Answer
Why is porcelain more expensive to lay than sandstone?
Higher material cost plus a more skilled, slower full-adhesive-bed installation.
In short
Two reasons. The boards cost more to buy than Indian sandstone, and they have to be laid on a full adhesive bed over a primed slurry, with precise cutting, which is more skilled and slower work. Laid wrong, porcelain fails, which is why many firms will not warranty porcelain they did not lay.
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