Causes of Sunroof Explosions


car-exploding-sunroof

Broken sunroofs can be common, but the reasons for them vary. Have you ever heard of an exploding sunroof, or been in a car when one did?

Though still rare, the number of exploding sunroofs reported has increased and with them has come lawsuits against car manufacturers.

Allegedly exploding sunroofs have been seen in all kinds of vehicles—Volvos, Fords, Lincolns and Nissans among others. All four of these manufacturers were named defendants in cases that allege these panoramic sunroofs exploded spontaneously. Most of these occurred while the vehicles were traveling at highway speeds, but no one is certain exactly what caused the explosions.

Types of Sunroof Glass

Most of the lawsuits describe the various types of glass used in the sunroofs but do not suggest a particular cause. Sunroofs usually are made of either tempered or laminated glass, which both have pros and cons. Tempered glass is made by heating and cooling a piece of standard glass in a tempering furnace. The glass, which must be pre-cut and edged before being put into the tempering furnace, is heated to approximately 1200°F and then cooled rapidly. Laminated glass is basically a glass sandwich. It is made of two or more plies of glass with a vinyl interlayer between (sandwiched, if you will, as in a car’s windshield).

A recent lawsuit against Ford claimed that while some car makers utilize laminated glass, Ford has chosen to use tempered glass in its sunroofs. They also suggest that Ford uses “thinner glass … [which increases] the probability of catastrophic failure.”

Russ Corsi, an independent automotive glass consultant, says it’s up to the manufacturer to decide what’s important to them. He says that it just depends on what the manufacturer wants the glass to do and how they want it to appear.

What Professional Auto Glass Installers Say

Many sunroof installers say they don’t believe that the type of glass is an indicator of cause. Instead, they suggest the cause is likely a matter of physics.

Neal Ailstock, an installer with Seatco in Springfield, Va., says he sees six or seven blown-out sunroofs a year in his small shop. He thinks that the way the glass is held in place has a lot to do with the spontaneous explosions.

Ailstock says the glass usually is held in place by “two beads of high-strength urethane. That glass can’t move. It has to flex.

“When a car goes too fast around a corner, the body starts to flex,” Ailstock explains. “But the glass is glued in and can’t move, so something’s got to give.”

That often means the sunroof, he says.

Jesse Garcia, who works at Texas Auto Tops of Austin, says the seal of the glass is key – but notes that he hasn’t seen a lot of these “spontaneous” exploding sunroofs.

His boss, shop owner Garal Kelley, agrees that instances of spontaneously exploding sunroofs are “rare.”

“I’ve heard of sunroofs blowing off cars,” he says, “and that’s usually because the seal between the glass and the metal has started to de-laminate.”

Kelley says some of the adhesives used on sunroofs can fail, causing the sunroof to leave the vehicle.

“When they break, either somebody has dropped something on the glass or something has gotten stuck in the sunroof,” he says.

Other Reasons Sunroofs Shatter

Kelley says there are other reasons sunroofs might shatter, such as a small rocks or pieces of debris that can chip the glass. If the glass is tempered, sudden changes in temperature can cause the glass to expand and contract and cause the chip or crack to grow or shatter completely.

Ian Hanshew, the owner of Champion Glass in Woodbridge, Va., echoes Kelley. He says sometimes you can tell what debris hit the glass, and other times he finds that a mechanical part of the sunroof, such as a clip designed to hold it in, contributes to the breaks.

Hanshew’s shop specializes in new cars models and puts in approximately 50 sunroofs a year. His employees often keep notes about the sunroof breakage brought to them for replacement, but they don’t retain records about what type of glass was used in the originals.

David Arriaga, installer at South Gate Sunroofs in Huntington Park, Calif., says he has not seen any “exploding sunroofs” like those named in the reports. He says it’s “really, really rare” for the glass to shatter spontaneously.

Cliff Monroe, a glass expert who has been in the industry since 1970 and is now CEO of GlasFab Architectural Consulting, says that there’s not a definite way to pinpoint the causes of the explosions. He likens it to the lengthy process of “solving a murder case via a forensic analysis of the particles.”

What’s in the Glass?

The type of glass could play a role, Monroe said, but so could whatever is in the glass or on its surface. Corsi agreed that identifying the cause specifically would require a detailed analysis, and there could be a lot more to it than the type or thickness of the glass. It could have to do with the amount of stress put on the glass when it’s installed. It could be something as simple as a car wash, he says, and the abrasive brushes used in them.

The curvature of the glass used in sunroofs could even play a role, according to Corsi, especially in panoramic sunroofs. “The more curve in the glass, the more stress on it,” Corsi says.

What Now?

Have you been impacted by the spontaneous sunroof breakage? Comment below to let us know about your experience. Do you have a broken sunroof now? If you have a broken sunroof, whether it broke spontaneously or not, you can use the Glass.com affiliate  locator service to find a shop today to discuss details about what is involved in replacing the sunroof.

