1st, do you already paid them in full? if not, then congrat.... you can hold their payment until they follow the spec and change the things.
make sure there is not additional charges when you want them to change and follow back the spec

2nd, terminated them, and hire another contractor.

Just try to ask, is the specs is so important that have to following 100%? or is only a minor diff? do you try to communicate with the contractor why this is happen? may be there is some problem on site which the person who make the spec do not realise?

4J16??

u mean 4Y16 right   or 4T16

ok, ic, if you already have the specs detail b4 work started and the contractor aware of it, then he is responsible to make sure giving everything acording to the specs, you have a right to ask then to re-do, but is really strong enough or not, then have to refer back to architect, let say architect also say is actually is strong enough, then u can choose want to ask them to re-do or not.

yes..it is Y16 and T16 , don't know where the J came from..too confused..looking at engineering drawings..
also what is pad footing 1200 mm ? is it 3 feet deep and 3 feet wide cement footing for column?

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Added on March 2, 2011, 8:01 am
Mpst contractors in Malaysia like that from experience? When I confronted him, it seems he has not read the specs..or choose to ignore it..

well, from what i know, mostly are actually like that. because if a minor house extention, they will just ignore the spec since they think they had done a lot and no problem so far, and they normally will think architect always giving a spec more then what should they use simply becoz architect not the person work on site.

But if you looking for a formal designer company which have own architect to build a bangalow house, they will of coz following all the spec but of coz the price must be extreamly higher compare to the contractor around.

In ideal world, they sud always refer to the specs for requirements. what is their excuse of not following the specs? its very irresponsible contractor.