Can impact windows be cleaned like regular windows?

Take the procedure the National Glass Association (NGA) publishes for architectural glass and hold it up against an impact window, one step at a time. The first step is a soak: NGA's paper opens the wash with “clean water and a mild, non-abrasive glass cleaning solution,” put on with a brush, strip washer or other non-abrasive applicator and lightly agitated to loosen the soil. Those are the tools and the motion NGA sets for architectural glass in general.

The second step is the squeegee. NGA has one used immediately after the solution goes on, to remove all of it from the glass, and among its own DO NOT items is leaving water or cleaning residue on the glass or the materials next to it.

The order and the first check come from the same paper. NGA starts exterior cleaning at the top of the building and works down, so solution is not left on glass that is already clean, and it strongly recommends test cleaning a small area of one window and examining it before the rest of the project goes ahead.

What a laminated pane changes sits inside the first step: what is in the solution, and where it is allowed to reach, because the plastic layer that holds the glass together shows at the edge. The full routine, step by step, is laid out under the published method for cleaning exterior glass; the rest of this page is about the edge.

Cardinal Glass Industries defines laminated glass as a safety glass that “consists of two or more layers of glass with one or more interlayers of plastic (usually polyvinyl butyral or PVB) sandwiched between them,” and says its laminated Sea-Storm glass is used in hurricane-resistant windows and doors. PGT writes of its own product line: “Our hurricane windows and doors are made with laminated glass, which is composed of two pieces of glass bonded together by a strong interlayer.” Cardinal calls its Sea-Storm product impact-rated laminated glass.

Those are two makers describing their own products, and they are the reason impact windows are treated here as laminated glass. Whether a particular window in a particular house is laminated is its maker's documentation to say.

The cleaning consequence is NGA's: the plastic interlayer is “generally exposed around the periphery of the window glass,” and cleaning fluids and their vapors must be kept away from that area. The face of the pane is glass. The rim is where the plastic meets the air, and that is the part the chemistry rules are written for. How the edge rule sits beside the rules for coated and tempered panes is set out under impact, Low-E, tinted and tempered glass types.

NGA's rule for laminated glass is broad: on laminated glass, or windows and doors containing it, nothing corrosive is to be used, such as solvents, acids, bases or other chemicals. It then gives examples of materials that may cause harm, and it introduces them with the words “include, but are not limited to.” The first three are bleach (or other solutions containing sodium hypochlorite), acids, especially muriatic or hydrochloric and hydrofluoric, and ammonia. The list continues to solvents and products labeled flammable or corrosive.

Because the list is open, a product that is not on it has not been cleared. NGA sends the next question elsewhere: “Contact the laminated glass supplier or interlayer manufacturers for additional recommendations and cautions.” What goes into a window cleaning solution, and whether it is soap at all, is its own answer under whether window cleaners use soap.

Because bleach and other sodium hypochlorite solutions are on that list, what reaches impact glass as overspray from work on the roof above is a question about the glass as well as the roof. Whether roof cleaning solution may touch impact windows is answered in the window cleaning questions on roof solution and impact glass.

The frame does not close the gap. NGA writes that glazing sealants, gaskets and tapes are not a sufficient barrier against cleaning agents reaching the glass edge, which is argued in full under what the frame does not stop. What the wrong chemistry can do to the seal of a dual-pane unit is a separate question, taken up in whether window cleaning can hurt window seals.

The PGT, CGI and WinDoor care and maintenance instructions carry a do-not list of their own, written for those makers' windows, screens, doors and hardware. It names a power washer or garden hose; metal tools or sharp objects such as razor blades, putty knives and abrasive pads; and petroleum-based products, abrasive or caustic cleaners and solvents, and hydrochloric or phosphoric acid. The guide warns that these improper tools “may void your warranty and/or damage your products.”

The same guide's glass steps begin with a clean-water rinse to lift the dirt and dust that can scratch, ask for light pressure because excessive scrubbing can lead to scratches, and end with a thorough clean-water rinse so the solution leaves no film. It also has each window or door cleaned and rinsed on its own.

That list is an instruction from those makers about their products, not a rule every brand has published, and what a different window's warranty allows is that window's maker to say. Why the hose is on the list is taken up under whether windows can be cleaned with a garden hose, and whether a blade belongs on glass at all under scraping windows with a razor blade.

An impact window can be more than one thing at once. The laminated pane can also be part of a dual-pane unit, or carry a coating, and each of those brings its own rule on top of the edge rule. Whether a coating is present and which face it sits on is covered under whether Low-E windows need special cleaning.

The sun is a second check, with a scope of its own. NGA's direct-sunlight rule is written for tinted and reflective glass, and it is set out under whether tinted windows can be cleaned. The PGT, CGI and WinDoor guide gives its own tip for its products' glass: cooler temperatures, out of direct sun.