Post-Construction Window Cleaning

Why this matters

Post-construction window cleaning is the highest-revenue per-job work in the window cleaning trade. A new construction home with 30 to 50 windows can yield significant for a single visit; a new commercial building can yield a significant cost. The work is also the most demanding: windows are typically caked with construction debris (paint over-spray, joint compound dust, mortar, silicone caulk smears, sticker residue). Standard window cleaning methods fail; specialized scraping, solvents, and patience are needed. A contractor who can deliver post-construction cleaning to the spec the general contractor requires becomes a trusted source for new construction; the relationships generate ongoing residential work after the construction phase ends.

When to perform

• After all construction is complete (verify with the GC; some contractors are still working)
• Before occupancy
• After other trades have cleared (no more drywall sanding, painting, etc.)
• After exterior facade work is complete (siding, paint, masonry)

Typical contaminants

Tools and materials

• Squeegees (multiple sizes)
• Strip washers
• Razor scrapers (1.5 inch and 4 inch sizes)
• Steel wool (#0000 grade only; for glass; no other grade)
• Adhesive remover (Goof Off, Goo Gone, citrus-based)
• Mineral spirits
• Plastic scrapers (for vinyl, paint, frames)
• Mild detergent
• Water spot remover (for hard water deposits)
• Brushes (small detail brushes)
• Microfiber cloths
• Buckets
• Drop cloths (catch scrapings)
• PPE: gloves, eye protection, knee pads, fall protection

Safety considerations

Post-construction work involves:

• Working at heights (use proper fall protection)
• Chemical exposure (solvents, paint solvents)
• Sharp scraping tools (cut hazard)
• Dust inhalation (especially during dry scraping)
• Slip hazards (wet glass, drop cloths)

Procedure for typical post-construction window

Step 1: Survey and quote

Before starting:

• Walk the site
• Count windows and assess condition of each
• Note any windows that are heavily contaminated
• Identify the GC's specifications (per panel? hourly? complete cleaning?)
• Quote per the GC's specifications

GC pricing typically:

• Standard residential: modest per window
• Commercial: modest per window
• Per-pane vs per-window: clarify in the quote

Step 2: Test cleaning method on a sample window

Each construction site has different contaminants. Test:

• Try standard wet wash; observe results
• If wash doesn't remove contaminants, try scraping
• If scraping doesn't work, try chemical solvent
• Confirm the right method before scaling to all windows

Step 3: Surface preparation

For each window:

• Wet the surface (loosens dirt; reduces dust)
• Scrape if needed (always wet; never dry)
• Apply solvent if needed (small amount; rinse promptly)
• Allow time for the contamination to soften

Step 4: Wash and rinse

After preparation:

• Wash with detergent solution
• Use the squeegee with the strip washer technique
• Rinse with clean water
• Dry with microfiber

Step 5: Detail work

Pay attention to:

• Corners (where contamination collects)
• Edges of frames (where caulking smears appear)
• Lower edges (water collects)
• Specific contaminants (sticker residue, paint dots)

Step 6: Inspect under good lighting

After cleaning each window, inspect under:

• Direct sunlight (reveals smudges and streaks)
• Off-axis lighting (reveals haze)
• Up-close inspection (catches missed spots)

Customer's inspection will be tough; theirs needs to find nothing.

Step 7: Document and walk-through

• Photograph the cleaned windows (after each significant section)
• Walk through with the GC or construction manager
• Address any concerns

Step 8: Reapply for any rework

If you must come back:

• Verify the issue
• Determine cause (typically: contamination missed during initial; reapplied due to ongoing construction nearby)
• Reclean affected areas

Working with general contractors

Post-construction is typically a GC contract; the GC pays you.

Pre-bid conversation

Before quoting:

• What's the spec? (visible cleaning, microscopic cleanliness, etc.)
• When does construction complete?
• When does occupancy?
• What's the timeline window between these dates?
• Who's paying? GC or owner?
• Where's the dispute resolution?

Quote presentation

Provide a written quote with:

• Number of windows
• Pricing structure
• Estimated days for completion
• Materials and methods to be used
• Standard for completion (visual inspection, GC sign-off, etc.)
• Payment terms

During the work

• Coordinate with GC on access
• Track which trades are on site (other trades can re-contaminate)
• Document progress daily

Completion

• GC sign-off on completion
• Photographs of final state
• Final invoice

Coordinating with other trades

A construction site has many trades:

• Drywallers and painters often leave debris that affects windows
• Roofers (over-spray of sealants)
• HVAC installers (filter dust)
• Cleaners often work after window cleaning

Recommend completing window cleaning AFTER all other trades are done. If window cleaning happens too early, re-contamination requires re-cleaning at no additional charge (usually).

Quality criteria

The GC's spec for completed work typically:

• Visible cleanliness under normal lighting
• No visible streaks
• No water spots
• No paint over-spray remnants
• No sticker residue
• Frames and tracks cleaned (often included; sometimes separate)

For premium specifications (hospitals, museums):

• Microscopic cleanliness
• Specific cleaning protocol
• Documentation

Common post-construction problems

Tempered glass scratches

This is the single largest financial risk on a post-construction job, and it can put a small contractor out of business on one elevation of storefront glass.

Tempered glass is heat-treated on a roller hearth. If the furnace rollers carry glass particles, those particles fuse into the bottom surface of the lite. That is fabricating debris. The surface looks normal and cleans normally, but a blade run across it drags the embedded particles and leaves fine parallel scratches. The scratching is caused by a defect in the glass, not by a bad scraping technique, and it will happen with a brand new blade in a careful hand.

Protect yourself before the first blade touches the job:

• Get the scope in writing. If the specification calls for scraping, say in the contract that scraping is required to meet the spec, that some tempered lites carry fabricating debris, and that scratches arising from that debris are a glass defect.
• Test scrape a small area in a lower corner of each glass type on site, then inspect it at a low angle in direct light. If that test scratches, stop and notify the GC in writing before proceeding.
• Try chemical and non-blade methods first on tempered: a soak with detergent and dwell time, a white nylon pad or a bronze wool on wet glass, or a construction-grade cleaner for mortar and concrete splatter.
• Never dry-scrape anything, and never scrape a coated surface or a heat-treated lite unless the test says it is safe.
• Photograph existing scratches, welding spatter pits, and etching during the pre-bid survey, and share those photos with the GC that day.

When a lite does scratch, stop work on that glass type, document it, and raise it immediately. Replacement is the only real fix; polishing distorts the lite optically and is rarely accepted. Carry general liability that covers this and know your carrier's position before you bid post-construction work.

References

• IWCA (International Window Cleaning Association) standards.
• ANSI / IWCA I-14.1.
• AGC (Associated General Contractors) post-construction cleanup specifications.
• Manufacturer literature: glass manufacturers (Cardinal, Guardian, Pilkington) on glass care.
• Manuall internal: Universal Documenting Service for Insurance.