Oz07

Some caulks say its the paint that cracks with the movement not the caulk. Don't know how true that is. Ive been using the crown own brand with a green label not sure if good for you though.

Did you have to pay them or did they just accept being blown out? Maybe I'm a control freak but I always find they need heavy handed steering! That said i never used any of the more expensive firms perhaps these are better?

How thick are your boards. 3mm feels more like a scratch than a groove. Id be looking for more like 6mm you will have to do a test piece see what you prefer. I don't think sockets will look bad with the grooves going into them.

@craig I was talking about small joinery manufacturers. They aren't getting testing done on their system if the bulk of their work is bespoke. Decent upvc beats timber then? Even without any special glues for the units or filling in the chambers. I honestly haven't seen alu spacers on newbuilds in over a decade. I reglazed some of a 30+ yr old timber conservatory the other week and that was 4:6:4 aluminium spacer

I think most units for new windows are specced with warm edge spacers nowadays aren't they? Interesting that timber normally beats upvc. How do the smaller manufacturers (particularly timber with big profile manufacturer back up) calculate their u value? From my experience they just quote the unit u value. I know the accoya performs well thermally. Are other timbers the same?

And what is a reasonable target to aim for? Excluding passive house craziness

Well the law changed last week and our new application has been submitted. Ready for the long wait now...

Interesting. I'm sure when I looked into it the cost difference of triple glazed windows was never going to pay back the energy savings over double in the life of the windows. Unlike single glazed to double where they do save you money. The improvement wasn't as drastic with 3g vs 2g. That rules them out for me although @JohnMo said it was more a comfort thing.

But the custom ones come with welded joints. How do you keep the strength? What brand did you use?

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.

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.

Do the installers glue the unit in when window fitted then or do they come factory glued?

I've also cut sections out before and noggin between

Just looked. Glued glass to sash. Must be expensive if unit fails or gets broken? I think that would put me off

What makes a better profile?