Case Study Overview
How Rimkus Delivered Assessment, Tendering, and Construction Administration for a Full Window and Balcony Door Replacement at an Occupied 284-Unit High-Rise Condominium in Mississauga, Ontario
Rimkus Building Sciences is providing full-scope consulting services for window and balcony sliding door replacement at a 284-unit occupied high-rise condominium in Mississauga, Ontario: preliminary assessment and report, design and specification, competitive tendering, contract administration, and ongoing construction field reviews. Five bids were received and a competitive contract of $6,165,400.00 (excl. HST) was awarded. Construction is progressing through four phased stages, with 17 field reviews completed as of March 2026, interior finishing ongoing, and a final deficiency inspection in preparation.
Who this is for: Residential condominium corporations, property management companies, and building owners planning full window or balcony door replacement programs on occupied high-rise buildings requiring independent assessment, specification, competitive tendering, construction administration, and mockup performance testing.
What We Did
- Conducted a preliminary site assessment of existing windows and balcony sliding door assemblies across all 284 units, documenting existing conditions, dimensions, and deficiencies to inform design and specification development.
- Prepared design documents, specifications, and tender drawings; managed a competitive tender process resulting in five bids from six invited contractors; recommended award to the lowest qualified bidder.
- Is providing ongoing construction administration including 17 field reviews across four phased construction stages, observed mockup air infiltration and water penetration testing, administered one construction change order, and is preparing a final deficiency inspection.
How We Helped
- Managed a competitive tender that produced five bids with a spread of over $1,012,800 from lowest to highest, demonstrating the value of a structured tender process over informal quotation. The recommended contractor’s base bid of $5,787,200 (excl. HST) was $479,500 below the second-lowest submission.
- Observed third-party mockup air infiltration and water penetration testing at unit 102 prior to full-scale installation. Both the window and balcony door assemblies passed testing to the required AAMA/WDMA/CSA 101 standards, confirming product performance before installation proceeded across the building.
- Provided independent field review of installation quality across all four construction phases — documenting correct anchorage, membrane application, sealant installation, and interior finishing work — and directed corrective actions as required throughout the program.
|
SERVICE LINES |
SECTOR |
LOCATION |
ENGAGEMENT LEAD |
|---|---|---|---|
|
Building Sciences |
Residential Condominium |
Mississauga, Ontario |
Marc Winters, P.Eng. — Rimkus BES, Canada |
|
284 |
17 |
5 |
4 |
|---|---|---|---|
|
UNITS |
FIELD REVIEWS |
BIDS RECEIVED |
PHASES |
What Was the Challenge? End-of-Life Windows and Balcony Doors on an Occupied High-Rise
A 284-unit high-rise residential condominium in Mississauga, Ontario required full replacement of its existing window and balcony sliding door assemblies across all units. The building, a mixed one-bedroom and two-bedroom high-rise, required a comprehensive program encompassing assessment, engineering design, competitive tendering, and multi-phase construction administration on an occupied site.
The core challenge was managing a replacement program of this scale on an occupied residential building: coordinating swing stage access across multiple construction phases, maintaining interior protection for residents throughout installation, verifying that new window and door assemblies met specified performance requirements before full-scale installation, and administering installation quality across 284 units from the ground floor to the upper floors.
The property management company retained Rimkus Building Sciences to provide the full scope of consulting services: from preliminary condition assessment through design, tendering, construction administration, and final deficiency inspection.
“A full window replacement program on an occupied 284-unit high-rise requires performance testing before full-scale installation proceeds, phased access planning, and independent field review at every stage. On this project, Rimkus observed mockup testing, managed four construction phases, and completed 17 field reviews.” – Chander Thusu, B.Eng., BSS, Practice Leader, Building Sciences
Services Provided: Assessment Through Construction Administration
Rimkus Building Sciences provided the full lifecycle of consulting services for this window and balcony door replacement program.
