Saturday, December 3, 2022


Know your RV’s height. What can happen if you don’t!


By Russ and Tiña De Maris
A lot of folks new to the RVing lifestyle are a bit daunted by the size of their rig. They figure all that length can get them into trouble — and it’s true, it takes attention to stay out of trouble. But one of the easier things to forget about with an RV is not so much how l-o-n-g you are but, really, how t-a-l-l you are, i.e., the RV’s height.

More than one new RVer has returned home from the “maiden voyage” only to report some mishap which has damaged their roof. What’s to be done? Well, 28 grams of prevention is surely worth the old pound of cure.

First, always KNOW your RV height. That information may be provided by your rig manufacturer, but don’t go counting on it. You’ll probably need to do the measuring yourself.

How to measure your RV’s height

First, from the side of your rig, eyeball to see what the highest point of the rig is. It’s often the air conditioning unit, but some rigs have a higher roof point — often fifth wheel trailers. In any event, figure the high spot, then ascend to the rig top (carefully!) with a tape measure. If an accessory is the high spot, measure from the edge of the roof nearest the high spot, down to the ground. Then measure the distance from the top of the high accessory to the roof level and add the figures together.

Some have suggested using a laser pointer or laser level, parking it at a known height, and shooting the beam over the top of the rig. Then using a yardstick, measure how much lower (or higher) the rig is in comparison to the laser beam. Maybe the easiest system is this: If the highest point on your roof is, say, the A.C. unit, get a long, flat board (1×4 for example), stick it on top of the A.C. unit, let it hang over the side, and measure up to the bottom of the board from ground level to get the RV height. Whatever works.

What to do when you know the RV’s height

When the RV height is known, write it down on a tag, index card, post-it note, whatever have you, and put it in clear sight of the driver’s seat. That will help you when you’re dealing with “marked height” objects like bridges and gas station canopies. Keeping your eye open while driving is essential, of course, unlike the driver of the commercial bus who tried to stuff his 13′ high rig through a 9′ high bridge opening. Driver excuse: “The GPS was set for bus, and it didn’t say anything about this bridge!”

It gets dicier when you’re dealing with unmarked objects. Low-slung tree branches in RV parks and campgrounds cause plenty of trouble. If in doubt, STOP, get out, and eyeball. Or even better, have your navigator hop out and guide you through the problem. Don’t be afraid to get yourself out of trouble (read this: learn how to back your rig up). When traveling through Upstate New York, we had plenty of occasions where we had to back the fifth-wheel away from low bridges — usually kept hidden around a corner with no prior warning.

How to repair minor roof damage

Now, for that pound of cure: If worse comes to worst, a lot of roof damage can be mended on the road. Unless you’re like that bus driver, what you’re most likely to do (even if you’re careful) is to run under a branch and put a tear in your rubber roof membrane. We always keep a roll of EternaBond brand tape in our repair kit. Sold in various widths, 4″ is probably a good one, but we’re a bit cheap and use the 2″ stuff.

Anyhow, should you tear the roof, clean the roof with approved cleaner. This means, NOTHING that contains petroleum distillates or citrus cleaners. These “cleaners” will swell the rubber, cause damage, and likely void your warranty. Make sure the area is clean and dry.

After cleaning, cut a chunk of repair tape around 1/2″ larger than the damage, peel back the liner, and lay out the repair tape on the roof. Now apply pressure to the tape to get it to “tie” into the roof. A steel roller is great for this, but even the pressure of your hand doing a “Dutch rub” will help make the bond secure. Once the tape is stuck down in place, in most cases you shouldn’t have to worry about it again. Nevertheless, a twice-a-year roof check is always a good idea!


Watch a video related to this article on the RV Travel Channel on YouTube.

The many useful RV applications of Google Earth – Part 2: Height clearances


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1 year ago

You could use Geometry to find the over all height. You would have to know where on the roof the highest point is. (i.e. – Centered or to one side of the roof.) Measure out from the side of your rig and add the length to the highest point to your base line. Set up a pole of known height with a basic protractor with string and weight on it. Find the angle to the highest point and do the math to find the height of the vertical leg. (Note: Don’t forget to add the height of your pole to the vertical leg. This should give you the over all height. BTW, before anyone asks, No I am not a mathematician of any sorts.

Tom Herbert
1 year ago

Most CAT scales have an overhead bar. After weighing, move the rig so the highest point is under the bar (for my 5er, it’s the front A/C) and measure from the highest point to the bar. Also measure from the bar to the ground as the height marked on the bar is usually not accurate. A subtraction gives your rig height. A weigh and a height check all in one stop!

1 year ago
Reply to  Tom Herbert

Thanks! I didn’t know that.

Richard DeAgazio
1 year ago

Don’t forget to inflate your air bags before you measure!!!!

Mike D.
1 year ago

Being a semi driver for 35 years , keep your eyes moving. Look far ahead. Phone and cable lines are commonly hung lower than the standard 15’. Especially in older residential neighborhoods. The connection between utility poles and houses angle down below clearance height.

1 year ago
Reply to  Mike D.

Thank you for this information!

Mike Ostrander
1 year ago

Also, If you go across the border, north or south, you should put your height in meters on that note

Russell Gould
1 year ago

To be honest I do not necessarily believe the height warning signs for bridges. When they replace the black top they can alter the clearance level, lower or higher. They do not necessarily check to ensure the warning sign is still accurate. I had a mishap in the NE with a truck and a stone RR bridge because the clearance on the sign was not what physically existed at the bridge.

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