Fitting windows to your van conversion

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Fitting windows yourself is a bit scary – you are cutting large holes in the side of your van – but it isn’t actually as difficult as you might think.

The secret, as always, is measure twice, cut once.

Here are a few photos illustrating the process of fitting a Dometic / Seitz S4 motorhome window (eBay⇒) to my van.

1. Decide where the window is to go and mark out the cutting line.

Check the window positioning on both the inside and the outside of the van before you start to cut. Note where the anti-vibration struts are on the inside of the panels – these are a pain to cut through but can safely be removed:

2. Cutting a hole for the window

To do this nicely requires two tools – an electric drill with a hole-cutter drill bit (eBay⇒) and a jigsaw with a metal cutting blade (eBay⇒).

The installation instructions for your windows should specify the size of the hole cutter you need to make the corners.

Here’s how it goes. Corner holes drilled, lines marked and taped up with masking tape (eBay⇒) to prevent the jigsaw guide scratching the paintwork:

Three sides cut now – apply some extra tape to help stop the cutout flapping while the jigsaw cuts the last side. Having a second person to help here is useful – they can hold on to the cutout from the inside to help keep it still:

Once the hole is cut, use a file to smooth down the edges and then paint the bare metal with some red oxide paint (eBay⇒)  to make sure they do not go rusty — you do not want rust creeping outwards from your window frames.

Remember also to clean the metal filings thoroughly from the outside of your van – an airline is good for this if you have one, otherwise a vacuum cleaner and/or a magnet can be used.

(If you do not clean the metal filings off your paintwork, they will embed themselves in the paint and go rusty, giving your van’s paintwork a rather speckled appearance. Don’t ask how I know this… if you do make this mistake, the metal particles can be removed with a car valeting product known as ‘detailing clay (eBay⇒))

3. Building the frame

This stage may differ for different types of window and different types of van body. In this case, the windows are Dometic / Seitz S4 windows (eBay⇒) being fitted to a panel van body.

Because they are designed to be fitted to caravan and motorhome bodies, which are of a sandwich construction and approximately 1″ thick, an additional frame is required when fitting these windows to a panel van, whose walls are only a couple of millimetres thick.

What’s required is a wooden frame, fitted to the inside of the van like this (full details come with the window’s installation instructions). The idea is to make the wood plus the wall of the van around 1″ thick:

4. Fitting the window

This stage is surprisingly easy. All that should be required is to push the two halves together and then screw them together (see your instructions for specific details).

Remember to use some Sikaflex adhesive (eBay⇒) under the outer window frame and then to seal around the edge of it after fitting with some more sealant/adhesive.

This is especially important with panel vans as the sides of these vehicles usually have some slight curvature, which you have to fight against – hence the importance of sealing the gaps.

That’s it! The first time I fitted these windows I was nervous about it, but it turned out to be a relatively pain-free job. I would recommend having a DIY-competent friend to do it with if possible.

Once your windows are fitted, you can insulate and panel around them.

Next: Carpet lining and flooring

Back to Conversion Guide Index

Disclaimer: All material is provided for information purposes and is my opinion only. I can take no responsibility for the accuracy, suitability, reliability or safety of the information in this guide.