What a Construction Window Cleaner Sees

Reprinted from the October 1996 issue of FENESTRATION

by Dan Fields

A primer on glass scratching and other problems that arise after windows and doors are installed on the jobsite.

There is nothing simple about construction window cleaning. I know. I have been in the business for over 30 years, having learned the trade from my father, who learned from his. I have seen many changes in the industry, good and bad. I have seen innovations come and go and I have survived, profitably.

This article will discuss the responsibilities of the construction window cleaner, other subcontractors, and the general contractor and the major causes of widespread problems that occur involving windows and doors. In particular, it is the purpose of this article to enlighten those in the window industry and other responsible parties involved in residential construction on how to identify the three major causes of scratched glass and some proposed solutions to this widespread problem.

It is widely accepted that the window cleaner is solely responsible for the condition of the windows after they have been cleaned. Current reasoning is that "if there are scratches, then they must have been caused by, and only by, the window cleaner." However, the reality is that precautions can and should be taken by all trades before, during, and after the window cleaning is done to ensure a scratch-free window.

It is the rule rather than the exception that the construction window cleaner will encounter excessive plaster, paint, and texture overspray; splashed concrete, mortar and mud; and smeared silicone and grout on the windows. Although a moderate amount of these items can be expected, the current practice of an accelerated building schedule, coupled with the declining level of competence and the capability of other trades, has resulted in an irresponsible attitude toward protecting the glass and window and door frames.

It then becomes the responsibility of the construction window cleaner to remove all such debris from the windows without damaging the frames, glass, or sealant. The window cleaner should be knowledgeable enough to make a determination prior to commencement of work that this cleaning can be done safely, without risk or damage to the windows and subsequent liability for such damage. Unfortunately, many window cleaners are not properly trained to clean windows safely, to determine the cause of existing scratches, or to even notice that there are potential hazards on the glass.

There are three prevailing causes of scratches on glass. First there is the damage caused by subcontractors during the construction of the house. Here are a few examples of jobsite practices that can do irreparable harm:

    • Workers putting ladders and equipment against windows
    • Lathers dragging wire lath across glass
    • Plasterers wiping plaster off glass
    • Painters dry razor blading paint off glass and sanding perimeter wood doors
    • Welders grinding steel rails in area of glass
    • Masons smearing mortar on glass
    • Tile contractors wiping tile grout off of glass
    • Interior texture contractors scraping excess texture off a dry window and/or letting sanding pad ride on glass when sanding texture, prior to painting
    • It cannot be overstated that the competent window cleaner must know how to identify these factors prior to cleaning the window.

A second source of scratches (and the most common) is the technique that the window cleaner chooses to clean the windows and doors. The tools and methods used and the preparation taken prior to cleaning the window are all significant factors.

For example, the glass must be kept wet during the cleaning process. Razor blades or broad knives should never be moved backwards on glass. This will trap debris under the blade and cause scratches. Excessive plaster, cement, and grout must be chemically loosened from the window (i.e., dissolved off the surface) before any window cleaning takes place.

The third cause of scratched glass, rare in the past but becoming more common, is limited to scratches found on tempered glass. Some tempered glass has a blemished surface, usually but not always found on the side of the glass with the identifying safety engraving. This blemished surface consists of small pimples on the glass not visual to the casual eye, but which cause a "tinkling" sound when scraped off the surface. These pimples, which can be created during the tempering process, are scraped off during normal construction window cleaning and the dragged across the surface of the glass, causing numerous scratches.

This condition has been confirmed by several experts and consultants in the glass and tempering industry. Although there is no universal agreement on the technical terms or the causes of this condition, the resultant scratched glass is undeniable. The terms being used to describe the surface condition range from heat prickling, orange peel, roll pick, heat scorch, pitting, seeds, kinks, cheeks, pimples, bubbles, and blisters to just plain garbage that was not washed off prior to the glass entering the tempering furnace.

The causes being blamed for the condition include dirty furnace rollers, dirty filters, dirty furnace conditions, location of furnace in factory (proximity to other equipment), overheating of the glass, and not cleaning glass prior to entering the tempering furnace. Although this type of blemished surface found on tempered glass is growing more commonplace in residential construction, it should be unacceptable to window and door manufacturers, builders, and reputable developers.

Preventing problems

Once the major causes of scratched glass are recognized, all parties must work together to prevent the problem from occurring. Care must be taken by the general contractor as early as the bidding process to ensure that hired subcontractors are careful and qualified. In the short term, an acceptance of a subcontractor's appealing low bid may lead to expensive problems down the road.

Subcontractors should be required to protect all the windows in the area where they are working to prevent any damage that may be caused as a result of their work. In the large scheme of things, tape and plastic can do much to protect the windows and the exposure of the subcontractor.

Any window cleaner hired for a project must have the knowledge required to clean windows in a construction environment without causing damage, and should also know the limits of his ability. Once again, a low bid may indicate a lack of experience necessary for safe and effective cleaning. Excessive amounts of debris on glass, whether texture, paint, plaster, concrete, or anything else, should be brought to the attention of the job superintendent prior to cleaning.

Any person cleaning heavily soiled windows without the proper tools or techniques should be stopped by the project superintendent. This pertains not only to the contracted window cleaner, but also to any subcontractor trying to clean overspray or other debris from the window.

With respect to the scratches caused by cleaning blemished surfaces on tempered glass, it is the sole responsibility of the glass tempering company and/or the window and door manufacturer to ensure that all windows and doors incorporating tempered glass have a blemish-free surface. This will enable the construction cleaner to clean minor debris from the glass without scratching it.

General contractors should only purchase windows and doors from reputable manufacturers with proven track records. When windows are delivered to the jobsite, especially during the model stage or if there is a new window supplier, the superintendent should wet a section of the stamped side of a tempered glass door or window, then take a razor blade and run it over the wet surface of the glass on the stamped side. If he hears a "tinkling" sound, this glass is flawed and the unit should not be accepted from the manufacturer. It is much less costly to ensure, prior to installation, that all windows and doors are free of this blemished surface.

Ultimately, it is the responsibility of the general contractor to see that all subcontractors and suppliers perform and supply a quality product. Regardless of the position taken by any subcontractor or supplier on this issue, the homebuyer has paid for and deserves a scratch-free window or door. It is to this end that we should all strive.

Dan Fields is the owner of Fields Window Cleaning, a construction cleaning company based in Livermore, CA. With more than 30 years experience, he also acts as a consultant to determine the causes of scratched glass on new residential construction jobsites.

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