maintenance and performance enhancements to the roofing system.
• Parapet Wall Flashing: Parapet flashing and counter flashing shall be evaluated and repaired if deficient. If the parapet is being rebuilt or if the coping is being replaced through-wall flashing shall be provided above the parapet wall and under the coping, per CPS standards.
• Copings: Existing parapet copings are typically limestone, terra cotta or metal. Existing limestone or terra cotta that is in good condition may be salvaged for re-installation. Existing metal coping is typically removed, discarded and replaced with a new pre-engineered, factory fabricated, pre-finished aluminum system meeting ANSI/SPRI ES-1 wind loading criteria.
• Limestone Coping:
  • Damaged limestone coping units shall be replaced with new limestone units to match the existing units. New limestone units shall match the size and profile of the original.
  • Limestone coping joints shall be fully cut, cleaned and replaced with new tooled mortar followed by a final tooled sealant joint.
  • Stainless-steel through-wall flashing, stainless steel pins and sealant shall be installed at all new limestone coping units.
  • Existing limestone copings that do not have through-wall flashing shall typically be removed, salvaged and reset with the required stainless steel flashing and anchorage.
• Terra Cotta Coping:
  • Damaged overlapping terra cotta tiles shall be replaced with new overlapping terra cotta tiles to match the existing tiles. New terra cotta tiles shall match the size and profile of the original.
  • Existing overlapping terra cotta tiles that do not have through-wall flashing shall typically be removed, salvaged and reset with the required stainless steel flashing and anchorage.
• Terra Cotta Coping (Ornamental):
  • Slightly damaged ornamental terra cotta may be repaired by methods including, but not limited to, crack injection, patching of minor spalls and removal/resetting of displaced elements utilizing stainless steel ties to the backup structure.
  • Severely damaged ornamental terra cotta is generally not replaced with new ornamental terra cotta due to cost and lead time issues, unless there are unusual bas-relief details. For simple terra cotta profiles, new cut stone units may be provided to match and replace the original. More complex profiles may require replacement with new cast stone units. The new cut or cast stone shall be coated with an engineered coating to visually match the existing terra cotta when some existing terra cotta that will remain. All new through-wall flashings and anchorage shall be stainless steel.
  • Ornamental Terra Cotta Replacement In-Kind: When time and budget permit and there are significant ornate details, ornamental terra cotta is replaced with new terra cotta.
  • Existing Overlapping Terra Cotta Tiles that do not have through-wall flashing shall typically be removed, salvaged, and reset with the required stainless steel flashing and anchorage.
• The AOR shall review the existing limestone or terra cotta profiles and the new replacement limestone or terra cotta profiles to ensure that the new stone or terra cotta profiles match the existing conditions.
• Mortar Joints at Coping: Units shall be reviewed and repaired as required. Sealant shall be provided at skyward facing coping joints after tuck pointing
• Replacement Standards: When the parapet wall is found to be deficient, the coping may be salvaged and reinstalled following the reconstruction of the parapet wall. If more than 50% of coping is observed to be unsalvageable, complete coping replacement is required.

When there is not a need for historic or aesthetic consideration of the building and the existing coping requires replacement, existing metal coping shall be replaced with a new pre-engineered, factory fabricated, pre-finished aluminum system. Parapet height may need to be increased to ensure warranty requirements are met. To accommodate the necessary increase in height at existing low masonry parapets that requiring replacement, consider wrapping the new flashing membrane on top of the parapet wall prior to adding a new metal coping.

If a landmarked building cannot achieve warranty requirements for flashing based on the existing parapet heights, consider adding roof drains to reduce the total roof rise. This must be reviewed with CPS.

Existing window sill heights shall be coordinated with new roof membrane level. Where the existing sill heights do not meet the CPS standard 1’-2” height requirement for height, the sills must be raised for proper flashing detailing and the window must be replaced accordingly.

• The exterior trim and interior wall renovation shall be coordinated.

Verify the existing conditions of the curb height above the roof membrane and ensure that the curbs will continue to meet the CPS standard 1’-2” minimum height after re-roofing.

• Raised curbs heights shall be raised to a minimum of 1’-2” where non-compliant with CPS standard height. In no case shall they be less than the requirements for a manufacturer’s warranty.
• If abandoned roofed-over mechanical equipment curbs exist that are not integral with the existing roof structure, remove curbs, infill existing opening, as required with non-structure and deck to align with existing roof structure, and roof over with a new roofing system.
• Prefabricated curbs are preferred whenever new rooftop equipment is specified.

