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How to Measure RV Skylight: 7 Simple and Easy Steps

Written by Philip Lopez / Fact checked by Paul Lemaire

how to measure rv skylight

If you want natural light and ventilation in your RV, then a skylight will do wonders. This window can show the stars at night and even be used as an emergency exit. Since this kind of window doesn’t come in standard measurements, you need to learn how to measure RV skylight properly before installation.

It’s actually easy-choose the perfect spot, then get the dimensions. Find the most suitable RV skylight and install it cautiously. Learn more about the steps below, but first, let’s enumerate the things you’ll need.

Table of Contents

What You’ll Need for This Tutorial


1. Tape Measure

You’ll be needing a tape measure a lot in this tutorial. For one, you’ll be measuring the interior of the cabin area from one point to another to get the RV roof thickness.

We recommend a steel tape measure because it’s quite flexible to maneuver. It extends and retracts very conveniently.

If you can’t find a tape measure around, look for a yardstick or ruler. Although you can utilize a standard tape measure, it’s soft, making it more difficult to use.

2. Ladder

A ladder may come in handy when you’re measuring the RV skylight. The location for your RV skylight will probably be too high to reach from the ground, so a step ladder will give you the additional height you’ll need.

You can choose between a front step ladder or a twin step ladder. A front step ladder only contains rungs on one side to keep the ladder stable as you climb. For me, the twin step ladder is safer as it contains rungs on both ends.

3. Pencil

To mark the measurements, you’ll need a pencil. A carpenter’s pencil is perfect for this job as it draws clearly on wood and remains sharp longer.

4. RV Skylight Frame

You also need to consider the RV skylight frame that you’ll be using to fit into the available space on the roof.

There are three kinds of frameless glass panels available:

  • Acrylic domes
  • Safety glass panels
  • Polycarbonate sheets.

Acrylic domes are the most versatile as they can be used both outside and inside the vehicle. Meanwhile, the other two options can only be fitted indoors.

  • The flat-tempered glass skylights measure 14-72 inches wide and 16-96 inches long. To get the accurate measurement, determine the sizes-flange and dome.
  • For a rectangle-shaped skylight, the small dome measures around 14 x 14 x 14 inches and an 18 x 18- inch flange size.
  • The largest rectangular skylight dome measures about 30 x 30 inches and a flange size of 34 x 34 inches.

The dome and flange sizes may vary for every model.

Step-By-Step Instructions


Installing RV skylights isn’t as easy as attaching a painting to the wall. This task requires accuracy at every angle.

#1: Pick The Perfect Spot

The first thing that you should do is to pick the right location for your travel trailer skylight. Choose a smooth area without sharp objects that might puncture the skylight during the fitting process. Of course, the spot should be where the sunlight hits directly for more natural light.

Ideally, the perfect spot should be the thinnest part without electrical wires.

#2: Determine The RV Roof’s Thickness

How deep the skylight can be installed depends on how thick the RV roof is. Therefore, you must measure the thickness of your RV roof. Be careful when setting up the ladder inside your RV. Now, measure the interior of the cabin area from one side to another with the measuring tape.

#3: Decide The Depth Of The Skylight

Once you know where to place the RV skylight, identify the depth of the skylight. It is an important figure to allow correct installation.

You can measure caravan skylight depth from the interior of the vehicle to the roof’s outside edge. Reduce the number by ½ inch to leave space for the frame and the skylight.

Some people want the skylight to sit flush with their roof instead. In that case, we can measure starting from the floor joists or ceiling down.

#4: Take The Available Sizes Into Consideration

After you measure a skylight depth, get the width and height of your RV. This will help you find the skylight that fits best.

For your information, the common RV skylight sizes are 27 x 30 inches or 29 x 36 inches. If none of these standard sizes fits, consider getting a customized skylight.

#5: Get The Desired Frame Dimensions

As mentioned above, we can pick among three choices- acrylic dome, safety panel, and polycarbonate sheet for a suitable frame. Once you’ve decided what type of frame you want, get the measurements and buy it.

Refer to the product label dimensions or call the manufacturer to ask for recommended frame size that suits your vehicle type.

#6: Measure the Roof Opening

Using your tape measure, get the dimensions of one side of the roof. Measure the other edge to ensure that the measurement is accurate. If the measurement goes around 6.5 inches, round down instead of rounding up to get a close fitting.

If you have no roof opening, you might need to create a roof opening for the installment of your new RV skylight.

#7: Buy The Suitable Skylight

Once you have made all the measurements, it’s time to get the most suitable skylight that fits into your roof’s dimensions. Check the dimensions of the manufacturer’s product specifications.

Also, consider your budget. The polycarbonate sheet seems to be more expensive than acrylic domes because they provide more UV protection.

#8: Measuring Existing RV Skylight

It’s easier to measure the current RV skylight for replacement. First, remove the screws from the metal retainer frame. Next, pop the frame up from the base while leaving the plastic underneath.

At this point, get the length and width of the plastic’s flat edge with the steel tape measure. Likewise, get the flange dimension on the skylight. Normally, the outer and inner domes are secured together with foam tape.

Most of the time, the overall length and width of the plastic are the same. The flange on the interior dome is a little larger, about 1-½ inches.

Tips for Measuring RV Skylight

  • Clear the space where you planned to install the RV skylight
  • Look for an assistant to help you measure the skylight, if possible
  • To make sure that you get accurate height measurements, measure the ceiling in three various areas
  • Consider any extra space you might need around it when measuring for the size of the skylight
  • For the installation of multiple skylights, get the measurement of the center first

Benefits Of Installing an RV Skylight

Getting an RV skylight installed offers a lot of benefits. This includes:

  • Energy Efficiency: In the long term, installing a skylight is economical. Since you’ll be getting more natural light from the skylight, you’ll be saving a lot on electricity bills.
  • Improvement in The Mood And Health: Travelling means being out in nature. And of course, we should make the best out of it with a gorgeous view of the sky while resting inside the cabin. Looking at the blue skies can also uplift your mood in the daytime. Exposure to natural light also offers good health benefits to the bones and muscles.
  • Good Ventilation: The skylight can be opened to let the cool air in, promoting good ventilation when the RV interior gets a little stuffy. When RVing near the sea, you can enjoy the sea breeze when you open the skylight slightly. Of course, you’ll need to close the skylight when it starts to rain.
  • Emergency Exit: The skylight can also be used for emergencies. When the door is inaccessible, you can open the skylight and make your emergency exit.


Now that you know how to measure RV skylight, we hope that you can enjoy its full benefits. Adding a skylight is less labor, but it requires accurate methods. It would help if you got the skylight’s outside flange to flange measurements.

Have you tried measuring an RV skylight? Let us know in the comment section below. Please share this article with your friends if you like it.

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