Preliminary Assessment and Report |
Design Documents and Tendering |
|---|---|
|
Conducted a detailed site assessment of existing window and balcony sliding door assemblies at the property, reviewing all 284 units from accessible vantage points. Documented existing conditions, dimensions, and deficiencies; developed design rationale and remediation options including recommendations on glazing specifications; and provided preliminary construction budget estimates using RS Means cost data, supplier, and contractor cost information. |
Prepared design documents, full specifications, and tender drawings. Issued four addenda during the tender period. Managed the pre-bid site meeting, received and evaluated five bids from six invited contractors, prepared a bid summary letter with analysis and recommendation, and issued a letter of intent to award to the recommended contractor. |
Construction Administration and Field Reviews |
Occupied-Site Coordination |
|
Provided ongoing construction administration from mobilization through the current phase IV installation, including 17 field reviews across four construction phases. Observed third-party mockup air infiltration and water penetration testing. Administered one construction change order. Is currently preparing a final deficiency inspection questionnaire to be circulated to residents before selective unit inspections. |
All construction work was administered on a fully occupied residential building. Field reviews documented contractor adherence to PPE requirements, interior floor protection for residents, pedestrian safety hoarding and sidewalk protection canopies, and safe swing stage setup and operation across all four construction phases. |
The Tender Process: Five Bids, Competitive Spread, and Award
Rimkus managed a competitive tender process for the window and balcony sliding door replacement program. Six contractors were invited to submit bids; five bids were received.
|
Contractor |
Base Bid (excl. HST) |
Total (excl. HST) |
|---|---|---|
|
Maresco Limited |
$5,787,200 |
$6,539,536 |
|
Wall Savers Ltd |
$6,266,700 |
$7,081,371 |
|
Can Mar Contracting Limited |
$6,395,400 |
$7,226,802 |
|
Langstaff Restorations Limited |
$6,710,000 |
$7,582,300 |
|
AT AJS Contracting |
$6,800,000 |
$7,684,000 |
Rimkus reviewed all bid submissions in a bid summary letter dated April 8, 2025, and recommended award to Maresco Limited as the lowest qualified bidder at $5,787,200.00 (excl. HST). The spread from lowest to highest bid exceeded $1,012,800, and Maresco’s submission was $479,500 below the second-lowest bid, reflecting the value of a structured competitive tender over informal quotation.
Following review of the bid analysis, a letter of intent to award was issued on April 23, 2025. The awarded contract included the base bid plus additional scope items: Item D1.6 ($598,450.00) and Item E1.3 at 50% discount ($59,750.00), less two material credits negotiated with the contractor: a credit for no use of Willseal 600 ($150,000.00) and a credit for a glass substitute (Cardinal 272 low-E coating in lieu of the originally specified crystal grey tint, $130,000.00). The resulting contract price subtotal was $6,165,400.00 (excl. HST), with a total contract value of $6,966,902.00 (incl. HST).
Mockup Testing: Air Infiltration and Water Penetration Performance Verification
Before full-scale installation proceeded across the building, the contractor installed a mockup window and balcony sliding door assembly at unit 102. Rimkus observed third-party air infiltration and water penetration testing conducted by JRAMCO on July 21, 2025.
Testing was performed to the following standards:
- Air Infiltration: AAMA/WDMA/CSA 101/I.S.2/A440-08 (Canadian A3 rating), tested to ASTM E783-02 at 75 Pa pressure differential.
- Water Tightness: AAMA/WDMA/CSA 101/I.S.2/A440-08 and A440S1-09, tested to ASTM E1105-15 at 330 Pa pressure differential.
Both the window and the balcony sliding door assemblies passed air infiltration and water penetration testing. JRAMCO issued field test reports FT25-360-0718-01 and FT25-360-0718-02 on August 19, 2025. Rimkus confirmed the mockup met specified performance requirements before installation proceeded across the remaining units.
Construction Administration: Four Phases, 17 Field Reviews
Construction was organized into four phases, with swing stages positioned at successive drops across the building elevations. Rimkus conducted 17 field reviews from mobilization through the current phase IV exterior sealant work.
