Most caravans and motorhomes are fitted with double glazed opening windows. These windows take an opening window seal that help keep the vehicle warm, comfortable and dry. Replacing this seal is required once your existing seal starts to deteriorate or is no longer providing a sufficient seal. By fitting a new window rubber you can ensure that your caravan or motorhome remains water tight and warm.
This guide from Seals Direct explains how to remove your existing seal, take measurements to identify a suitable replacement and fit the new window rubber.
We sell a range of opening window seals suitable for most caravans and motorhomes. We also sell a range of accessories, such as cover strip fitting tools and silicone spray to help with the installation process.
Video Demonstration
Whilst replacing this window rubber is a relatively straight forward process, there are quite a few stages that may cause confusion if this is the first time you have undertaken a window seal replacement. It is often useful to watch the entire process be completed by someone else, prior to replacing your own window seals.
This video demonstration from Seals Direct runs through the process of removing the existing rubber seal and taking measurements to identify the best replacement section. It then shows how to fit the new window rubber and cover strip.
Step 1a: Measuring the Wall of your Caravan or Motorhome
You will need to measure the wall thickness of your caravan or motorhome before purchasing a replacement section. This is to ensure that you order a window rubber that fits snuggly onto the wall of your van and seals properly to minimise the chance of water ingress and draughts.
To take this measurement, remove the existing seal and measure the thickness of the wall. You can do this by locating the end of your current window rubber and gently lifting it off the panel edge. This will allow you to use a Vernier or tape measure to accurately measure the wall thickness. This measurement should be between 25mm and 40mm.
Alternatively, if you are not able to remove the existing seal, you can calculate the wall thickness using two pieces of wood.
Place one piece of wood under the seal on the outside of the van and the other piece of wood under the seal on the inside of the van. Take a measurement from the outside of one piece of wood to the outside of the other piece of wood. You can then calculate the wall thickness of the van by subtracting the thickness of the two pieces of wood from the overall measurement.
For example, if the overall measurement (A) is 77mm and wood B and wood C both measure 25mm, the wall thickness will be A (77mm) - B (25mm) - C (25mm) = 27mm
Step 1b: Measuring the Sealing Bulb on Your Existing Seal
You will also need to measure the diameter of the sealing bulb on your existing seal. The sealing bulb is the sponge tube on the outside of the window rubber and compresses to create a seal when the window is closed. This measurement should be between 10mm and 14mm.
There are two different styles of sealing bulbs on opening caravan window rubbers. The first type has a fin and the second type has a double bubble. We recommend looking at your existing seal to determine the shape of sealing bulb required.
Step 1c: Identifying the Correct Replacement Seal for Your Caravan or Motorhome
Once you have measured the wall thickness of your van, the diameter of the sealing and determined the type of sealing bulb, use the table below to purchase a new section.
View our full range of caravan window seals.
Step 2: Removing the old Caravan & Motorhome Window Rubber Seal
Open your caravan or motorhome window and carefully note the position of any fittings, such as the hinges for the window stays. Undo the screws so that these fittings hang loose and are out of the way for when you remove the window rubber. The window can either be removed or propped up. You may wish to make several marks close to the original screw holes, so that you know their exact position once the new seal has been fitted.
Start by locating the end of the white, grey or black cover strip and pulling it out of the old window rubber. With the cover strip removed, you should then remove all of the staples holding the rubber to the wall of the caravan. You can now find the end of the rubber and carefully pull it off.
Go around the window opening with a chisel or a flat bladed screwdriver and scrape away any sealant that was left from the old window rubber. After removing as much as you can by hand use white spirit to remove the remainder. Once you have used white spirit you will then need to use methylated spirit or acetone to clean off the oil film left by the white spirit.
Step 3: Fitting a Caravan or Motorhome Window Rubber Seal
The new window seal will be supplied with a layer of non-setting butyl mastic applied to the inside of the outside leg. Carefully position the seal over the edge of the wall on your caravan or motorhome and press hard against the outside leg to ensure a strong bond between the mastic and wall. We recommend putting the join on the side of the window.
Cut the window rubber to the correct length ensuring that the ends are fitted tightly together.
Staple the seal in place using a staple gun to ensure that the seal is held firmly onto the wall of your caravan or motorhome. These staples will be hidden by the cover strip once fitted.
Step 4: Inserting the Cover Strip into the Caravan & Motorhome Window Rubber
Next, fit the grey, white or black cover strip into the top of the window rubber. The easiest way to do this is with the use of a cover strip fitting tool and lubricating silicone spray. Our cover strip fittings tools (CST4335 and CST5015) and silicone spray (SS4363) are available from our website.
To use the tool, lubricate the inside of the window rubber cover strip channel with the silicone spray. Insert the tool into the channel ensuring that the two legs at the back of the tool are securely inside the channel lips.
Insert the grey, white or black cover strip through the center of the tool and push the end back into the rubber under the lips. Gently move the tool forward to lay the cover strip into the window rubber. Once you have been all the way around the window end by overlapping the end of the cover strip over where you started.
View our Cover Strip Fitting Guide for a detailed explanation and video demonstration.
Step 5: Reassembling the Caravan & Motorhome Window Fittings
The final step is to refit all of the window fittings and stays.