The NFRC Consumer Guide to Windows says seal failure can result in condensation from moisture penetrating between the panes, which is the haze a buyer sees. InterNACHI’s Standards of Practice say the inspector shall report as in need of correction any window that was obviously fogged or displayed other evidence of broken seals. The Standards also list determining the integrity of multiple-pane window glazing or thermal window seals among the things the inspector is not required to do. So foggy windows are worth raising with the seller.
Per the guide, seal failure leads to the loss of insulating gas and can degrade low-E coatings. Per the Standards, an obviously fogged window is reported, and seal integrity isn’t something the inspector is required to determine. A buyer who never asks may not know what the report did and did not look at. No repair steps here, and no contractor advice. This is general information, not safety, legal or insurance advice.
What Do Foggy Windows Mean When You’re Buying a House?
The NFRC Consumer Guide to Windows says seal failure leads to the loss of insulating gas and can result in condensation from moisture penetrating between the panes, which can degrade low-E coatings. That’s the mechanism the guide describes. It isn’t a verdict on any particular window in any particular house.
The guide also says the durability of insulating glass units is critical to window energy performance. That’s the link it draws between a seal and how a window performs.
The guide points to field studies as well. It says those studies have shown that insulating glass failure rates differ greatly depending on the quality of seal systems and manufacturers’ quality assurance.
The guide is written for people choosing windows. So it describes how insulating glass works, not a particular house.
Will a Home Inspector Report a Fogged Window?
InterNACHI’s Standards of Practice say the inspector shall report as in need of correction any window that was obviously fogged or displayed other evidence of broken seals. The Standards also say the inspector shall inspect a representative number of doors and windows by opening and closing them.
The Standards’ Exterior section lists a representative number of windows among what the inspector shall inspect. The same section lists determining the integrity of multiple-pane window glazing or thermal window seals among the things the inspector is not required to do. It’s worth knowing both lines before you read a report.
During a home inspection, one of our licensed inspectors performs a visual examination of the structure and all major systems. Windows are among the areas examined. Every finding is documented with photographs, so nothing is left to guesswork. If you’d like to know what the written report will note about the windows, ask us.
The limits of a visual inspection are the subject of our post on what a home inspection doesn’t cover.
What Can’t an Inspection Tell You About Window Seals?
The Standards say an inspection will not identify concealed or latent defects. A visual inspection can report what is visible on the day. So a report about the windows records what was there to be seen while the inspector was in the house.
The Standards have the inspector inspect a representative number of windows. So it’s fair to ask which windows the report covers, and whether any weren’t reached. A report line about the windows records what was seen on those windows, on that day.
A window’s age and history are a different kind of question. The seller may know when the windows were installed, or whether any have been replaced. A report can’t supply that. Ask the seller.
What to Ask the Seller About the Windows
Put the questions in writing, and do it while the contingency clock is still running. It doesn’t need to be long. The maker is worth asking about too, because the guide says failure rates differ greatly depending on the quality of seal systems and manufacturers’ quality assurance.
- How old are the windows?
- Have any of them been replaced, and when?
- Has any window looked hazy between the panes?
- Is there paperwork for the windows?
- Who made them?
A written answer from the seller gives you something specific to bring to the inspection and to your real estate agent. Questions about the agreement of sale are for your real estate agent. Repair and replacement questions are for a qualified window professional.
What If the Report Flags a Fogged Window?
The Standards say inspection reports may include additional comments and recommendations. So a flagged window is a prompt, not a measurement. Ask which window it is. Ask what the inspector saw and wrote down. That’s where the next round of questions starts.
Ask the inspector what was visible and what wasn’t. Ask the seller what they know about that window’s history while your contingency window is still open. Leave cost and repair questions to the right person. Those conversations go to different people.
Who can require a repair after a report is a separate question. Our post on what repairs are required after a home inspection covers it.
Frequently Asked Questions About Window Seals
Can haze between the panes be a sign of a failed seal?
The guide says seal failure can result in condensation from moisture penetrating between the panes. The Standards say the inspector shall report as in need of correction any window that was obviously fogged or displayed other evidence of broken seals. Neither passes judgment on the window you’re looking at, so treat haze as a reason to ask rather than a conclusion to draw.
Does a home inspector check every window?
The Standards have the inspector inspect a representative number of windows, and a representative number of doors and windows by opening and closing them. That’s the wording to hold onto, and it’s why asking which windows the report covers is reasonable. During a home inspection, one of our licensed inspectors performs a visual examination of the structure and all major systems, and windows are among the areas examined.
Does a failed seal change how well a window insulates?
The guide says seal failure leads to the loss of insulating gas. It also says the durability of insulating glass units is critical to window energy performance. Neither statement comes with a figure. If you want to know what the written report will note about a window, that’s a fair question to put to us before the inspection.
Do all insulated glass windows fail at the same rate?
The guide says field studies have shown that insulating glass failure rates differ greatly depending on the quality of seal systems and manufacturers’ quality assurance. It’s also the reason a seller’s written answer about who made the windows is worth having before you make a decision.
Can an inspection tell how old the windows are?
A visual inspection can report what is visible on the day, and the Standards say an inspection will not identify concealed or latent defects. The age and history of the windows are questions for the seller, who may know when they were installed or replaced. That’s the seller’s information to share, and a written report with photographs gives you something specific to bring to the conversation.
Ask About the Windows Before You Close
Inspection Professionals’ written report documents every finding with photographs and is delivered within 24 hours, so you can see the evidence for each finding rather than a summary.
As a general rule, a written report with photographs gives you something specific to bring to the seller about the windows. You’re asking about a documented finding, not a memory from a showing.
A full home inspection is the written report to have in hand while you ask.
If you’re buying in Bucks County, Montgomery County, Philadelphia or Delaware County, contact Inspection Professionals to talk through what a written home inspection documents before you weigh foggy windows in a house you want to buy.
