Screw thread on UPVC doors

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    Screw thread on UPVC doors

    I got possession back of a flat a couple of weeks ago. This was the one that had the french doors broken into. There seems very little damage to it except that strangely some of the screws securing the adjustable 'keeps' on the secondary door are missing. (These are the things that the bolts on the main door engage with.)

    I just took one of the screws to B&Q, but it is a job to find out its size due to all the nuts being in plastic bags. I managed to squeeze out an M4 nut, and tried it on the screw. It went in but seemed wobbly.

    The thread seems quite coarse, rather like those American screws that hold in hard disks.

    It seems mad that I would find an American screw size on a British door. Can anyone shed any light for me?

    If you have a steel merchants or engineers supplies merchant near you I would try there, they will have a larger range of screws than b&q type shops. (and at a fraction of the price) I use because they are local but I'm sure there must be someone similar near you


      Thanks Grouse.


        FWIW some friends of ours had new UPVC doors and windows installed a year ago and were told (by the installers)to lock them at night not by using the key (more of a risk safety risk if you have to hunt round for the key in smoke/fire, etc), but by pushing the handle downwards, which does indeed seem to lock the door.

        They have been doing this...and were burgled last week by someone who simply pushed the handle down from the outside, inserted a screwdriver to move the locking mechanism and was in the house in seconds.

        Fortunately the insurance company have agreed to pay up.
        'Pause you who read this, and think for a moment of the long chain of iron or gold, of thorns or flowers, that would never have bound you, but for the formation fo the first link on one memorable day'. Charles Dickens, Great Expectations


          I have resolved this problem today simply by removing the steel strip from the secondary door and replacing the missing screws with countersunk M4 nuts & screws.

          I also packed out the door frame keep that the bottom bolts engage with. The door seems a lot more solid now.

          I have run my hands all over the outside of the frame & doors, and can find no damage at all that you would expect a crowbar to cause. Mystery, eh.


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