PVC windows using old sash boxes?

[Magnolia Matt]

I have single glazed aluminium windows fitted to the old sash boxes. This was the norm at the height of the aluminium craze. Can I remove just the aluminium windows and fit UPVC into these old sash boxes? One mate says he can do it for me, another says take boxes out.
Problem is some houses in street (Edwardian terraced with bay) have had their bay collapse when complete sash frame/box was removed.

 

[SASHWIZARD]

Why not remove ally windows prepare paint work and fit double glazed timber sashes!!!
They would look much smarter than any alternative but would need more time to complete.

 

[Magnolia Matt]

I'm selling the place so its a cheap tart-up job. Although your idea is a good one, I feel 1st time buyers would prefer the UPVC. The whole street was recently done up with grant money (I didnt want to participate cuz I'm selling & would have to pay full cost) & they ALL have UPVC now.

 

[SASHWIZARD]

In that case i would leave the box frames in place and simply replace the ally windows with plastic,removing the box frames would be a job for a skilled window installer using supporting props etc.

 

[Magnolia Matt]

Yeah. I was wondering if anyone on here had done it this way ...

 

[SASHWIZARD]

Yup i've fitted alot of bays,the problem u have is that the box frames are much thicker (135mm usually) where as your upvc is more likely 60-70mm thick and the overall width of the upvc frame will be smaller.You would need to brick up the excess void then plaster or use timber studs,
plasterboard and then skim.Not forgeting you will need to acro prop the roof above whilst this is done letting the brick or timber work support afterwards.
Replacing the whole window will need to be registered with your local council(for a fee!!!!) where as leaving box frames and fitting new upvc inside these would be classed as a repair and would need no registration(check this with local planning department).

 

[Magnolia Matt]

I'm trying to find if anyone on here has done UPVC in their existing sash boxes .

 

[SASHWIZARD]

Its fairly straight forward,the ally window will be held in by timber liners on the inside,maybe a few screws and silicon sealant around the outside.To measure up remove your timber liners with a hammer and large driver/chisel and measure the ally window,your new upvc window will be thicker so take care taking off the liners rip them down and pop them back on!
When taking the liners off run a stanley down the joins to break the paint neatly and dont forget to reseal the outsides when complete.