I assume there is a large price difference in the two quotes. Since this is your customer, any reason why you dont want to quote it both ways. If you are not experienced in installing concrete slabs, get a sub to quote it, and you can let your customer choose the install method he wants[/QUOTE]
By doing/saying this, aren't you kinda like saying "they're right"?
Just sounds to me like you're saying the other companies method is just as good as my way, and I really don't know what I'm doing.
Jim, if your convinced, and I know you are, that doing it your way is the best way, then stick to it, win or lose.
If you offer to put it on a slab, and you have someone else do the slab, or even if you do it yourself, you will always be wondering about it.
Industry standard ICPI methods are what they are for a reason.
I think there were some other good thoughts already suggested, i.e. drainage, etc.
Just my $.002 worth.