How to fill void above door lining

[AFT4B]

So I have had door linings fitted and to my surprise the gap above is massive!

The walls are being float and set.

What’s the best way fill this gap?

 

[Wayners]

Easiest is 3 wooden blocks the same width minus 25mm less for plasterboard.
One in the middle and either side or just one big peace.
Got anything laying around you can stack to make thick enough?
Stick to the underside with polymer grab.

Something like that.

Oh. Set wood back a bit to allow for plasterboard hence the 25mm less.

I'm not a fan of float and set on those thermolite blocks

 

[noseall]

So I have had door linings fitted and to my surprise the gap above is massive!

The walls are being float and set.

What’s the best way fill this gap?

View attachment 414565

Float and set on aerated blocks? Are you mad?

Screw a piece of timber to the top of the casing then fix plasterboard to the timber.

 

[Deluks]

Float and set on aerated blocks? Are you mad?

Maybe he's a bit Dence?

 

[phatboy]

I had the same situation. What @Wayners says is roughly what I did. Construction foam as the lintel was rough to attach a length of timber, but left a small gap between it and the door lining to reduce the chances of cracking when door is slammed.
Then fitted 9.5mm plasterboard over the wood, and lapped it 100mm over the lintel and either end, with some Sticks Like behind the overlapping bit. This way the chances of cracking are greatly reduced (And 2 years on nearly there are no cracks). The 9.5mm board should be roughly the same as the hardwall or sand/cement layer.

Good luck floating over the thermalite, we have 1 wall of thermalite that was floated after some special primer from PRB. Still covered in random annoying hairline cracks, which I'd overboarded the lot now.