The warning by United Nations Children's Fund (Unicef) comes after the AJ revealed that the work of a RIBA-backed building charity was being scuppered by local corruption ( Chaos hits British students providing tsunami aid in Sri Lanka).
Confusion over where houses could be rebuilt, a lack of land deeds, the soaring cost of charges and the political situation have all contributed to delays, says the organisation.
Unicef's Gabriela Elroy said: 'Overall I am a bit puzzled that the quality has stayed low sometimes, given the amount of money that has gone into it - and the amount of work.
'The quality of buildings, the quality of work generally - why is it not higher?'
More than 850,000 people on the Indian Ocean island were made homeless after the disaster on 26 December last year, sparking one of the biggest relief operations in history.