UPVC window formers Vs on site made timber profiles

[flanagaj]

When I did a house refurb / extension many years ago, I knocked up window / door opening profiles using 4x2, and the timber reused for first fix stud work when the shell was water tight.  I see that you can now get pre made UPVC window formers that are essentially a former / cavity closer in one.  On paper these look useful, but just wondering whether anyone has first hand experience of them and whether they are worth switching over to.  Just concerned that they might be flimsy and not remain very square and require bracing anyway.

Edited yesterday at 13:18 by flanagaj

[torre]

We used these for 'normal' sized openings (say up to 1500x1500) and they worked really well. Ours were from subframes, made from (cavalok big blok I think) 150mm closers. They were very substantial and came braced at top and corners to stay square, worked well as formers for brick and block.

They have slide in ties for brickwork so feel very built in. Totally different from the floppy bits of plastic and polystyrene of a basic closer.

[Oz07]

On 10/08/2026 at 14:17, flanagaj said:

When I did a house refurb / extension many years ago, I knocked up window / door opening profiles using 4x2, and the timber reused for first fix stud work when the shell was water tight.  I see that you can now get pre made UPVC window formers that are essentially a former / cavity closer in one.  On paper these look useful, but just wondering whether anyone has first hand experience of them and whether they are worth switching over to.  Just concerned that they might be flimsy and not remain very square and require bracing anyway.

As @torre the premade ones are so much better than the off the shelf jobs. I've used them before wouldnt mess about any other way on 150mm cavity construction. 

 

To answer your actual question they are stable enough for the brickies to build in as they go. You may find for doors they will set a profile or straight edge up the reveal also. 

 

 

[Oz07]

What suprised me were the channels in the formers were not filled with foam, just air gaps. I understand pvc windows are like this but I expected eps within the closers having used the off the shelf ones before. They have a bba cert so they must be good for their stated performance.