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Tile Talk April 2021 | Rectified Tiles – Debunked

There’s a small unassuming corner store near my house that has the best New York-style Egg Cream. I think it’s the best, because, I’ve never actually had the real drink – lol .

Anyway, every now and then, the craving comes on strong, and the need to satisfy my uncompromising palate is unrelenting (I’ve tried making my own – disappointment every time).  So, a few weeks ago, I stopped by to order up my favorite fizzy concoction. As I’m about to place my order, my ears perk up and get momentarily distracted, as I hear the distinct grinding sounds of a wet-saw blade cutting through some porcelain tile (yes, I can tell the difference between ceramic and porcelain!).  I slowly sneak around to the back of the house and as I peek over the knee wall, I can see the head mechanic about to start bedding his first row of 6” x 24” rectified porcelain tile.

Fast forward a couple of minutes, with Egg Cream in hand, I find myself talking to both the contractor and the owner about tile body types, best practices, and expectations for rectified tile.  For the most part, this contractor had a lot of experience and knowledge – but I could tell by his body language, that I wasn’t his favorite person – lol!  He was a second-generation tile installer, and I could see that he took a lot of pride in his craft.  But after talking to him for a few minutes, I quickly realized that his expectation of how a rectified tile would perform was not realistic or achievable.  He knew a lot about the tile trade, but his comments on rectified tiles were way off!

This got me thinking.  If a seasoned contractor with years and years of experience is misinformed – how much misinformation is out there in the industry as a whole?  I’m sure you’ve specified rectified tiles for your past projects, but what were the reasons for doing so?  Was it a certain design element that couldn’t be achieved with a traditional pressed tile?  Was it a specific modular layout that needed tight grout joints?

Whatever the reason may be, the next time you specify a rectified tile, avoid these common myths and misconceptions:

You don’t need grout joints

The contractor on this job told me that he was going to eliminate grout joints, and simply butt the tiles tight.  “Since the tiles are rectified, they’re all exactly the same”.

That is incorrect.  Rectified tiles still vary up to 1/32” between tiles of the same production lot.  This means that the installer needs to multiply this maximum variance by 3 and use that number as the grout joint.  In this case, 3/32” would be the smallest (and safest) grout joint.

Rectified porcelain floor and wall tiles
Rectified porcelain floor and wall tiles (1/8” grout joints) | Photo credit: UIP Property Management

Rectified tiles are perfectly flat

This is a common misconception.  Rectified tiles go through a milling process where all 4 sides of the tile are mechanically ground to a certain size.  However, rectified tiles are still the same in composition as traditional porcelain tiles.  And as you recall from my previous blogs, all kiln-fired tiled products have inherent cupping or crowning in the middle of the tile.  This means that you may have a rectified 297 mm x 297 mm tile (+/- 0.5%) which is very precise and predictable in facial dimensions but will still have slight warpage given the way it is “baked.”  Only true gauged tiles and panels are free of warpage and cupping.

Rectified tiles chip easier

Again; incorrect.  I’ve heard this countless times in the field especially when callbacks are related to edge and perimeter chipping.  The truth is most of the time it’s related to shallow grout joints and the top edge of the tile being directly exposed to the elements.  Packing the joints full and flush to the top of the tile is a best practice that should not be overlooked.

Efflorescence is common with rectified porcelain tiles

I think this belief is out there because rectified tiles are mechanically milled on all four sides, thus the assumption that the sides are porous and non-vitreous.  This is a big, fat ‘NO’.  If we were talking about a non-vitreous ceramic tile, there is some truth to that.  In the past, using cementitious grouts (especially in the darker colors) with ceramic tiles that absorb a lot of water could at times impact the way the grout cured.  This would manifest into salt soluble surfacing through the grout in the form of white powder or discoloration of the grout itself.  However, rectified porcelain tiles (just like non-rectified porcelain tiles) absorb very little water and do not absorb more because of the rectification process.  If efflorescence is present, this would have more to do with substrate type, mortar, cleaning of grout, and type of water used.

Rectified tiles cost way more to install

Okay, rectified tiles cost more to install, I’ll give you that – but not way more.  When I was a contractor, if I were to estimate that my mechanic could install 300 SF of a basic 12”x24” tile on a single day, then the yield for this scenario would be 270 SF for a rectified tile.  That’s a 10% reduction in daily yield.  What I see with more frequency is the misinformed understanding that floor prep costs are significantly higher for rectified tiles.  However, the truth is, more and more of the larger tiles on the market are produced to a rectified standard.  So, in actuality, floor prep costs are going up due to the increase in larger and larger tiles – not because of rectification.  Correlation does not equal causation.

luxury tile flooring

Well, there you have it!  Obviously, this is just the tip of the iceberg regarding this topic.  With more and more manufacturers and fabricators creating tiles in a rectified format, I’m sure more misconceptions will grow out of ‘em.  But don’t worry…I’ll stay ahead of it and bring you the truth!

See you in June!