Old Velux Window Codes

Old velux window codes flashings

Old Velux window codes

This page contains a list of older Velux window serial numbers and window codes to help you identify spare parts or the modern equivalent replacement.

Old Velux windows

Velux are always making improvements to their products which is one of the reasons they have been around for so long, I know from a fitters point of view there always seems to be some sort of tweak or improvement made in either the product itself, or the way a window installs. This improvement over the years will obviously leave some older style Velux windows outdated in terms of off the shelf support unless you go back to the manufacturer direct or a specialist spares and repairs company with a Velux serial number or window code.

However new off the shelf Velux flashings can be made to fit older windows in many circumstances regardless of what you may have been told.

Where are Velux window codes located

The window codes are found on the top right hand edge of the roof window when you open it, the data plate will give you two important pieces of information.

The location of Velux data plate and what the codes mean

1. The type of window – If the window model is GGL for instance it would be pine centre pivot.

2.  The window size – As shown left, 304 would be 78cm x 98cm and pictured bottom window code 4 would be 114cm x 118cm


Common older Velux windows would be

  • GGL Centre pivot Pine window
  • GHL Top hung Pine window 30o maximum opening
  • GPL Top hung Pine window 45o maximum opening

Common older Velux sizes are listed below…

Here are the Velux window size codes

Sizes relate to external window frame measurements in cm

old velux window codes and velux serials explained


Click to enlarge






Old Velux window sizes serial numbers and number codes

Remember window sizes are for the external window frame not internal measurements

  • Window size 55 x 78 code 102 or CO2
  • Window size 55 x 98 code 104 or 6 or CO4
  • Window size 78 x 98 code 304 or 1 or MO4
  • Window size 66 x 118 code 206 or 5 or FO6
  • Window size 78 x 118 code 306 or 14 or MO6
  • Window size 78 x 140 code 308 or 2 or MO8
  • Window size 138 x 98 code 804 or 7 or UO4
  • Window size 114 x 118 code 606 or 4 or SO6
  • Window size 98 x 160 code 410 or 3 or P10
  • Window size  134 x 140 code 808 or 8 or UO8


Velux window blinds and how to fit them

Please see this page to see all the available window blinds and how to fit them Velux window blinds

Velux spares

Having fitted many windows, a big part of that can be maintaining an older roof window. Sometimes either with sheer age, or from a badly installed flashing set roof windows can leak, and if you find yourself in this situation you can contact Velux support for spares or a third party roof window company for spares or repair.

Are old Velux windows compatible with new flashing kits?

Roof window repairs

Can I get a new flashing set to fit my old roof window,  lots of people have asked me this in the past, and often the answer is yes.

Nearly always you will be told that you require a dedicated flashing set from Velux themselves, these are normally 3 times the cost of the equivalent shop bought flashing kit and whilst this is technically accurate you would be surprised how easy it can be to fit new flashings to and old Velux window with minimal fuss.

Fitting Velux flashings to other makes of roof window can also be done if you are having trouble getting hold of flashings for that particular window, check the external window frame size first though to make sure of a basic fit. Roof windows such as RoofLITE, Keylite and Duratech are good examples of this amongst others, obviously on some makes of roof window they can require a little bit more modification.

Fitting a new flashing set to an old Velux window

Instead of using old Velux flashing kits, here I’m installing a new Velux EDZ or EDW to an old GGL 308 which at the time would have had the EDW 308 1000Z flashing when new. The cost of the original flashing kit from Velux ( £152.87 ) + postage makes the repair too expensive to make economic sense, especially by the time labour and materials are added. For those interested you could also fit the newer EDP plain tile flashing set, but it’s a little bit more involved and I would not recommend this unless you are quite confident with roof windows, or have previous experience with the EDP flashing set so you know where you can afford to cut and fold any excess metal on the trims and soakers.

How to fit new flashings to old roof windows

Luckily in this example there is no plasterboard to foul the views, however I’m going to Photoshop some in so you know what to expect if you are replacing an old flashing set on a plastered window.

old Velux window frameThis would be your view of the window frame if the Velux was plastered.

Picture in picture, the window code plate taken from the top of the window itself.

Click to enlarge


Obviously this may alter your plasterwork if you have to raise or lower the roof window, in most cases you will be probably lowering the window frame so the plaster can be cut back neatly and there should be no need to re plaster. Another option is to use a plastic or wooden trim around the edges underneath the frame to mask any gaps.

How to repair a Velux roof window

If you were to remove the plasterboard, this is what you would see inside. The arrow pictured below is pointing to your biggest problem in fitting the new Velux flashing set to your old window, window frame height. What we need to do is raise or lower the height of the frame itself to match your new flashing kit.

If you have a leaking Velux roof window or leaking other brand of roof window please read the Fitting a Velux page for correcting other common installation mistakes which might include roof pitch, membranes or badly fitted flashings.

old Velux window height adjustmentWith the plasterboard removed, the gap above the arrow shows the height of the frame in comparison to the roof joists. This will probably need to be raised or lowered for your new flashings to fit.

Picture in picture is the original frame height instructions. Click to enlarge


Replace old Velux flashings 

If we now place the full new flashing set loose on top of the roof next to the window frame, once seated we can easily see any height difference and simply measure it ( Pic B ). With this number we then either raise or lower the window frame by that amount so that the new flashings fit nicely. In this case the window frame needs to be lowered 17mm or  3/4 of and inch ( Pic A ) you may of course be lucky and no adjustment is needed but this is rare.

old Velux window frame height adjustmentPic B – Full flashing set is placed onto the ready stripped window frame, in place but unfixed to allow checking.

Pic A – Window frame pictured left and the height adjustment slots.

Click to enlarge


Velux EDZ or EDW falshing set window flashingsVelux EDZ Flashings

Pictured are the new flashings used for this old Velux window using the same style of flashing that the original window would have had, but new and off the shelf. EDW are virtually the same but with a larger foam profile should you need it.



Fit new flashings in old Velux window

Your new flashings will now seat nicely, a couple of small cuts to the bottoms of the side flashings may be required but this will not compromise the integrity of the waterproofing at all. It should now be just a matter of re tiling the window to make good. To see a video of the process of tiling a plain tile roof into this flashing set please click How to install a roof window and scroll forward to the last 2 minutes. ( opens in new window )

new flashings in old Velux windowYour new flashing set will be a bottom, two sides and a top flashing as seen above.

All other parts are classified as window trims and will remain original.


Your old roof window will now be waterproof…

Can you varnish a Velux window ?

How to varnish a Velux window …

Sometimes when the varnish on the roof window starts to look scratched or a bit tired, it can be a good idea to re varnish it. The best way to re-varnish the timber surround is a technique that was taught to me by an old decorator with the most awesome varnished garage doors I have ever seen. Instead of sanding the varnish, use fine wire wool and gently rub the top surface of the old varnish with it, this is gives far less deep abrasion and will leave a fantastic gloss finish when finished with either a satin or gloss varnish.

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