how to raise a upvc door

[seneca]

We have a UPVC porch door that is beginning to rub at the bottom. The door is UPVC and the frame has a small piece of metal with 2 screws in it. Theis is what the door is rubbing aginst. There are 3 hinges on the side with tiny allen key bolts at the top/bottom of each. Is there any way I can raise the non hinged side by a few mm to stop the rubbing? The door was removed a year ago to allow removal men to get through.
I imagine it should be straight forward to those who know their doors, but with all the bits that can be adjusted I don't want to make it worse.

thanks,

oh, and the weird thing is i rubs less when there's warm weather! I thought UPVC did not expand/contract? Or is it some other factor.

 

[The-brickie]

Sounds like a toe and heeling problem to me, think there is some info on here somewhere about it. and yes UPVc does expand in the warm even more so if woodgrain and in the sun!

 

[denso13]

As the brickie says, good info here http://www.doubleglazing.com/diy_toeing_heeling.htm