glue and fiber will be leaking in a few years too. my cousin house use this.
fiber + glue + waterproof cement (middle )+on top is the black petrol? also leak after few years

that why..i dont encourage using slab cement..even though you hv apply water proof how many layer, still leak after year....you must learn/know the behaviour of cement......there is a technique to avoid leaking though.

Hi Timjason,
Might to share the technique? Thx

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Added on May 11, 2012, 10:55 amIs anyone know the price for roof tile psf? 10x20 ft.

This post has been edited by xerox1234: May 11 2012, 10:55 AM

For those who are doing extension for concrete roof, get waterproofing that is added to concrete mix before pouring. Those that you buy off the shelf, there are no warranties because they only guarantee the product, but they cannot monitor how you do it.

It requires proper mix ratio, especially the water content. Also, to minimize the risk further, ensure the slab has sufficient gradient to fall towards the RC gutter where the rain water down pipe is. If you are planning to utilize that area and requires it to be flat instead of with gradient, then add waterproofing to the cement screed before tiling works (assuming there are tiles).

Cementaid is one option you can opt for.
http://www.cementaid.com/product.htm#waterproof

If you want double protection, before screeding, apply a layer of Proofkote before screed on the dry concrete slab. Then ensure the screed mix is added with waterproofing. Then tile the whole area.

Heard so many complains on leaking for concrete slab, is there anyone that don't have leaking problems for concrete after few years that can share ?

i can't take photo, it is too high for me to take photo.
trust me, rebuild roof tiles is the proven way.
Build concrete slab is my major mistake, very regret.

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Added on May 11, 2012, 4:11 pmi agreed, it is too much maintenance for concrete slab.


This post has been edited by esoo88: May 11 2012, 04:11 PM

lucky you have already put the roof tile.

when i saw people doing concrete slab...for me i know they make major mistake. This is because many contractor do not know the right way of making concrete slab...for them the important is finish the job.

What you said is the most accurate reason why concrete slabs leak. Concrete in itself is porous. It will absorb water/moisture continuously. That is the nature of concrete, irregardless of concrete grade. If rain is continuous, the concrete will absorb till it is saturated and can absorb no more. Eventually, all the moisture/water it absorbs will have to follow law of gravity and it will find a way out of the soffit of the slab.

From my preferred option till the least desired option.
1. Waterproofing added to concrete ensures none or minimal leakage issue.
2. If the slab are already done, then waterproofing should be added to the cement screed. Then the screed should grade to fall towards the RC gutter.
3. Or you can apply waterproofing on the slab, followed by screed.
4. Never expose any waterproofing material to weather or human traffic. It won't last. That's why they should be added to concrete or add to screed or protected with a screed layer. Best would be to have tiles after that.

Maybe later I will post a picture of what a normal grade 25 concrete with and without waterproofing will do.

This post has been edited by matthewctj: May 11 2012, 05:46 PM

yes, it required proper maintenance to maintain concrete slab, however over the years after sunlight and rain exposed, the slab will be degraded, then you will see leaking start surfacing.
Good waterproofing will last longer, bad waterproofing will lead to faster leak, it just matter of time.
Nobody can guarantee this, with roof tile, 1 piece break, just replace 1, much simpler.

Hi Xerox1234,

PM me if you want the right technique.


The price of normal roof tile eg Monier about RM2 per piece. For 10x20 ft you need about 300 pieces of tiles.

Is it the skill or the technic doing the concrete roof is not proper cause it leak? Or it is natural of the concrete overtime will leak?

My water tank area is concrete roof expose out for 14yrs. No nothing leak. Beginning have some concrete paint mean for waterproof. And it last till now.

Both skill and technique is essential. You can't have one without the other, especially when it comes to avoiding leakage.



The above picture shows 2 grade 25 concrete sections after several drops of water was dripped onto it. Within minutes, the one on the left absorbs. As you can see on the right, the droplets remains. That's because that block of concrete was added with waterproofing compound.

I would not say that concrete overtime will leak. It is porous by nature. The picture only shows droplets of water. Imagine a slab which is expose to rain water and without water proofing. The concrete will absorb water bit by bit continuously. Where does it go? It goes into pores of the concrete. Now before it even has time to dry, it rains again next day. Eventually, the concrete will be so full of water, it has to go somewhere. That's when you will start seeing moisture and drips of leaking water from wherever the concrete is the weakest or have signs of shrinkage cracks.

But if your flat roof is well graded for water to fall towards the gutter or rain water down pipe, the risk for leakage is minimal. That's my experience with flat roof and also my opinion

please share what is the "waterproofing compound" you add.

In that picture, it was Cementaid 3CC.
http://www.cementaid.com/product.htm#waterproof

never heard this product from hardware shop.
where to find?

Good Share

how does pu grouting be applied in bathroom where the floor is all covered with ceramic tiles? need to hack tiles to apply pu grouting?

I made concrete slab for me to walk around my second story, but since it still leaks and also even after waterproofing, it will leak in the future, will tiling the whole top with tiles solve the problem? (no roof balcony).

This post has been edited by jojozep: Jun 27 2013, 06:02 PM

anyone use RC gutter on roof tile. good or bad. TQ
recently apply permit got 2 option. GI gutter and RC gutter.