Hi V. While it mightn't perhaps be true to say that there is always V.A.T. on a site (the exceptions are too rare to be meaningful), there certainly would be in the circumstances you describe.
This is one area where there was some elaborate avoidance prevalent a couple of years ago; there was a budget change brought in to stamp it out, but it was done without any admission that the loophole was valid, and I think Revenue are pursuing\have pursued the builders involved. I had a builder or two enquiring about V.A.T. avoidance at the time and (more by laziness than strategy) steered 'em away from it. Anyway, the relevant law is:
Section 4(5) of the V.A.T. Act 1972: [I haven't checked if this was amended since, so don't take as gospel]
"Where an accountable person disposes of an interest in immovable goods to which this section applies or carries out any development in relation to such immovable goods and in connection with that disposal or carrying out of development some other person who would not, apart from this subsection, be regarded as an accountable person, disposes of an interest in relation to the goods concerned—
( a ) that other person shall, in relation to the disposal by him, be deemed to be an accountable person, and
( b ) the disposal shall be deemed to be a delivery, made in the course of business, of goods which that other person has developed."
From Revenue Guide (dealing with the "usual" rules for whether a sale of land is liable to V.A.T., in which rules the sale of an undeveloped site would otherwise be exempt)
"It will be seen that whether or not any particular supply of property is taxable depends on the facts of each case and no general rule can be relied on to determine the questionin every case but the following question and answer system may be helpful. The system should not be used in cases of building licences and similar arrangements."
From older Revenue Guide: .(referring to building licences and similar arrangements):
".....it is specifically provided that a landowner who does not himself engage in any development work can, nevertheless be treated as a taxable person in certain circumstances..."......