Always measure from inside.

Remove any internal trim around the window to reveal the existing window. Simply measure the existing window. If the existing window is a very tight fit, reduce the overall size by 5mm to allow for easy installation. 

Do not worry if you have rounded corners, these can easily squared off using a hand held oscillating saw. The corners do not need to be 'professionally squared' as the external overlap of the upvc window frame will cover the corners and therefore will not be seen.

The windows can be two ways dependent on the finish you require.

• Screw Fix: If your wall construction differs than the above wall thickness, or you'd prefer to trim the internal surround of the window with the existing timber or an new timber beading then you can fix them using screw fix through the depth of the window frame into the timber subframe of the window. Simply open the vent and screw through the frame

• Aluminium Fixing Kit: Installed by knocking an aluminium fixing bar into the specially designed window, giving a secure clamp fix finish. The fixing bar then doubles up as an internal trim which sits flush to the inner wall. This is suitable for wall construction of 38mm or 53mm. 

• You will need to seal the odd leg frame (external lip) with non drying sealant silicone. As the caravan is constantly moving, if you use standard silicone, it will crack and leak over time. You can also use a neoprene foam tape.