Hello all,

My contractor ask me to go get the iron reinforcement bar for the kitchen concrete top.

I later googled the name for the reinforcement bar and I believe it is called BRC foundation mesh or something close?

So my question is for 12ft kitchen concrete top, is 6mm or 12mm sufficient for reinforcing the concrete top? Contractor said 6mm though.

Can any sifu advise please?

Generally bigger is stronger, but in the case of REO mesh the size needs to be in proportion to the thickeness of the concrete and the use, in this case 6 mm is plenty strong enough.

Sydneyguy: thank you for the feedback! If I do not manage to get the mesh, then will either iron or steel rod with 6mm will be also okay?

BRC is readily available in many of the construction hardware stores. They are all over the place.

Get the ones that have closer spacing. The A series usually space the reinforcement 200mm apart and the B series closer at 100mm. Not that the A series is not adequate, but the closer spacing B series can help to reduce cracking of your counter top concrete.

Also, you mentioned that the top is 12 feet long. I assume that is the distance between supports beneath the counter top. I would suggest you get your contractor to drill some holes in the wall along the 'long' side of the counter and install some bars coming out of the wall to overlap with the reinforcement in your counter top. This will help provide further support to your top and also reduce the probability of cracks at the junction between your counter top and wall in the future.

If you really cannot get the BRCs, they should also sell R6 reinforcement bars. These are 6mm diameter round bars that is used quite commonly to make the rectangular reinforcement (we call it shear links) for concrete columns and beams. You can get this and ask your contractor to cut and assemble the mesh on the counter top himself. This is actually better because you can cut the bars to suit the shape of your sink opening etc, whereas BRC mesh come in standard pattern and size and will result in more wastage.

Hope this helps.

Joker98, that is really informative! Thank you for the information. Can the same 6mm reinforcement bar be used for all my bathroom countertops?

I would go for 6mm and make the rebar spacing smaller...

platinum_12, for advice!

Will certainly follow suggestion from you guys on the rebar part as I am a novice at this.

Really useful and timely advice.

It depends on how the counter top is supported.

If it is supported by 2 stands underneath both ends, then the spacing of the reinforcement bars (or rebar in short) does not have to be that close and can be similar to those in your kitchen counter top. Bars can be placed at mid-depth or closer to the BOTTOM surface. BUT NEVER EXPOSED, you need the concrete to wrap nicely around the bars to protect them from corrosion due to exposure to water.

If they are meant to HANG off the wall, then you should:

1) Drill the bars into the wall and overlap with bars in the counter top
2) Reduce the spacing of the bars
3) Place the bars closer to the UPPER surface of the concrete top

1 & 3 is important for hanging concrete counter tops, especially if some joker (not me as I am joker 98) end up standing on it (like fixing a ceiling leak or light bulb).

This post has been edited by joker98: Apr 12 2014, 09:49 PM

12ft without supporting in between? Wonder it can stand the weight. For 10' my contractor already advice me to put support in between.

You can if you drill bars into the wall and provide support along the long edge. It's like partially hanging off the wall.

Then the 3 points in my previous post will become relevant in this case.

I will have to see how the contractor does the bathroom countertop though.

I have not heard from the contractor to put support in between. He asked me to get the reinforcement material for the kitchen countertop. He only discouraged me from doing away with the tile skirting but I think I will be still doing without the tile skirting - pray the tile alignment is properly done though.

Provided the wall is also a rebar concrete if only red brick it will not stay long, even faster if its cement brick.

Hm, the kitchen was extended and that extended part had red bricks before cementing over it. The extended part will be where the kitchen counter top will be at. The original walls, I am not sure whether it is concrete?

Not too worry bro. It will last.. mine sand brick, with no support at the middle. With all d abuse by me and my wife did to it, it still standing strong for 2 years already.

It can stay long if the starter bars are anchored properly with proper grout (as they are in tension) and the brickwalls done properly. Also the top must be sufficiently thick and the wall surface plaster should be chipped to expose the bricks. A good and experienced contractor should know this.

And it is very important to position the starter bars from the wall along the top face and not bottom face. Even at mid height it is not good enough. If starter bars and reinforcement is placed at the wrong level, then it really won't stay long.

Furthermore, he already has 2 supports at either end and the support along the edge will provide a constant hanging support, which we term cantilever.

This post has been edited by joker98: Apr 14 2014, 08:03 PM

My contractor have difference school of thought, he don't want to build me a kitchen top of 10-11' without middle support as he claim it may crack on the wall, So he build one with middle support he guarantee me chopping cow also won't break. I been standing it few time to install my hood, opening hole for the ducting, and few people standing up during the plaster ceiling installation.

This post has been edited by weikee: Apr 14 2014, 08:42 PM

Having a middle support definitely makes things much stronger.

A kitchen top that is cantilevered will definitely not be suitable for a few people to stand on top. Many other furniture are not suitable for such use too. Not having the middle support opens up opportunities for how the top can be used or other fittings.

Your contractor is being responsible by giving you a very safe solution. The starter bar solution I mentioned is time consuming because you have to drill many holes and anchor each bar properly with grout. Say 1 bar every 4 to 6 inches all along the table top. Many contractors will not do this because it is time consuming. Adding that middle support is easy for them, just prop a few bricks.

But in return you get top with minimal obstruction beneath for your usage. Basically anything that wants to stretch longer, stand higher or hang further will always require more work. Which is why us engineers get a lot of headache from architects, who usually almost want things to float without support in their design. Want narrow but strong, span further with thinner slabs etc.

But what I am trying to tell you is, from the structural design point of view, a partially cantilevered top from a brickwall can work and be done with good experience and decent effort.

This post has been edited by joker98: Apr 14 2014, 08:59 PM

My table top are meant to 3-4 heavy weight standing on it.

Hmm, what happening on top

Well, getting an old school man doing the old school job, sure end up like this(strong and tough)

Hello! I am now back with a question for the concrete countertop.

How is undermount sink fixed to a concrete countertop?