Can I connect a new slab addition to an existing (engineered) slab on grade?
Exisitng engineered pad 24w x 32L (nnot heated), for a garage, and would like to add another slab on grage addition with radaint floor to this garage approx 24 x 40
New configuration of the garage would be in a L shape so i would extend the length of the current garage from 32ft long to 56 ft long (add 24ft) and extend the width of the slab and new part of the garage to 40 ft
Not sure if this can be done as it would technically be 2 seperate slabs (connected or touching) with 1 building on both slabs?
There should be no reason that you couldn't attach a new slab on grade foundation to an existing slab provided the existing slab is not showing signs of frost heave or significant cracking. This page should help-
How to build a slab on grade - a comprehensive DIY guide to frost protected shallow foundations
You would need the slab to be engineered of course, and in most areas you would need an engineer's stamp for permitting. A slab is actually the best way to do it, digging down to pour a footing and frost wall adjacent to an existing slab would undermine the soil underneath. This is an engineering firm in our directory that designs raft slab on grade foundations for the US and Canada.
A raft slab is probably the best way as it is designed in a way that spreads the weight evenly over the entire surface of the floor rather than on a footing, so excavation is just a matter of removing the 6 to 8 inches of organic matter and laying a bed of 6 to 8 inches of clean drainage stone in its place, so you would not disturb the existing slab footing at all.