Garage floor and oversite thickness

[williamglossop]

Hi

I have an attached garage at the side of my house. I am demolishing this to have a new garage built that is 1 meter wider and it will have a bedroom above it.

The plans have been approved and it states the garage floor will be 100mm conc (thickened to 350 at the threshold) on top of 150mm consolidated hard-core with sand blinding and 1200 gauge DPM..... for a bloody garage floor. Anyway, the existing garage floor is 20 cm thick..... is it really necessary to hack it all out just to recast it with the additional width..... it would be much more economical and environmentally friendly to leave the existing floor and just add new concrete to widen it........

Thoughts? Would a building inspector agree to this? Given that is a non inhabited space.

Also, the last third of the garage will form a dining room...... timber suspended floor. Would the existing concrete from the garage be acceptable as the oversight under the joists.... provided I have the stipulated 150mm clearance.....

 

[Old Salt]

My mate had a garage floor extended (diy) and 10 years later dug it up to relay it.

 

[^woody^]

You can extend the slab. Use some 12mm rebar as ties. Ideally your designer should redesign this.

I can't see how the suspended floor will work with the garage floor unless there is a massive difference in floor levels. If there is, then yes the slab could form the oversite.