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Top Five Tips for Installing Movement Joints

Video Transcript

Welcome to Custom Technical University and our Top 5 Tips for Installing Movement Joints in tile assemblies.

Did you know the number one cause of tile failure is a lack of movement joints?  If you’d like to avoid tenting, cracking and broken tile on your projects, learn all you can about movement joints.

Construction materials will experience motion and sometimes they move a lot or very quickly due to factors like thermal cycling or deflection.

Entire buildings expand and contract, concrete slabs move due to live and dead loads, they sag or creep over time, and even well bonded tile can crack and come right off the surface. 

Tip #1.  Accommodate Expected Movement

Tile assemblies should be designed to withstand dynamic forces by moving along with them.  And, in certain conditions like direct sun or freezing and thawing, the tiles themselves are actually in motion. 

In a 90-foot span of dark tile, up to 8 inches of movement can take place on a hot sunny day! 

Soft, flexible joints within the tile assembly help to accommodate inevitable expansion and contraction. Movement joint fillers will absorb compression during expansion, whereas tile and grout are not designed to compress. 

Flexible sealants return to their original size after compression from tile expansion, over and over, or day in and day out; this is referred to as cycling.

Throughout this video, we will be turning to Detail EJ171 – Movement Joint Guidelines in the Tile Council of North America’s Handbook for specific information.  

EJ171 begins: “Perimeter and field movement joints within a tile installation areessential and required.” That phrase is the single most important takeaway on this topic.  These soft movement joints are installed at changes of plane and set intervals based on project conditions.  Joints in the slab are also honored when carried up through the tile assembly.   So give your tile these breaks – or they will break later on their own. 

Tip #2. Understand the Joints in a concrete Slab

There are many types of joints in concrete; some are designed to move, others may or may not move in the future. 

TCNA recognizes and lists the most common types.  You can differentiate and treat them based on their function.

  • A construction or cold joint is formed between placements of concrete during the pour.
  • Control, contraction or saw cut joints are added during or shortly after placement to help regulate expected cracking during curing of the slab.
  • Expansion joints are created at adjoining parts of a structure to accommodate anticipated expansion beyond contraction. 
  • Isolation joints are located at changes of plane, such as columns, where vertical movement is expected.

Joints that are designed to move out of plane should NEVER be covered with ANY type of floor covering

 

Tip #3. Carry the Joints through the Tile Work

According to TCNA, all of these joints are considered active and must be carried through the tile assembly. 

That means creating soft, flexible joints at the same width as those in the slab directly below.  Typically, they’ll directly follow the cold joint or expansion joint in the concrete

For joints that are considered static by the project design team, such as a control joint, material manufacturers may recommend treatment with an ANSI A118.12 crack isolation membrane.

In some cases, a saw-tooth pattern following a joint in parallel may be allowed along with soft joints.

Tip #4. Follow TCNA Detail EJ171 Recommendations

According to these guidelines, movement joint location and details are the responsibility of the design professional or engineer.  (If they have not been provided in the drawings, you’ll need to submit an RFI, or Request for Information.)

Joint placement is based on dynamic elements such as joints in the slab.  Variables like frequency and width depend on location and climatic conditions.

These requirements are designed to manage expected movement based on thermal cycling and deflection. 

Here are the default placements in each direction:

  • For interior spaces, the maximum allowance is every 25-feet.
    • When interiors are exposed to direct sunlight or moisture, the (requirement doubles;) spacing comes down to every 12-feet.
    • For an above-ground slab, which can expect higher levels of deflection, the maximum spacing is also 12-feet.    

Due to anticipated thermal expansion and water exposure, exterior applications require movement joints every 8 – 12-feet depending on materials and conditions. 

Perimeter joints are always required at walls, changes of plane, or any restraining surface, including other floor coverings, especially over wood framed construction.

Joint widths are calculated with a formula based on the linear thermal expansion of the tile. Your design team can refer to EJ171 for the mathematical calculations. 

  • For exteriors, the minimum width is 3/8-inch.
  • Some interior joints can go as narrow at 1/8-inch, but ¼” is preferred and is required for perimeters or areas exposed to sun or moisture.

 

Tip #5. Install soft joints properly

Movement joints can be subtle and complement the tile design – just use a sealant that is color-matched to your grout. 

And, the joint filler needs to remain permanently flexible, so choose a 100% solids silicone sealant that complies with ASTM C920.

On commercial projects, the minimum joint width is typically  no less than a quarter of an inch, and the ratio of width to depth is 2:1.  ASTM C1193 details how the joint should be properly filled. 

One very critical aspect of installation is that joints must be completely clear of mortars and grouts prior to using sealant.  It’s helpful to tape the top of the tile on either side of the joint for easy clean up. 

Place a compressible back up strip in the bottom of the joint.  Then, add the sealant above it.  The sealant should adhere to the sides of the adjacent tiles but not the backer rod or substrate.  It is also acceptable to use a pre-formed movement joint in lieu of using sealant.

Placement of movement joints is crucially important for successful tile installations and to maintain a good reputation for our industry. 

They are also a requirement to qualify for any CUSTOM system Warranty.  I urge you to read and refer back to TCNA EJ171 for full information on installing movement joints. 

 

If you'd like to know more about protecting your next project, please visit our website—custombuildingproducts.com—or give us a call. And be sure to “like” our video, share it and subscribe for the latest tips on tile installation.

Thanks again for joining us at Custom Technical University. See you at our next edition of CUSTOM's Top 5 Tips!

 

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