

Homeowners Guide: How to inspect glass after a window replacement.
by the American Architectural Manufactures Association
The following guide is not created by Karoly Windows & Doors. It was created by AAMA and distributed to manufactures for industry standard guidelines on glass defects. Karoly Windows & Doors should not be held liable for any of the content listed below. To be directed to the AAMA website please click here.In order to simplify the glass inspection process for homeowners who have just had their home’s windows replaced, the AAMA put together this guideline. This guide doesn’t guarantee the manufacturer will approve the warranty claim. That is the decision of the manufacturer’s warranty technician. Rather, this guideline will help the homeowner flag whether an issues merits the consideration for warranty replacement. Click here for more information.
The following guides were developed as industry standard. These standards are not always specific to different types of glass. Being up to the manufacturers discretion as what warrants a claim, this is a guide to help you determine what you can claim. Impact glass unit issues are held to these standards for LowE, Argon gas, with a laminated interlayer impact glass units. How is a homeowner to know whether an issue or blemish is a legitimate concern on their replacement windows and doors? To download and print the chart below click here.

Homeowner’s Glass Inspection Directions
- Thoroughly clean the glass on both sides with a glass cleaner.
- Stand 10 feet away, directly in front of the glass (90 degrees to the surface).
- The glass should be illuminated with daylight, but not direct sun.
- If an issue or blemish is readily apparent, measure the size of the blemish.
Contact the manufacturer if the blemish is noticeable and is outside of the following limits:
Blemishes: | Maximum Size (if readily seen at 10' | Separation (between blemishes) |
Point blemishes (dirt, debris, residue, pinhole, spot, finger print, etc.) | 1/16" | 24" min |
Linear blemishes (scratches, rubs, marks, etc.) | 3" | 24" min |
Glass chip | 1/4" x 1/2" | 1 per pane |
Other Issues: | Definition | Comments |
Bow | Deviation in flatness spanning the entire pane of glass. Commonly seen in tempered glass and IGUs | Not measurable on site or in an IGU. Positive and deflection is a natural occurrence with seasonal and barometric |
Distortion | Localized deviation in flatness that can look like ripples across the glass, or pockets of indentations | Allowed and very common in tempered glass. Not measurable on site or in an IGU |
Strain pattern | An optical effect that results from the tempering process appearing as a pattern of dark spots on the glass. The intensity of the issue increases when viewed at steep angles to the glass and with polarized sunglasses | Allowed. This optical issue is characteristic of tempered glass and cannot be completely controlled. It will vary from pane to pane. |
Fringes | An optical effect that appears as a faint, random, pattern resembling an oil stain. | Allowed. This is the result of having exactly matched thickness of glass panes in an IGU (less than 0.0001" difference in thickness). |
Newton rings | This is an optical issue that appears as concentric rings of rainbow colors near the center of an IGU that has its panes touching each other. | There is no industry standard covering this issue. Contact the manufacturer. |
Color uniformity | Readily apparent glass color variation from window to window, or within a window. It can be the result of the glass tint or glass coating. | Allowed within reason. Can be measured with special instrumentation if needed. Consult with the manufacturer. |
Suction cup marks and label residue | Telltale impressions on the glass where a suction cup or label was applied. | Allowed if on the outdoor or indoor surfaces of an IGU, and seen only when the glass is wet with rain or condensation. Not allowed if the marks are inside the IGU and noticeable at 10 feet or more. |
Fogging | A moisture or chemical deposit between the panes of an IGU. | Not allowed. Indicates seals have failed or outgassing of materials has occurred. |
Sightline infringement | An extension into the daylight opening of an IGU by the sealant, spacer, or area of coating deletion. | 1/8" maximum |
Still unsure if the issue is a warranty concern?
Stand 10 feet away, take a photo and email it to our company. office@karolywindows.com
Our project consultants will help you determine if this is an issue for warranty through the manufacturer. They can provide the warranty claims phone number or they can help you initially report the warranty claim. It is then up to the manufacturer to perform any warranty actions on the glass unit.
Our door is always open.
Our project consultants are standing by to take your calls. We also have a showroom in Clearwater you can visit during normal business hours.