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Tuesday, December 7, 2010

House Construction 7: Water Proofing the 1st Storey Floor

My architect had chosen "basement style" waterproofing for my 1st storey floor. First, a thin layer of concrete is laid down. Then, a black sticky substance is painted on top in 2 layers. This sticky substance hardens into a plastic membrane that keeps out water. Woe to you if you make holes in the dried membrane when you step all over it during house inspection. Third, another thin layer of concrete is laid down.

In between skype, sms-es, emails and people travelling... a miscommunication happened between architect and builder. Mr Grizzly did not lay down the 2nd thin layer of concrete and the workers proceeded to step all over the membrane in order to tie in position steel bars a few inches above the membrane. See picture above. Step here step there. These steel bars are the reinforcements for the concrete that will form the floor of our house. Now, imagine that if there were holes in your membrane and dampness rises into your concrete floor. What happens?

The steel bars that hold up your floor will rust and corrode.

This is not desirable because it does not make for a lasting house. Ideally, there should be Concrete Layer A (thin layer), then membrane, then Concrete Layer B (thin layer)... and ONLY THEN the concrete floor slab with steel bars inside. The 2 thin layers of concrete will protect the membrane from tearing as workers step all over it to lay the steel bars.

Well... in the end, because the membrane had been compromised, it was decided to use Waterproof Concrete to cast the 1st storey floor slab. Now... even here, not all Waterproof Concrete are same. There are those that come in powder form and mixed on site. The builder will apply it himself. Such types do not come with warranty. Next, there are those that come in a huge cement truck with trained specialist applicators. These come with a 10 year warranty.
Mr Grizzly gave me the type with warranty.