Raising floor question

[Morticer]

Hi Folks

I have been buidling a kitchen extension (part old and new) and we would like to raise the floor up to the height of the rest of the house. This is roughly 45mm in the new build (block and beam floor) and 95mm where it joins the old house. I'm planning on using wooden battens/joists (not sure what they should be called when they are resting on the floor!) which need to be screwed in to the existing slab/block and beam. I was just wondering what you guys might use to fix them down? I'm sure I'm going to have to pack some of it out to make the floor level. I was wondering about hammer fixings/rawl plugs/frame fixings as options and whether I could drill through the wood and in to the floor in one operation.

As ever your experience is greatly appreciated

 

[Alastairreid]

The floor should sit fine without any fixings.

 

[Tipper]

Fill any gap under the floorboards with insulation to stop condensation building up within the space.
I used vermiculite recently for the same job. Easy to fill and spread/level to the top of the 'joists'.