Wednesday, January 4, 2012

Bond Breakers - Number one reason for tile failures in a curbless shower

Bond Breakers - there everywhere.  I bet your breathing some right now.  Dust is our biggest enemy and on a busy job site it is hard to control the amount of dust generated, or when and where it will show up in force.  It might not even not be your dust, or your dirt.  It could have come from the factory or showroom where you purchased your tile.

But one thing is for sure.  If you don't address it, it can come back and bite you.

We went to work yesterday and where going to install a simple pre-slope for a new barrier free shower (no-curb shower) here in Vancouver and when we got onsite the section of the bathroom reserved for me was littered with bond breakers of all kinds.

The worst was dust but equally as bad was the spill out of the cement pour (done by others before our visit).  I was told straight away as I inspected it that it was fine to go ahead and leave it.  I was told it was solid.  Now here is a really good pickle you might find yourself in as a tile guy.

The guy telling me to leave it is the project foreman.  He is also the same guy who did the work in the first place.  I quietly nodded my head and said I might but I just want to check something first.  I went to my tool box, grab my hammer and start "Wacking the floor".  Then I listen. Smaller taps where there is not cement spill out and then light tapping over the cement patch.

I ask the foreman if he cleaned and primed the old cement in the section I was tapping and he said of course not because he had not planned on placing cement there.  The sound here was a hollow sound and a sound you do not want to hear when working with tile and stone.

Then while we where both still in the room I grabbed my chisel and started chipping up the work I was told was fine to leave.  It came out like butter - well most of it.  The stuff I couldn't chip away I left.

Here is a peak at the site prep.

Bond breakers come in many forms.
On this job we had cement, stucco, dust and drywall compound.

Looking at this picture above you can see the multiple bond breakers I chipped up.
Look at some of those big flakes of self levelling concrete.  Now imagine if there is a problem with this instal.  Who would be to blame if the floor failed at this connection point?

Good question and one I wish to never be in again.  Again you say.  Yes again, because ten years ago I trusted someone and we had a failure.  Ten years ago I learned more about bond breakers than I ever thought I could.  Today and every day for the past ten years we have a very simple rule we follow.

You need to be able to strike the surface your bonding tile to with a hammer!  With in reason of course.  Setting a tile backsplash over drywall is not the time to be beating on the wall with a hammer but when your placing a screed a mortar bed from 1 1/4" to 1/2" over 80 year old concrete - that is a great time to bring out the hammer.

A clean floor is so important.
I gained a lot of trust I think from this new foreman.  I had not priced in the extra hour of work it took me to clean up this mess and the foreman himself seem shocked it had happened and helped me clean up the floor.

This project is barrier free shower and there will be no curb.  The exisiting slab or 19th floor of this historic Vancouver Condo already sloped in our favour!  How is that for service.

I chipped away with the hammer and chisel and then a quick sweep, a quick Vac and then a little primer.  For a primer today I used a mix of Mapei's Planicrete AC and water.  I mixed one part AC and three parts water.  We only used a small amount and made the mix in my morning coffee cup.  I used a sponge to apply it.

Priming the old cement for application of a screed
mortar bed.  The primer step is not to seal in dust and no
puddling should be left behind.
There is my morning coffee cup and me priming the floor.  With almost any self level concrete product you will learn (if you read instructions) that a primer coat is needed over plywood or concrete.  If the surface is porous. 


If a surface is porous it will suck out the moisture from the cement.  As the moisture flows and is absorbed by the substrate little pinholes can form.  As the cement product looses liquid quickly it gets weaker since it has to little liquid and or dries to fast.  A primer stops this.  It helps seals the old floor and allows for a slower cure with less absorption of liquid.

This job needed a screed mortar bed from 1/2" to 1 1/4".  Not many mortar can do this.  Mapecem Screed Mortar (Fast Setting) is my favourite and it can even go lower!  That is over a concrete subfloor of course.  Over plywood they recommend 1 3/8".


We will be back at this job tomorrow to tape all the seams on the Denshield and cement board and prep for the application of our waterproofing products.  This job will see a combination of liquid and sheet membranes and we should have the inspectors blessing next week.

On your next project make sure you address bond breakers.  Make sure that all your products are used properly and that the subfloor is structurally sound.

A hammer is a great place to start.  So is a giant wrench.... LOL

That is a real wrench.  My 2" Spanner.
Great for bond breaker detection and laughs on the job site.

If you have any questions on this post please email me at or call me at (604) 506 6792.  If you would like my help building a new curbless shower or barrier free shower with a linear drain I would be happy to help.  We have installed them in Whistler and Gambier Island and love the road trips - so even if your out of town - give us a call.


John Whipple
By Any Design Ltd.
(604) 506 6792

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Remodeling and Home Design