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Repairing a window with fogged glass

In last week's blog post, I showed some examples of insulated glass units with failed seals and explained the difference between a failed seal and fogged glass. In short, a failed seal eventually leads to fogged glass, but will not be immediately noticeable. As I mentioned last week, I had a bunch of windows with failed seals at my home, so I hired A Pane in the Glass Construction to come repair my windows. I found them on Angie's List. While one option for repair would be to replace each window that had failed glass with a new one, it would also be the most expensive option.

A less expensive option would be to have just the window sashes replaced. When window seals are covered under a manufacturers warranty, it typically just takes a phone call to the manufacturer with some serial numbers from the window, and they'll make up replacement sashes. Replacing a sash on a newer double-hung window is usually quite simple, and can be done without any tools. Unfortunately, my windows had no such warranty.  I opted to have just the insulated glass units replaced, frankly because I don't think there would be any big benefit from having a bunch of the windows entirely replaced, and the cost to replace just the insulated glass was far less.

The guys who replaced my glass units said it would be fine to share photos of the entire process for anyone who is curious, so here goes. To start, I had someone stop by my house to take measurements of all the insulated glass units that were fogged. He made note of which windows were fogged, if the glass had grids or not, and partially disassembled the windows to make sure he was getting exact measurements of each insulated glass unit.

Measuring glass

They used these measurements to order new, custom insulated glass units from a local manufacturer. The glass was ready in about two weeks.

To replace the glass, the first step was to remove the vinyl trim pieces around the perimeter of the glass.

Vinyl channel removed

The next step was to use a pizza-cutter-looking tool called an E.Z.D. Glazer to cut through the adhesive at the exterior, which held the glass to the vinyl sash.

Pizza Cutter thingy

This particular unit was especially difficult to take apart, so they had to use a spatula-looking-device that I didn't get the name of, along with window cleaner at the exterior to really help loosen the glass and get in the corners.

Working on window from exterior

Once the glass was loose enough, they used a glass suction cup to pull the glass unit out of the frame.

Glass suction cup pulling

Glass unit coming out

This one came out in one piece, but they weren't so lucky with several other windows.

Broken glass

This particular unit had a very bad seal; the individual pieces of glass weren't even attached to the spacer in some places. Check it out.

Glass separated from spacer

Once the glass unit was removed, replacement was about what you might expect. They cleaned the vinyl frame, applied a bead of silicone caulk to the perimeter of the frame, and then placed the new glass into the opening.

Sililone applied to sash

Once the new glass unit was put into place, the vinyl trim pieces were replaced and the glass was thoroughly cleaned. That's about it. I can see clearly through all of my windows now, and I'm glad I had this work done. Oh, and the guys who did the work were great.

The cost to replace the glass was about $150 per unit, and as I said earlier, I had a lot of units that needed replacement. If I had only had one or two glass units to replace, the cost for each unit would have probably been about twice as much, because the company doing the work would need to make the project worth their time.

Author: Reuben SaltzmanStructure Tech Home Inspections


Failed window seals: A common cause of foggy glass

One of the most common window and door issues that comes up during a home inspection is fogged glass, more commonly known as a broken seal. For a nice description of exactly what causes a broken seal, head on over to the Family Handyman.

Interestingly enough, identifying failed seals on insulated glass is something that is specifically excluded by home inspection standards of practice. Just in case you don't know what I'm talking about, check out the photo below. Two of these four window panes have badly fogged glass.

Fogged windows

When an insulated glass seal fails, there are three things you might see when looking through the glass: nothing different at all, condensation or dirty/hazy glass. When a seal initially fails, nothing dramatic happens, and there is no visible evidence of a failed seal. A desiccant around the perimeter of the glass unit will help to prevent moisture in the air from filling the space between the two pieces of glass. This will keep the glass looking just fine, at least for a while. This is why home inspection standards of practice exclude the identification of failed seals. There is oftentimes just no way to know.

Given enough time, moist air begins to fill the space between the two formerly-sealed pieces of glass. When temperatures remain fairly constant, you won't notice this moisture in the glass. Only after there has been a fairly rapid change in temperature, either indoors or outdoors, will you see any evidence of a failed seal. This starts out as condensation between the two panes of glass. The photo below shows a nice example of a window on my own home that just this fall started showing evidence of a failed seal (lucky me). This window looks perfectly fine most of the time, but just a few weeks ago I noticed a nice little band of condensate between the pieces of glass.

Fogged glass, early failure

This condensate was only there for a few hours, and I haven't seen it show up again since, but I'm sure it will keep coming back more and more frequently, and the amount of condensate, or fog, will only grow. After this has happened enough times, a mineral deposit gets left on the glass, making it look dirty all the time, even when there is no condensate present. The photo below shows an example of another window in my house with some faint, annoying deposits. I added a few arrows to the image to highlight this area.

Fogged glass with mineral deposits

When insect screens are present or when the glass is dirty, fogged glass like this may not be visible. That's another reason home inspection standards of practice don't require identification of failed seals. When I inspect a home with numerous panes of fogged glass, I often tell my clients that while I may identify many locations of fogged glass, I'm probably not catching every one, especially if the windows aren't perfectly clean.

Once a window or door has had a failed seal for several years, the glass gets dirty enough to the point where it's completely obvious all the time, and it becomes quite bothersome to look through the fogged glass. I had a few panes of fogged glass at my house when I moved in, but that number has grown from a "few" to a "whole bunch" in the past several years. My wife and I couldn't take it any more, so we decided to have the windows repaired.

I'll share the repair process in next week's blog post.

Author: Reuben SaltzmanStructure Tech Home Inspections