Fitting Seitz S4 windows to a panel van – Camper conversion

Whether this is standard procedure or my bad luck, the Seitz (Dometic) window I bought came with no kind of installation instructions. There are a few guides on other blogs, so using these and a bit of intuition, this is how I fitted my 700 x 300mm Seitz S4 sliding window.

Seitz windows are essentially two halves which screw together over a surface. Since they are made for caravans with sandwich (thicker) walls, there is a gap of roughly 1 inch in between the front and back of the frames. Therefor, when installing on a panel van with walls only a few mm thick, you will need to make a wooden frame.

To avoid confusion – the screws will not need to go through the frame, the frame will simply fill the gap between the inside section of the window and the van wall.

You will need:

• Seitz window
• Wood approx 1 inch thick (or however big the specific gap is on yours)
• Wood glue
• Screws
• Measuring tape
• Screwdriver and drill with metal drilling heads
• Grinder
• Instant grab adhesive (No More Nails, Evostick etc) (And gun to use with)
• Disposable gloves
• Eye protection
• Jigsaw with metal cutting blades
• Metal file
• Sealant (Sikaflex or similar)
• Metal paint or primer
• One helper (this is a two-person job)

Step 1: Make a frame

To make a frame you will need to measure round the inside edge of the outer section of window –

The outer section of the window with carefully measured out frame fitting round it, with hole of the same size cut in van

I glued and screwed the frame and left to dry over night. Make sure it fits exactly or you’ll be in for a let down when you try to fit! Make your motto: measure twice, cut once.

Step 2: Cut the hole

Now for the nerve-wracking part. Don’t worry – this was the first time I had attempted precision cutting of metal and it all worked out fine! Firstly, make a template of the inner part of the outer section of window – the same part you made the frame from –

Cardboard template, drawn round on van panel with anti-wobble bar cut off

To prepare the panel for cutting into you may have to remove an anti-wobble bar (bottom left) – use a grinder for this but be careful not to slice through the panel! Draw around the template you’ve made (this is also the same size as the inside of the frame you made) and prepare to cut. Make sure to wear eye protection (and mouth if you want to) as small, sharp and rather hot shards of metal will be flying around!

Equip a metal drilling head to your drill and drill close into the inside corners of the window outline. I found a small, thin head drilled through quickest. Then enlarge the hole by working up through the sizes until you have a hole large enough to fit the blade of your jigsaw with metal cutting blade through. You may want to use masking tape to guide the jigsaw and protect the metal outside the outline from scratches. Now, cut the outline out! It might be useful to stick some tape over the cut edges to stop it wobbling about when you cut the final edges.

Step 3: Fit the window

Once the outline is cut, check the window fits in. If not, don’t panic! I actually had to enlarge the hole I had cut by a few mm on the top and sides. It’s doable, but make sure you only let the blade cut forwards – if you put pressure on the side to try and turn it, the blade will snap (I got through two in a pack of three).

If you’re happy the window will fit, file down the sharp edges with a metal file and paint with primer or metal paint like Hammerite, just in case any water or condensation got in, to stop the metal rusting from inside the newly installed window.

We have a hole!

Let the paint dry, then use adhesive (I used Wickes own-brand solvent free instant grab adhesive – in fact I used a hell of a lot for all the insulation too) to stick the wooden frame as best you can round the newly cut hole. This is where you need your helper.

Before your stick the wooden frame onto the metal inside the van, pipe a generous bead of sealant such as Sikaflex 211 around the outer edge of the outer section on window (this will most likely be a rubber seal). Make sure it’s the right way up and get your helper ready on the outside with the outer section of window.

The wooden frame may not stick very well as the sides of vans generally have curvature, so use a hefty dollop of glue and hold the wooden frame in place while person no.2 pushes the outer window section in from the outside. It might be a tight fit, but that’s a good thing! Make sure your helper pushes the outer window section in nice and tightly, you want the sealant to form a tight seal.

As seen before: The wooden frame glued on with the outer window pushed into place, sealant round the edge on the outside

Now take the until-now neglected inner section of window (this usually contains a blackout blind and flynet) and (making sure it’s the right way up) match it to the screw holes on the recently-installed outer section. Screw your screws in most of the way, making sure you screw in adjacent screws to get an even fit. Once they are all in most of the way, use a screwdriver to tighten adjacent screws all the way.

Go outside and wipe away any excess sealant, and/or if needs be, add some more to make sure there are no gaps round the edge of the window. Et voila!

Your Seitz S4 window is installed!