Increase ventilation stacks if they do not meet the CPS standard required height of 1’-2”.

Due to the potential for leaks, CPS prefers to remove existing skylights unless required for daylighting. If the Code requirements for natural light cannot be provided through windows, the optimal solution is to replace the existing skylight opening with a new light monitor.

• Demolish existing curbs at abandoned skylights and provide a new structural infill with appropriate structural framing and connections to match the adjacent roof height.
• Concrete curbs which are integral to the roof structure shall remain in-place.

For existing equipment planned to be removed and reinstalled, testing of existing equipment shall be made by the GC prior to removal. Testing and balancing of all systems removed or replaced during a roofing project is required to assure proper airflow and functionality. Provide baseline testing of equipment pre-design and pre-demolition to determine the sizing of equipment, establish areas served and minimize issues at project closeout.

• Identify the sequence of operation of equipment/components being temporarily removed/replaced and requiring demonstration of operation (post construction) for closeout. Any equipment determined unlikely to be functional upon re-installation shall be replaced. Typically, outdoor AHUs /RTUs are to be replaced after they are removed. Identify the need for curb adapters, curb scraping and painting.
• Equipment replacement is typically not included in a stand-alone roof replacement project. Salvage and reinstall equipment as applicable. Often the historic intake/relief hoods can be salvaged. If new roof equipment curbs are required, provide new prefabricated roof curbs accordingly.

Improper drainage, due to blocked and clogged roof drains may lead to leaks in the drainpipe or ponding water at the roof, resulting in water infiltration at the roof and/or walls. Evaluate existing conditions, locations, quantities, and functionality of all roof drainage components and assemblies.

• Roof drains shall be rodded and televised on all projects involving roof repair, roof replacement or other repairs to address water infiltration issues.
• AOR shall contract and provide a copy of a televising report (include video, findings and routing on floor plan/site plan with sizes). Review with CPS if new scope is identified through this process that was not indicated in OM.
• Adjust drains as required (typically drain pan) based on new insulation thickness and possible replacement if drains cannot be adjusted.
• For pre-finished or painted exterior gutters and drains, it has typically been more cost effective to replace than scrape and paint.

Secondary drainage plumbing shall be provided only where practical. Refer to Volume 4: Chapter 6.6 Roof Replacement Projects.

• When practical, replace primary drains with combination/overflow drains.
• If secondary (emergency overflow) drainage is not possible at existing/renovation construction, provide new parapet scuppers as a back-up to the primary drains.

Intake areas shall be reviewed to ensure that birds cannot roost within intakes. For large light and air well intakes, where a makeshift mesh screen has been installed, consider providing a structurally sound bird screen framing system to prevent any possible fall through the bird screen.

Field investigation of existing conduit runs shall be done to determine if existing conduit, piping, and ducts are serving active roof mounted equipment.

• Relocation is preferred for any conduit located on the roof or parapet which serves interior or exterior building lighting.
• Provide non-penetrating roof supports where conduit, piping and ductwork are to remain on the new roof surface.

Verify existing conditions. Exterior light fixtures and conduit that are mounted to a parapet wall shall be removed during a roof replacement project. Reroute all conduit and wiring in the attic space as required for proper installation of new wall mounted light fixtures. Provide new light fixture wall mounting details. No lighting is permitted to be roof mounted. Provide new wall mounted LED light fixtures per CPS Specifications.

Existing systems shall be evaluated and removed as required to allow for roof replacement work. EOR shall conduct lightning risk assessment to determine if a new lightning protection system shall be installed after roof replacement work is completed.

Coordinate the removal, storage, and protection during construction and re-installation after roof work is complete.

Coordinate with service provider for removal/replacement of existing equipment. The providers require long lead times for notice to modify their equipment. Work with CPS representatives to evaluate and coordinate the status of the equipment, to establish contractual requirements early in the design process.

• Cell equipment platforms commonly rest on parapet copings and penetrate parapet walls. Coordinate with the service provider to redesign required telecom equipment platforms to avoid bearing on parapets and to avoid wall penetrations wherever possible.

Various existing equipment, such as, cabling wires, shot spotter devices, security surveillance cameras, and abandoned equipment may exist on the rooftops or be mounted on parapets. Coordinate with the applicable CPS departments to determine if existing equipment is to remain or be removed. Provide appropriate notation regarding the existing equipment on the construction documents.