greenhouse glazing

Hi everyone
I've had a metal framed 6ft x 4ft greenhouse for ~12 years now. During that time, many of the original glass panes which were supplied with the greenhouse (I could have opted for polycarbonate with this greenhouse) have been damaged mainly due to bad weather and the occasional football from over the fence. As glass prices have gone up considerably in my area, I've replaced the glass with 4mm thick polycarbonate sheeting panels. The standard ~2ft wide panels are held in place by rubber lined channels on the inside and W clips on the outside.
Normally everything is fine, however during the recent gale force winds the polycarbonate has been flexing, leading to one panel being completely blown out of the frame along with it's W clips when I opened the door.
As the polycarbonate isn't as rigid as the original glass, I was just wondering if anyone else has come up with a way of holding polycarbonate sheeting more rigidly within a greenhouse frame? Does anyone know if there are different clips available that are more suited to polycarbonate?
One idea I did think about would be to install some side battens, perhaps made of plastic and fasten these by drilling through the sides of the metal frame along the length of the panel.
Any ideas welcome!
Thanks
Paul
Posts
Thanks Gertie grass that sounds like a good idea: I'll have to take a look to see if its a workable solution in my greenhouse.
As a matter of interest, how many holes did your husband drill for each sheet and what size are your sheets (the ones I used replaced two standard glass panels so are ~4ft long by ~2ft wide)?
Gertie grass: just as a follow up to this, I've taken a look and can see how your method works for sections along the greenhouse, but what did you do when you reached the ends of the greenhouse? Did you have to drill holes into the frame to work the cable ties around the corner struts?
Many thanks
Paul
Can I suggest using garden wire instead of cable ties? More flexibility and that would be stable in UV light.
Gertie grass: that would be excellent - many thanks. Paul.
A spot of clear silicone in each corner and middle both side of the sheets will hold the sheets in place.
Gertie grass: thanks very much to you and your hubby for going to the trouble of taking and uploading the photos: this looks good to me so I'll give it a go.
Steve the Gardening Vet and Andy19: many thanks for your advice as well.
Cheers Paul.