- FR 1 (June 23, 2025): Contractor removed existing window and balcony door assemblies at the ground-floor mockup suite. New Blueskin PE 200 HT air and vapour barrier installed along precast panel tops and upturns; BES 925 sealant applied at Blueskin lap joints. New AWD aluminum window frames positioned, leveled, and anchored with Ruspro-coated concrete anchors.
- FR 2 (July 21, 2025): Rimkus observed third-party air infiltration and water penetration testing on the mockup assemblies at unit 102. Both window and balcony door passed testing to AAMA/WDMA/CSA 101 standards.
- FRs 3 to 6 (September 2025): Full-scale installation commenced on phase I drops, with interior finishing crews working concurrently on lower floors. Exterior caulking planned for completion once all phase I drops finished.
- FR 7: Exterior sealant inspection on completed phase I drops.
- FRs 8 and 9: Phase II swing stage repositioned to drops 08, 09, and 10. Decorative lights found nailed to exterior sealant at one unit. Residents directed not to fasten anything to sealant, caulking, or window frames. Cracked IGUs from phase I noted; replacements ordered.
- FRs 10 and 11: Phase II installation and exterior sealant work continued.
- FRs 12 and 13 (December 3, 2025): Phase III commenced. Phase I and II installation confirmed 100% complete. Contractor advised to monitor temperatures for exterior sealant work and to follow manufacturer recommendations. Sidewalk protection canopy installed at east parking lot entrance.
- FRs 14 to 16: Phase III and phase IV installation progressed through drops 11, 12, 01, 02, 03, and 04.
- FR 17 (March 2, 2026): Phase IV exterior sealant work is in progress. Window and door installation is complete for this drop including ground floor. Interior finishing is ongoing and Rimkus is developing an online deficiency questionnaire for resident circulation prior to selective unit deficiency inspections.
Notes on Methods and Limitations
Field reviews are discrete site observations at defined milestones and do not constitute continuous inspection. The contractor remains solely responsible for on-site health and safety requirements, fire hazard management, construction techniques, and compliance with all applicable laws and regulations. Review comments are limited to construction results, means, and methods visible and being performed at the time of each visit.
Construction Change Order
One construction change order was issued for this project.
|
Change Order |
Date Issued |
Amount (excl. HST) |
Description |
|---|---|---|---|
|
CO1 |
July 4, 2025 |
-$339,750.00 (excl. HST); -$383,917.50 (incl. HST) |
Three credits formalized at contract execution: (1) credit for alternate low-E glass coating (Cardinal 272 on surface #2 in lieu of crystal grey tint with low-E SN 68 soft coat); (2) credit for no use of Willseal 600 perimeter sealant; (3) 50% credit for exterior paint finish in Acrynar on Item E1.3 |
Key Observations and Corrective Directions
|
Observation |
Field Review |
Direction and Outcome |
|---|---|---|
|
Mockup assemblies required air and water testing before full-scale installation |
FR 2 (July 21, 2025) |
Third-party testing by JRAMCO observed by Rimkus; both window and balcony door passed to AAMA/WDMA/CSA 101 standards before installation proceeded |
|
Decorative lights nailed to exterior sealant at one balcony unit, risking early sealant failure |
FR 9 (October 24, 2025) |
Contractor directed to advise residents not to fasten anything to sealants, caulking, or window frames |
|
Cracked IGUs identified in phase I completed units |
FR 9 (October 24, 2025) |
Replacement IGUs ordered; contractor tracked delivery and scheduled installation |
|
Cold weather sealant installation: risk of installation on frost or wet surfaces |
FR 13 (December 3, 2025) |
Contractor directed to monitor weather conditions and outside temperature, and to follow manufacturer recommendations for all exterior sealant work |
|
All site-specific work plans and documentation required to be maintained on site |
FR 9 and FR 13 |
Contractor reminded to maintain all required site-specific documentation and to have safety coordinator inspect swing stage setup for each new phase |
Construction Administration Note: Observations on this project have been operational in nature: product performance was confirmed through mockup testing before full-scale installation, installation deficiencies such as cracked IGUs were identified and tracked for replacement, and resident-caused risks to newly installed sealants were documented and directed for communication. A final deficiency inspection is in preparation as of March 2026.
