Sash box replacement advice

[bob2611]

I have old sash box windows with Alumunium windows inside of them. The sash boxes have begun to rot away and I really need to replace the windows.

A builder next door looking to get in on the job has said the after the sashes are removed you need to brick up the gaps and the sashes have a wooden lintle running at the top which is taken out and not replaced by glazing companies. Once done, you need to plaster around the windows.

I had a few double glazing companies come round they all just say they will "fit" the windows and "make good". When pushed and probed, it seems they are filling the voids with fibreglass and putting a pvc panel to cover the gap.

I am not sure who to listen to or what is good practice. Any advice on getting these windows fitted.

Also, apart from the energy ratings and secruity features, how do you tell the decent companies from the not so decent.

 

[DHFrames]

Your preference at the end of the day. Unless you demand what internal finish you require 99% of companies will finish in UPVC. Personally I don't like it and advise a timber finish instead. Pvc surrounds & architraves will be an eyesore if not done properly.
I think your builder is trying to blag himself the job, under no circumstances would a window company remove the timber lintel (unless it needs replacing). We always pack above the window in timber, this enables curtains poles etc to go back, this is a must if the finish is in UPVC!
Many builders fit windows/doors, some good some bad, unless you've seen his work go for a small local company who'll will take pride in the job and give you the finish you want.

 

[DHFrames]

Bricking up and plastering is another option, great finish once painted but this will limited the option of reverting back sash windows for you or anyone else who buys the house, unless of course if you take back out all the bricks/plaster

 

[crank39]

When I was fitting we always boxed out with 4x2, foamed all the voids, plaster boarded and skimmed the reveals and used bonding then skim for the walls

As for the lintel, we never replaced any, not once. The lintel wasn't part of the existing wooden sash box so why should it all of a sudden become part of the PVC window, I think the builder is touting for more business by trying to scare you