Hello,
Thank you all for the great feedback, Always great to get positive & creative responses.
Hi Testtube,
Yes I start with 1" 18# HDU, will be moving to using 20# very soon. I try and carve as much out of the base substrate as i can and then layer on top of that, i have tested a lot of different glues over time and i always have used a 100% Polyurethane, I use LePage Premium Construction adhesive, I have used a sledge hammer to test this glue and the substrate failed before the glue did.
One other glue i have been also trying is Coastal Enterprises PB Bond, This works great on Larger surface bonding and is made for the HDU. I don't use this for smaller pieces because it expands.
I hope this helps!