The best advice that someone gave me is to include a full house inspection as a clause in the OTP. I.e - OTP is subject to a favorable home inspection. The inspector will also check the plans in detail. It allows you to lock the seller into an offer while you can get out of the deal if major issues are found.
And include a separate clause about the plans.
The "favourable home inspection" clause is obviously of value, but it needs a bit more fleshing out.
What constitutes a favourable inspection?
No defects whatsoever?
Defects with an estimated repair cost of less than X?
Assuming the purchaser is responsible for arranging and paying for the inspection, which seems sensible, the clause in any event shouldn't be written up as a suspensive condition as suggested in the post above, but rather as a resolutive condition. Otherwise if the purchaser neglects to instruct and conduct such inspection the contract could be voidable as the inspection never happened, or the parties could become embroiled in a tacit fulfillment matter.
In order to protect both the buyer and the seller, and to ensure that the contract accurately reflects the mindsets of both parties at the time of contract, the clause should be worded something along the lines of:
"The purchaser undertakes, at his own expense, to commission an inspection of the property in order to confirm that it is free of defects, save for those which have been disclosed by the seller and attached to this agreement of sale and noted as Annexure 'A'.
The purchaser further undertakes to furnish the seller and/or the seller's conveyancing attorneys with a copy of such inspection report by no later than 12h00 on DD/MM/YY, failing which this clause shall be deemed to have been fulfilled and will no longer be of any force or effect"
It would also help to lay out in writing what the way forward would be if further defects were indeed to be discovered in the course of this inspection.
Point of the matter is that these type of clauses need professional legal input regarding their wording, or they can lead to unanticipated legal disputes and actually muddy the waters instead of protecting anyone.