QUESTIONQuick question, we are doing another hotel and making sure we follow all appropriate guidelines. Looking at some of your articles online I was trying to determine the recommended soft joint application that's within TCNA guidelines and it's a bit confusing.
Attached is a layout with 23"x47" tile installed on 1/3 offset. I assume we would follow the grout lines as close as we could to TCNA recommended distances. The Architect is asking that we cut through all of the tile with a straight line as illustrated in the attached drawing. This would obviously look terrible and defeats the purpose of using large format tiles because they are all going to be cut into large and small pieces? Thoughts?
ANSWERThe TCNA EJ171 now allows for zipper or sawtooth generic movement joints in tile installations, where you follow the grout joints within the tile assembly, not into the mortar bed.
It is not uncommon for the movement joints go straight across, which would be more practical if the movement joint extends into the mortar bed if this is a mortar bed installation.
The joints are suppose to have a compressible closed cell back up strip with an ASTM C920 Traffic Grade sealant. It should be tooled to achieve a slight recess so the foot traffic doesn’t touch the sealant. They should be installed very 20 to 25 feet in each direction for interior applications that are not subject to direct sunlight. Exterior and Interior applications subject to direct sunlight are to be placed every 8 to 12 feet in each direction.
Be sure to include movement joints at all the perimeters, change of plans, and where you are tiling up to restraining surfaces. You need at least a ¼” wide joint. It can be left open if there is a tile base going over it. Otherwise you need to install the backup strip with the ASTM C920 sealant over it.
15 thoughts on “How Should Movement Joints (expansion joints) be Installed in Tile Installations?”
We have a large 20,000sf kitchen we will be installing with Daltile Quarry Que Tread 6”x6”x1/2” tiles, see below in yellow. The architect is asking us what our recommendation would be for expansion joints, what are your thoughts for this large of an area? Your help is much appreciated.
Expansion joints is a type of a movement joint as described in TCNA Handbook detail EJ171.
If you are floating a mortar bed over the substrate to establish a slope to drain for the waterproof membrane to go over and for the tile to bond directly to the membrane, then the movement joints need to be continuous from the structural slab up through the tile. The membrane then needs to be looped into the movement joints to be continuous. A closed cell compressible back up strip is inserted with an ASTM C920 Traffic grade sealant installed over it. The sealant needs to be up to ½” thick and at least ¼” thick. The sealant should be tooled to a slight concave finish so that foot traffic does not come into contact with it to prevent it from getting excessively dirty.
Movement joints on interior applications should be installed every 20 to 25 feet in each direction. You need to have movement joints that are ¼” wide at all perimeters of the tile areas and where it changes plane. Normally if you have a shoe base then you can leave the movement joints open and place the base over it so you can’t see it. But since this is a commercial kitchen, then I would fill all perimeter joints with the ASTM C920 sealant (silicone or polyurethane) as a water stop to help prevent water getting inside the walls. Your waterproof membrane should be going up the wall at least 6” as you know they normally use water hoses to wash down the tile during cleaning at the end of the night.
Since cracks tend to occur at outside corners of walls and doorways. I would lay your movement joints out to be at those locations even if you have to add additional movement joints.
If the tile is being installed in a running bond pattern (staggard) you can install them in a zipper or saw tooth pattern following the grout joint if you are installer over a concrete substrate. Otherwise you should lay them out in a lineal geometric pattern.
I assume you will be grouting it with an epoxy grout that is chemical resistant.
We have another question about expansion joints.
When honoring the joint up through the tile does it have to be exactly on top of the expansion or can it be off set by an inch? We have come across an instance where the existing joint is around the 2” mark of a 6” tile. The architect was wondering if we could split the tile at 3” having the soft joint an inch from the existing expansion joint.
Per TCNA EJ171 you have to honor any underlying control or expansion joints with a movement joint that is exactly over the underlying joint.
If you bridged the underlying movement joint then when that joint moves it would likely cause the tile above to crack since the tile is bonded to both sides of the control joint.
Some crack isolation membrane companies will allow you to isolate the underlying control joint (not a true structural expansion joint that can move vertically) with their crack isolation membrane and then install the movement joints on either side of the tile that is bridging the control joint. The membrane below has to be at least 3 times the width of the tile so that the entire tile is bonded to the membrane and isolated from the concrete substrate. This is also somewhat consistent with TCNA partial movement joint detail F125-partial-2022.
On a project I am doing there is about 500 sf of 24x48x3/8” black porcelain tile to install at a 3 story high stairwell wall. Above the entire stairwell wall is a skylight approximately 10’x20’. It is above the upper two story’s of the stairwell. Because of the direct sun light I am concerned about grout joint size and movement joints.
I’ve consulted the tile supplier and the thinset manufacturer and they both recommended a 3/16” grout joint, but, obviously, say to follow TCNA guidelines. In reviewing the TCNA regarding movement and expansion joint, it gives a lot of information for interior areas without direct sun light.
