There was a similar thread where someone asked about % retention from contractor's last payment to cover defects liability.

If you buy a house from a developer, it's 18 months  according to the law (Housing Ministry).

For renovation where there is no proper contract, the situation is a bit tricky. It seems it's like a 'willing buyer, willing seller' situation.   It's advisable to decide before signing the 'contract' how long. Most owners leave everything to the contractor. The contractors seem to dictate the terms. Of course, the contractor would want to collect all their money upon completion. If there is no more money to collect, do you think they would be  willing to come back to do repair work. What if the roof leaks? Or the walls or floors crack?

I think six months is a reasonable period for defects liability.  You have to insist on it or the contractor will tell you there's no warranty/defects liability period (like a forummer-contractor here would tell you).

If you get those contractor who sapu all and do one, probably you can not get these warranty.
But if you get individual specialist subcon, you still can get these warranty. The problem is, you need to spend time to coordinate them.

Friend, there is no need to resort to name-calling if people do not agree with you. You are speaking on the subject from a contractor's point of view.  Of course all contractors would want to collect 100% of the money and not want to come back to the house to attend to the defects if they can get away with it.  It is up to the owners to insist on a retainer before the job is awarded, as an assurance that defects will be attended to. 5% is not a lot to pay to get the assurance.

Of course nothing is free, we don't expect the contractor to come back to rectify defects for nothing. You are saying that it is not possible, no contractor will agree to this condition. Any condition can be negotiated if it is made known from the outset. Just because it is seldom practiced does mean it is the proper way.

I did say there are contractors who are apt to use threats if they are not paid in full.  The situation can be prevented if the condition is clearly spelt out at the beginning.  It's just that most houseowners, being laymen, tend to be too trusting and do not insist on their rights.

You are talking about interior design & interior fitting-out work where the problem of post-completion defects appearing is not such much a problem (being withn the house) compared to building works which involve a host of different trades. Common problems include roof leaking, plumbing problems, cracks, waterproofing problems, electrical problems, poor finishing, etc.  I don't suppose you deal with these problems much if you are only handling the interior works.

I don't know what experience you have in contract administration but proper interior work is also based on a written contract with all the conditions, drawings and specifications for the contractor to follow. All these formaliites are done away with for the 'smaller' renovation contracts where the arrangement between the owner and the contractor tend to be very informal.  However, in practice, renovation jobs are worth tens or hundred of thousands where, relying merely on  informal arrangement and trust would not work. It's not so simple as just buying a set of kitchen cabinets or wardrobes.

Vetkin has said that most renovation jobs go awry towards the end, why? There's something wrong with the arrangement. Conditons are taken for granted, not dealt with before the job was awarded, the contractor has a free hand,  impose conditions which are one-sided. Still, without a proper written contract, there is still an implied contract if a dispute cannot be settled and the case goes to court/tribunal.

I don't see the need to reveal my credentials, suffice to say that I have been involved in builiding projects for decades, particularly in dealing with housing projects for developers are well as individuals from beginning to end.