Sealing Qcon or similar to prevent water absorption

[pferdy62]

Does anyone have any experience with needing to seal Qcon bricks prior to applying render and tiles in wet areas like the bathroom to stop them absorbing water?

 

Our architect says that Qcon (and similar products) will absorb water and this will create problems.  I thought that a properly rendered and tiled wall would be almost totally waterproof and that no water would soak through to the bricks.

[Denim]

Our house is all Qcon except the bathroom which was done with red bricks for this very reason. Probably the best thing you can do is a lot of internet research to see what products are out there suitable for your purpose. Once you find something see if it is available in Thailand.

I have certainly seen various types of sealant in home pro etc but which one would be best for Qcon I couldn't say.

[johng]

Water will find its way through the render and tiles..

One way to be sure of no leaks would be to use some of the 2 part epoxy roof sealer to line (tank) the wet room/bathroom, not sure if it can be tiled over though.

[David B in Thailand]

The OP might take what his architect said with a grain of salt. What ever builders merchants store supplied the AAC block in Thailand to build his home can get on the telephone and have a technical advisor come to his home building site at no charge to instruct his workers how to properly install and render Q-Con or Diamond Blocks and Lintels. I have more than one bathroom built with AAC blocks in Buriram. Each bathroom has tile to the ceiling. A key to success is using the correct Weber or Lanko tile adhesive. Shower tile takes a different tile adhesive than the dry room in your bathroom.  There are  written instructions in Thai and English available for q-Con and Diamond AAC Blocks, Wall panels and lintels in Thailand. There are dozens of Thailand videos of the proper installation of both brands of AAC blocks on youtube.  In my personal experience they must wet the block wall the night before rendering. Then the morning of rendering the wall they wet it once again. Only us the proper wall render, no matter which company. TPI makes two grades of AAC block wall render. Weber, Lanko, Diamond, SCG all market AAC wall block render. The technical advisors that I have met with SCG, Diamond, Weber, Lanko and Q-Con spoke English. Lanko 107 will fix cracks in AAC wall blocks better than any product I have ever found in Thailand. 

[pferdy62]

Thanks everyone for your advice.  I think a trip down to the local SCG building shop is in order to talk to their people about this.

[sometimewoodworker]

On 23/07/2017 at 9:14 AM, Denim said:

Our house is all Qcon except the bathroom which was done with red bricks for this very reason. Probably the best thing you can do is a lot of internet research to see what products are out there suitable for your purpose. Once you find something see if it is available in Thailand.

I have certainly seen various types of sealant in home pro etc but which one would be best for Qcon I couldn't say.

Not such a great idea.

 

Water absorbed by AAC And red brick

 

this is test is not done in Thailand but the results are the same here.

 

AAC: blocks poor at absorbing water

Brick: quite good at absorbing water.

 

the materials under will waterproof your walls and floor

[claynlr]

Jerome-At what stage to apply...before or after render?  If after render, tile adheres OK?

[sometimewoodworker]

I would probably apply it before the render. But I'm just guessing, I think that either could work. As a last resort try reading the instructions  you will have to give it a few days to completely cure before putting anything over it.

[eyecatcher]

I am a bit curious why the op would be concerned about water seeping inside a qcon wall?

The fact is a wet area in a bathroom should be tiled regardless of what brick/block/wallboard the wall is constructed of.

 

One of the very first experiments I did as a building student was to test absorption rates on facing bricks, engineering bricks, pfa blocks, celcon blocks (the forerunner of qcon i would say), thermal blocks...(and a few vids on youtube also) but the worst one for soaking up damp and keeping it there are the bricks.

 

The aerated blocks are 50% air voids so its more difficult to absorb the same amount of water.

 

I have  q cons on my external wall, one of which is a shower wall. I never had any qualms about water penetration and even if it does, where does it go? a leaking pipe may be a concern but day to day shower use on that tiled wall shouldnt be.

 

That aside, if you are using qcons you should use the aac block render cement, its designed for use with aac, to help against driving rain, it has more lime content and more "stick". nyou cannot or should not use standard render/sand

 

Another way to help if you are concerned is to use bigger porcelain tiles. a 300 or 400 high tile is likely to be 10mm thick so keep the joints very tight and any damp penetration should not be of any concern.

 

I would advise however if you have a shower partition/screen wall then build it from brick or block. It will not be supported on the open side so the density of brick will be an advantage if you happen to slip against it when you are *issed  

[pferdy62]

To reply to Eyecather, the reason for the post is in response to our Thai architect's comments the the bathroom walls should be built using red bricks and not Qcon because of the water absorption problem.  I would have expected that with quality rendering and tiling that it should be almost impossible for water to get through to the bricks.

 

Based on earlier posts, I will coat the Qcons with a sealer, then render and tile and I am confident that this should keep everyone involved in this project happy.

[canopy]

It's bizarre to hear people won't use q-con in bathrooms due to dampness yet happily use them on exterior walls that take driving rain.

 

It's best to ask SCG any questions about their products. They will tell you exactly the right way to do it. They even answer emails in English.

 

[sometimewoodworker]

On 27/07/2017 at 6:56 PM, pferdy62 said:

To reply to Eyecather, the reason for the post is in response to our Thai architect's comments the the bathroom walls should be built using red bricks and not Qcon because of the water absorption problem.  I would have expected that with quality rendering and tiling that it should be almost impossible for water to get through to the bricks.

 

Based on earlier posts, I will coat the Qcons with a sealer, then render and tile and I am confident that this should keep everyone involved in this project happy.

Your report of your Thai "architect's" comments would suggest that while he could be an OK designer he clearly has no understanding of the properties of the materials he is designing to be used.