Foundations for firewall on tandem garage

[Justthejob]

I recently got approval to convert the back of my tandem garage into a habitable space. I was told that I require a firewall to separate the existing tandem garage in two. The floor of the garage is concrete. If I am building block work on this as a firewall, that is across the width of the garage, do I need to re I force the floor. If so how would this be done. Would I need to dig through the existing floor to lay a foundation,or is there some other method.

[welsh brickie]

use thermalite blocks,half the weight of concrete.Check with building control he may require it to be 225mm thickness instead of 100mm

[Justthejob]

Was thinking of using celcon 100 block, 7.3kg each. Do you think this would be ok to use across the garage. I am assuming that the slab will support this as its a short span, 2.5m.

[welsh brickie]

yes thats fine.