A rock comes off a truck tire and leaves a star the size of a dime in the windshield. On a car you might leave that star alone for a month and nothing much happens. On a motorhome the same star can be a crack running past the center post by the end of the next trip. Same glass, same rock. What is different is what the glass is mounted in and how much that mounting moves.
Owners ask us why RV glass seems to fail so fast, and the answer is not that RV windshields are made cheaply. It is that a car windshield lives an easier life.
A crack grows from the tip, not the middle
When a rock hits laminated glass it crushes a small cone out of the outer layer. Around the edge of that cone are fine legs, and the end of each leg is a sharp point in the glass. Stress concentrates at a sharp point. Every time the glass is loaded, flexed, heated or cooled, that point moves forward a little. It does not travel in a straight line and it does not travel at a steady rate. It sits still for weeks and then runs eight inches on one cold morning.
So the question is never whether the chip is bad looking. The question is how much load the glass sees and how often it sees it. On an RV the answer to both is more.
The opening the glass sits in actually moves
A car windshield is bonded into a stiff steel unibody. The opening barely changes shape. A motorhome is a house built on top of a chassis, and that chassis twists. Pull into a campground with one front wheel up on a berm and you can watch a door gap change width. Back over a curb cut at an angle and the whole front cap racks slightly.
The windshield is part of that structure. When the opening flexes, the glass flexes with it, and the chip takes the load. A travel trailer front cap window does the same thing every time the tongue loads and unloads over a dip.
This is why two owners with identical chips get different outcomes. One of them parks on level concrete and drives the interstate. The other one is in and out of gravel sites.
The span is longer, so heat does more
An RV windshield is large, and on most Class A coaches it is two pieces with a divider between them. Glass expands when it heats and contracts when it cools. Across a car windshield that movement is small. Across four or five feet of RV glass sitting in Texas sun it is enough to feel at the edges.
Now add the way we use these coaches. The glass bakes all afternoon at 140 degrees on the surface while the dash air conditioning runs cold against the inside. In the winter the defroster goes on full against glass that spent the night near freezing. Each of those is a load cycle at the tip of the chip.
A windshield sunshade is worth more on an RV than most owners think, and not only for the dash.
A lot of RV glass is set in rubber, not bonded
Many RV windshields are held in a rubber gasket under compression rather than bonded in with urethane the way modern automotive glass is. A gasket set piece of glass can move a little in its channel. That is partly by design, because the structure moves. It also means the edge of the glass is supported by rubber that hardens with age.
When that gasket goes hard, the glass stops being cushioned and starts being pinched. Chips near the edge on an older coach run for this reason, and so do cracks that appear with no impact at all.
Where the chip sits matters more than how big it is
When we look at a chip, position tells us more than diameter.
- Within about two inches of the edge. The edge is where the glass is held and where stress is highest. Edge chips are the ones that run, and they are the ones we are least willing to call repairable.
- In the driver’s line of sight. A resin repair leaves some distortion. Filling a chip directly in front of the driver trades a chip you can see around for a blur you cannot.
- Already a crack, not a chip. Once there is a line, injecting resin at the impact point does nothing for the far end of the line.
- Full of dirt or water. A chip that has been open through a rain or two has contamination in it. Resin bonds to clean glass. It does not bond well to a chip that has been sitting open since spring.
When a repair holds and when it does not
A clean chip, small, away from the edge, out of the driver’s view and caught early is a good candidate. We drill or clean the impact point, draw the air out, push resin in under pressure and cure it. Done properly it restores most of the strength and stops the legs from running.
What it does not do is make the chip invisible. Anyone who promises that is selling something. You will still see a faint mark where the impact was, and that is a fair trade for keeping the glass.
We also tell people honestly when we do not think a repair will hold. If the inner layer of the laminate is damaged, or the chip has several long legs, or it sits at the edge, filling it buys very little. It is better to know that before paying for it than after.
Replacing RV glass is a sealing job as much as a glass job
Here is where RV glass and automotive glass separate completely. On a car, a new windshield that leaks means a wet carpet. On a motorhome, a windshield that leaks sends water into the front cap, down behind the interior panels and into the floor. We have opened up front walls where the only visible symptom was a soft spot under the passenger seat and a smell, and the source turned out to be a glass job done years earlier with the gasket reused.
So when we set glass we look at the channel, the gasket condition, the condition of the structure behind it, and whether anything has already been getting wet. If there is damage in the opening, filling it with a new windshield only hides it. That work is handled alongside our RV body repair side when the opening itself needs attention.
Glass work on these coaches happens at the shop on Rhodes Rd, where the coach can sit level, out of the wind, while the sealant cures. The details of what we set and on what kinds of coaches are on our RV windshield replacement page.
Glass and your insurance
A lot of RV glass goes through insurance rather than out of pocket, because comprehensive coverage commonly includes glass damage from road debris. What it costs you depends on your deductible and on how your policy is written, so read yours or call your agent before you assume either way. Texas does not have the zero deductible glass rule that some other states do, so do not count on that.
What we can do is document it properly. Photographs of the impact, the measurements, the glass part itself and the condition of the opening, written up the way an adjuster expects to receive it. If the chip came from the same storm or the same incident as other damage, it belongs on the same claim as the rest of it rather than being handled separately. That is the point of our RV insurance claim estimate, and it is worth starting there before the crack decides the question for you.
What to do with a fresh chip
Three things, in order. Put a piece of clear tape over it so it stays clean and dry. Keep the defroster and the dash air off that part of the glass until it is looked at. Then get it seen while it is still a chip, because the difference between a repair and a new windshield is usually a few weeks of waiting.
We work on motorhomes, travel trailers and fifth wheels out of our shop in Spring, and owners from Spring, Conroe, The Woodlands and the rest of the north Houston area bring their coaches to us. If you have a chip or a crack in your RV glass, call the shop at 346-708-4612 and tell us where on the glass it sits, and we will tell you honestly whether it is worth repairing.