Anyone who has locked themselves out of their motorhome or caravan will have discovered how easy it is to prise open the plastic windows. This insecurity is caused by the flexibility of both the acrylic windows and the plastic latches. Chris's comments in the footer explain the caravan industry's reluctance to spend more to eliminate this vulnerability, meaning an aftermarket security device is your only choice.
The Polyplastic sliding window above has enhanced security from UK manufacturer Lock M Out, who produce a range of devices that secure or lock the latches of Polyplastic or Dometic/Seitz windows. 99% of motorhomes and caravans have windows from these two window manufacturers.
Polyplastic windows have just one latch for outward opening windows and one for sliding windows as seen in the photos below.
You only need to buy enough push on devices for all of the bottom latches on your Polyplastic windows. See the detailed product images of the V3A Polyplastic window lock for more information.
The Lock M Out security device fits both left and right hand opening Polyplastic sliding windows. They can be fitted loose or screwed permanently, as photographed above. See detailed product images and information about the PSL1 Polyplastic sliding window lock.
Caravans and motorhomes with push open Dometic/Seitz windows are secured in a second by simply bringing the device down onto the Seitz handle until the button pops through the hole. See detailed product images and information about the MR2 caravan window locking device. Right and left hand devices available.
Lock M Out manufacture two age-related Seitz sliding window locks. The width of the device is the same, but the depth to the retaining catch is further down on the old style window catch used before 2006.
See detailed photos and information about the S4 Pre 2006 Seitz caravan window locking device.
See detailed photos and information about the S4 Post 2006 Seitz motorhome window locking device.
I asked the managing director of Polyplastic why they do not produce more robust window catches. He explained, at length, that caravan and motorhome manufacturers will not pay for more secure latches. Having drawn a blank there I looked and found these practical and affordable add-on security catches being manufactured in the UK, which I have fitted on my own Wildax Europa van conversion and hope that you will too.