Loose window handles

[GreyBot]

I live in an old house with UPVC windows dating back to the 90's.
A lot of the handles have started to come loose on many of the windows. I have managed to tighten up quite a few of the handles by just tightening the 4 screws. Others have needed new handles, because the handle it's self has started to fail due to age.
However, the problem I have now is that some of the screws have nothing to grip onto behind the handle, so I have no way of tightening any further.
I tried some UPVC putty, but all it did was fill a bit of the void behind the screw hole, it didn't help the situation at all.
Any ideas please?

 

[crank39]

When you say 4 screws I assume you have cockspur handles then rather than espag, if so you may need to pop rivet using tri rivets or peel rivets

 

[GreyBot]

Sorry, yes, cockspur handles. The screws in the loose handles are just spinning - can no longer be tightened.

 

[DiyNutJob]

Use bigger screws?

Or, insert small wall plugs and use smaller screws.

 

[opps]

Use bigger screws?

Or, insert small wall plugs and use smaller screws.

I am guessing that the uPVC is only 3-4mm, I cannot think of any nylon wall plugs that will be suitable. Regular ones will only expand far into the void. The types that pull up the screw thread and grab the back of the material are normally designed for thicker materials.

The Fischer UX plugs would require a min of 9.5mm thick uPVC.

fischer Universal plug UX 6 x 35 without rim

The fischer universal fixing UX is a plastic fixing made of high-quality nylon. The fischer universal fixing expands in solid building materials and knots in hollow building materials for maximum hold. For this reason the fischer UX is always the correct choice - even with unknown building...

www.fischer.co.uk

 

[crank39]

I was actually only pop riveting some new cockspurs onto aluminium windows the other day where you have to use rivets because the glass is just 10mm or so behind the face, the machine screws had worn away the ali much like your pvc, I suspect your glass is a bit further away so you may be able to use 25mm pvc repair screws which have a larger diameter thread, if not then its pop rivets