The Value Delivered
Full-scope consulting for a window replacement program of this scale delivers value at every phase: from structured competitive tendering through independent performance testing and phased construction oversight.
Competitive tendering returned measurable value. Five bids were received with a spread exceeding $1,012,800 from lowest to highest submission. The awarded contract at $5,787,200 (excl. HST) was $479,500 below the second-lowest bid. A structured tender with pre-bid site meeting, four addenda, and documented bid analysis supports the property management company’s decision with a written recommendation they can rely on.
Performance testing before full-scale installation reduced risk. Mockup air infiltration and water penetration testing confirmed that the specified window and balcony door assemblies met AAMA/WDMA/CSA 101 performance requirements before installation proceeded across all 284 units. Testing was conducted by an independent third party and observed by Rimkus, providing documented product performance confirmation.
Phased construction oversight on an occupied high-rise. Seventeen field reviews across four construction phases are providing independent verification of installation quality at every stage: anchorage, membrane application, sealant, interior finishing, and safety measures. Deficiencies were identified and directed for correction before subsequent phases proceeded.
Material credits negotiated at award reduced total contract cost. Two material substitutions identified during bid analysis were formalized as credits in Change Order 1: $150,000 for substitution of the Willseal 600 perimeter sealant and $130,000 for an alternate low-E glass coating, reducing the contract price by $280,000 (excl. HST) before construction began.
Why Rimkus Built Environment Solutions
Window and balcony door replacement on an occupied high-rise residential building requires a consultant who can manage the full project lifecycle: from condition assessment and specification development through competitive tendering, performance verification testing, and multi-phase construction administration. Rimkus Building Sciences provides independent oversight at every stage, giving property managers and condominium corporations a documented record of what was specified, what was tendered, what was tested, and what was installed.
We serve condominium corporations, property management companies, building owners, and institutional asset managers requiring technical consulting for window and building envelope replacement, building envelope condition assessment, reserve fund studies, and construction administration across high-rise and mid-rise residential buildings throughout Canada.
Key Takeaways for Condominium Corporations and Property Managers
Condominium Corporation and Property Manager Should Know About Window Replacement Programs
- Mockup testing before full-scale installation is essential for high-rise window replacement programs. Testing to AAMA/WDMA/CSA 101 standards confirms that the specified product meets air infiltration and water penetration requirements before installation proceeds across hundreds of units.
- Competitive tendering on a program of this scale can produce significant spread between bids. On this project, the spread from lowest to highest exceeded $1,012,800. A structured process with documented bid analysis gives the owner a defensible basis for award.
- Full-scope consulting services (assessment, design, tendering, and construction administration from a single consultant) provides continuity from specification intent through installation verification, reducing the risk that installation departs from what was designed.
- On occupied high-rise buildings, phased swing stage construction requires coordination with residents, interior floor protection, pedestrian canopy installation, and monitoring of exterior sealant work in cold weather conditions.
- A final deficiency inspection, conducted by the consultant after installation is substantially complete, provides the owner with a documented record of any outstanding work before contractor demobilization.
Related Services
- Building Sciences Consulting
- Window and Building Envelope Replacement
- Construction Administration
- Reserve Fund Studies and Condition Assessments
- Specification Writing and Tender Management
Frequently Asked Questions
Connect with Our Expert
Chander Thusu, B.Eng., BSS
Practice Leader, Building Sciences
+1 416 970 3107
[email protected]
View Chander’s Expert Profile
Chander has 32 years of experience in building sciences, structural rehabilitation of parking and balcony structures, and forensic investigation of high-humid buildings such as swimming pools and steam rooms. He holds a Building Science Specialist (BSS) designation from the Ontario Building Envelope Council and a Building Science Certificate from the University of Toronto.
This case study is intended to provide general information and insights into prevailing industry practices. It is not intended to constitute, and should not be relied upon as, legal, technical, or professional advice. The content does not replace consultation with a qualified expert or professional regarding the specific facts and circumstances of any particular matter.