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38 responses to “Causes of Sunroof Explosions”

  1. Ummmm…..What type of glass does Jeep and Dodge use? My Mother has a 2008 Jeep Grand Cherokee. It has a sunroof.

  2. 2017 Volvo S90 8,000 miles. Sunroof spontaneously exploded. Driving about 50 mph road was clear with no car in front or approaching. This was not an impact caused incident. Noise was very loud. At first thought bullet had hit car. Was not heat related. In 70s. Glass was tempered. Dealer denied was warranty issue. Sunshade was closed so glass did not enter cabin. Two weeks in shop. Roof and rear deck paint damaged by glass shards. Called Volvo customer service who stated was not known issue. Expect tempered glass was used to reduce weight. Many vendors have this issue. Because it is not isolated to a particular auto manufacturer this may be an issue with a common glass supplier.

    • Howard, thank you for sharing your story with us! I’m sorry to hear that you’re another victim of this phenomenon. Hopefully spreading the word about these issues will bring about resolution.

  3. I was driving down the road, 70mph, temp outside 36 F. Heard a loud noise like a shot above my head. The sunroof had exploded. Subaru dealer says it must have been a rock. Though no car was close enough on the sides or in front of me. I was not traveling under a overpass. I was told that the glass is made to explode and shatter outward during impact. I have a 2016 Subaru Outback

    • My sunroof exploded yesterday. 2013 Subaru Outback. Driving 55 mph on a two lane highway. It happened as a truck and a car passed me going the other directions. Same sound, extremely loud shotgun sound. The sunroof is shattered and the outside of the sunroof bowed out. The glass didn’t come down but there is now a hole after driving it home. 100$ deductible with insurance. Could have been a lot worse.

      • Mine exploded on me yesterday as I was driving on the motorway at 60mph..
        it sounded like a gunshot going off..
        I was the only car so nothing waS near to me…
        The sunshade was open so the glass came in the car..
        There was a huge hole and the rest of the glass was bowed out like yours also…
        I have a Mercedes.
        I’m glad my 2 little ones were t in the car !
        It was not a nice experience and I’m hoping to get it sorted today..
        Did u find out the cause of it?

  4. 2017 Volvo S 90… Traveling 495 north in the state of Massachusetts… 30° outside 72° inside the car… Sunroof exploded. Sounded like a shotgun… As I pulled over to the side of the road… Vehicle behind me (subjected to the flying glass) pulled over with me and offered to be a “witness“. I returned the car to the dealership – two hours later… At first they asked for my insurance company‘s name and policy number… Three hours later they called to say that Volvo would be covering the sunroof under warranty… $800 for the glass and seven hours labor to install it and fix the minor damage. Bravo Volvo. Thanks for making an unpleasant morning entirely bearable. 🙂

  5. I was driving yesterday, March 18th in Colorado, I just drove down Hoosier Pass going south on Highway 9 outside of Breckenridge when my back panel of the panoramic sunroof exploded. It sounded just like the others expressed, like a gunshot hit my car. I was driving about 55 miles per hour, with traffic in front and behind me, but not close, say 20 yards, and no car or truck passed me. When I pulled over, I was shocked to see a large hole in my sunroof with shards of glass all over the backseat. The whole sunroof was shattered. It is now at the dealership, and I am hopeful Jeep will find it a mystery as well. The hole was so large, a rock would have been in my back seat, but I found nothing but glass. Freaky!

  6. My 2014 Jeep Grand Cherokee sun roof just exploded on a sunny day while driving at 65 mph down the highway. No reason for the explosion. Jeep inspected the vehicle and could not find a reason. And of course I’m a couple of months out of warranty so Jeep refused to pay for the repair, even though this is a safety issue.

  7. 2016 Mercedes GL 450 sunroof shattered while parked in driveway overnight. Nothing hit it or anything. The middle of the sunroof was sticking up at first like a punch up from the inside, then fell inward when the door was opened. It was the first hot day we’ve had here in a while and temps dropped overnight. Not sure if that had something to do with it.

  8. My Nissan maxima 2011 panoramic roof exploded while I was on my way to work, remain glass is directed upward like it is blown up from pressure in cabin.

  9. 2011 Acura MDX with almost 100K, in great shape otherwise…on highway in Tx cruising at about 65 mph, temp was 70s and sunny outside…no overpasses or flying items or even debris in rearview after random, unexpected, and totally isolated BOOM like a boulder had been dropped from above…glass exploded outward with no surrounding damage around sunroof…this is important b/c not road debris and engineering defect (whether glass itself or glue used to seal)…dealership and auto client relations’ departments most likely will not be helpful…definitely call the National Highway Traffic Safety Admin and report for sure…LOADS and loads of complaints…2 sunroof manufacturers that I know have recalls are Webasto and Visibility…best of luck!

