If the rear extension is mainly on ground floor should is ok. The contractor need to locate the house rear beam and get the old"reinforcement bars" on the beam, join the bars to the new beam. So this will ensure the new wall and old wall will not crack and have hollow holes.  My mom house had this problem when we pay the contractor do the job and he did not tie the bars to the original, now to fix it will be costly. Just live with it.  Don't go for cheapest, go for quality and price matching, and ask why is more expensive how they do it.
My rear extension "maybe over done", 4 footing, each footing connected by a beam in the floor.  Than top beam. Next time i need, just add brick and can make 1st floor.  Also is RC slab, not normal clay roof

Agreed but maybe diffent method cos only for ground floor.

But normally tiang goes 4 ft deep 2 ft wide underneath. Sth like tat anyway

Agreed but maybe diffent method cos only for ground floor.

But normally tiang goes 4 ft deep 2 ft wide underneath. Sth like tat anyway

sl2007, Thank you for the suggestion. Water proofing will be done for all expose RC slab. The RC roof is completed and the workmanship is acceptable. I can only wait for few month to make sure no crack. This i will hold the payment until 3 months later.

Will do water proofing after all other wet work complete.

Indeed i saw them hack the existing ground and construct a concrete with rod steel to merge with the existing ground with the new wall.

If you are using "expose type" water proofing system, then you need to get Specialist Contractor to do it and request them for a Warranty...

Is you RC Flat Roof concrete casted in one-go or else? You need to ensure all joint are well done...

Good luck to RC Flat Roof...

TQ. Yes, is all expose type and casted in one goal, with proper gutter and level to allow water flow out. The contractor will guarantee of leak free, and I'll also make sure all the joining are leak free.  Think they will be using

Funny, i remember many years back they use water proof cement , now they use waterproof compound.

Hi bro,

Is the final outcome of the Steel Rod before pouring the concrete ?

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Added on June 22, 2011, 11:29 am

You are welcome... Well I not too sure how good is your SC workmanship during the concrete casting... May I know how thick is your slab?

Based on my experience, the Water Proofing compound required a precise workmanship to prevent water leakage...

RC Flat roof need to paint with weathershield paint or not? or paint with any other material?

thanks

Now I know why it only amounted to RM6k for your Kitchen Extension....

BTW, does it include plastering, painting, roof, ceiling and etc wet works..?

Last i measure is 4"+, when they making holes for WC (after my wife want to relocate the WC again).

4"+... Acceptable... Anyhow you required to add a protective screed over the waterproofing....

Not required, but waterproofing is a must.