It's a deal between the developer & contractor.
I bought my house during construction period & started the instalment.

Developer will issue letters regarding the progress of the house, whereby the letter will mention: roof, walls, road had completed or half completion & etc.
The letter shall state the material as well (red or sand brick)
But make sure to ask the developer about the material, location, neighbour info, quality of land before purchasing. It's very important. Unless u bought a 2nd hand or lelong house or apartment, thats a different scenario.

I was privileged to sneak in to the site area whereby it's confirmed the contractor had used red bricks on my house. 

arthurlwf,

So what?? 

A) Even if the material is good, the house is built on not so solid ground and the developer had not put enough soil into it and let it settled, you still will have crack wall.

B) Will the house be flooded???

For (A), you need to be very extra careful if the land is ex-tin mine ground.  For ex-palm oil plantation, you need to know whether the house is on the low side or high side of the land.  If it is on the low side, they need to put soil into it and let it settles. 

Dreamer