  10. My sunroof exploded while driving on the expressway. Shattered but still up on roof. Can’t find replacement ..2005 Nissan Altima 2.5 S. Must have been put in after the car was purchased. I bought it used in 2007. Just sucks, cant find the right glass and size. Glass says carlite, shade says Solaire sunroofs…a bit confused….may have to turn it in and get another car. It runs great, I love my Nissan Altima

  11. My wife, myself and cat were on the way for our Summer get-away for 4 months in our 2015 GL450 Mercedes when we heard something like a gunshot and the sun-roof exploded into thousands of small glass fragments. Luckily the fabric cover was closes or we would have small glass blasting into our skin , face, etc. Could not believe is and or if raining, we would be covered in water . Turned around and after 4 hours back at the Mercedes dealer. We are sure nothing hit the glass- Mercedes is taking care of the repair, but I do not trust the glass unless something had changed in the manufacturing -No one at the dealership seems to know–What do we do?

    • Hi Frank,

      Thank you for sharing your experience! These are rare incidents and usually (but not always) are a once-in-a-lifetime experience. The new glass is unlikely to have the same issue.

  12. Driving home on a highway, no other vehicles nearby, no overpass, not even any tall buildings. Heard huge explosion, freely an impact, no idea what it was. Calmed down a bit and thought to check the sunroof, the shade was closed. Yep. Glass shattered. This car has less than 10000 miles on it, it’s less than two years old.

  13. 2017 Mazda 6 GT, near new just driven it for 2 months, sunshade was open, just joined a freeway and accelerated to 98Km/h, heard a loud bang over my head only to see a large hole on the sunroof and glass shattered all over the interior of my car. No evidence of any object from outside the car, still unclear as i had just passed a foot bridge, i have a dashcam footage and nothing suggests an impact from outside.

  14. Today: 2015 Subaru Outback. 64,000 Miles. Driving 55mph; sunroof exploded. Temperature in 70’s. Fortunately, no glass inside vehicle; shade was closed.

  15. 2016 Jeep Cherokee Limited 35,000 kms. Rear sun roof panel exploded while driving in good weather at 100kms\hr in light traffic. No warning just like a rifle shot and then wind noise, pretty scary. My Jeep dealership are closely inspecting it tomorrow but their initial response did not sound as if it will be covered under warranty. Typical dealership response “ we’ve never heard of roofs exploding, don’t believe everything you read on the internet, must have been a rock”

  16. Infiniti Q40 sunroof shattered upwards when the drivers door was closed, early morning, low 70’s, in shaded area. Fortunately the shade was closed. I took some pictures then taped it over with aluminum speed tape around the opening (it wouldn’t hurt the paint) and duct tape over the shattered glass. Finally covered the duct tape with speed tape for a waterproof / drive-able temporary fix. The sticky duct tape kept the shattered glass from falling apart while the speed tape sealed and secured the whole thing. Keeping the shade closed, I was able to drive it for 2 days until I could get into the Infiniti dealer where it was replaced under warranty.

  17. 2018 Subaru WRX sunroof exploded earlier today. Sounded like a cannonball had been dropped on top of the car, so we pulled the shade back and saw the entire glass had shattered. When we stopped to look at what had caused the damage, all we could see was that the remaining glass was bowed outwards. We were on the freeway so a HUGE chip could have caused the damage, but it’s also 98 degrees out.

  18. I have a newer 2018 Volvo XC 90. One day I had a spontaneous crack in my sunroof. I believe it could of happened when I shut my door…don’t know…95 degrees in the Florida heat. Osteen Volvo Dealership here in Jacksonville FL said …call your Insurance Company. Nothing hit the roof

  19. My 2018 Jeep Cherokee altitude back panel of sunroof just exploded today as I was getting onto the freeway not by any other cars. Initial response by dealership is hmmm ever ever heard of that ever. I purchased the car in January and it has 14,000miles on it. They are investigating and will get back to me. I have pictures of the hole in the sun roof bowed out and upward. It is obvious it blew out.

  20. I was just researching and came upon this. My 2014 Volvo s60’s sunroof “exploded” on the interstate going appr. 80 mph. Scared me to death!!! Glass went everywhere. Same scenario as the others, no cars around, overpass, etc. I thought I was crazy!

  21. My 2018 Mazda 3 sunroof exploded overnight while it was sitting in my garage. Same as other stories, glass pushed outward. I took it to the Mazda dealership and the service manager placed a call to Mazda but had not heard back as of the end of the day. It is only 7 months old with 5500 miles. Low temp was 29F, but there was not a huge temperature shift between last night and this morning. My garage is not heated. I’m hoping Mazda will make this right.

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