However, the information is very limited for areas have direct sunlight. From what I read, the only guideline is the movement joints have to be a minimum of 1/8”, there is a 2:1 ratio for width to depth and the movement/soft joints have to be between 8-12 feet apart. Am I reading this correctly? Are there any other guidelines I’m not aware of? Would you recommend mechanical fasteners above a certain height.
We are planning to float the wall, use a primer recommended by our thinset supplier and thinset over with an S2 thinset. We will have a soft joint around the perimeter. I’m looking for advice as to grout joint size ( the designer would like the grout joint to be 1/8” or less) and are there guidelines in regard to width and spacing of movement joints?
In ANSI A108.02 where they talk about off-set tiles of 50% vs 33%, they do recommend a 3/16” grout joint to minimize potential lippage with staggered layout on tiles with one edge 15” or larger.
If the warpage isn’t bad and you are installing over a plumb substrate you should be able to set with 1/8” wide grout joints and not get more than 1/32” lippage.
For a 1cm thick porcelain tile you don’t need to mechanically attach unless you are doing soffits. Using an ANSI A118.15 thinset like Laticrete 254 Platinum and getting full thinset contact between the back of the tile and substrate it won’t go anywhere. Assuming you have a good structurally sound substrate to go over.
Movement joints where tile gets full sunlight from windows EJ171 suggests have movement joints every 8 to 12 feet. Technically at 12’ they want a 3/8” wide movement joint and a ¼” wide at 8’. If you place them every 4’ then you can have a 1/8” movement joint. These are only recommendations. Chances are if you do the math in terms of coefficient of expansion of the various materials you can problem do a 1/8” wide movement joint at 8’ or 12’. With that large of tile you might consider caulking all of the grout joints with an ASTM C920 non-sag silicone. It will increase the strength of the attachment to the wall and give you maximum movement mitigation.
With a 5/16” thick tile you aren’t going to meet the 2:1 ration width to depth. The sealant joint manufacturer wants at least ¼ thick sealant. You are suppose to have bond breaking tape in the grout joint so you have only two point contact, but with a 1/8” joint on a wall it is problematic. I would just fill the joint with sealant so it does bond to the substrate that increases the strength and resiliency of your attachment.
Hi, can you reuse 24”x48”x3/8” porcelain tile with thin set/mortar residuals for exterior wall cladding?
In theory porcelain tiles can be reused. If the thinset mortar is tenacious attached to the back of the tile you can carefully grind off some of it. Although it might not be practical to spend the time and effort to grind the tile.
You have to make sure you have the depth to re-install the tile as the thinset makes it thicker.
I will be tiling over a recently poured patio which is L shaped. The longer part of the L is 13′ x 40′ and has 3 control joints pressed into it and then one more control joint between the smaller part of the L, which is 13′ x 12′. I will be using Ditra uncoupling membrane under the tile. I have already filled the control joints in the concrete with polyethene to keep the thinset out of them. is the proper way to do a saw-tooth soft joint in the tile gaps over each control joint below it or could I skip one or two soft joints over the control joints below? this is outdoor and will have direct sun hitting the tile during the day, no freezing temps though.
According to the Ditra Handbook you can use it as a cleavage membrane an crack isolation membrane over control joints without honoring the control joints. It will isolate the tile installation from the concrete control joints as long as there is only in-plane movements. It will not work for out of plane structural movements. Check with Schluter’s handbook for verification of usage and treatment.
You still need to have movement joints within the tile work and at all perimeters and changes in plane. According to the Schluter Handbook, unlike other types of crack isolation membranes you don’t need to line the movement joints in the tile work over the concrete control joints when using the Ditra uncoupling membrane.
The saw-tooth or zipper movement joint is only for generic movement joint applications. That is where the movement joint is only within the tile and not within the underlying substrate. So you should be able to put the zipper joints where you want. I would put a movement joint in the tile area where it transitions in the L shape from one direction to the other as those areas tend to have stress from differential shrinkage within the mortar.
The exterior floor has to be sloped to the drain at the waterproof membrane. Ditra can be made to be a waterproof membrane if you follow Schluter’s directions. We have seen problems with Ditra in exterior applications that are subjected to moisture from rain or maintenance. It tends to collect residual moisture in the cavities of the Ditra that can then subject the tile to excessive moisture as it never dries out in those conditions.
Thanks for the quick reply. I had have gone back and forth on whether or not to seal the ditra seams. the patio will be partially exposed to rain. I had thought about the water that makes it through the seams of the ditra collecting in the catacombs at the bottom layer. I thought it would eventually soak into the mortar and then into the concrete patio. and then thought those same seems would allow for evaporation to take place of any accumulated water in the ditra. I was leaning towards not sealing the seams for that reason. I was going to use a matched color caulk around the entire perimeter of the ditra which would seal those exposed edges of the ditra from rain water.
Most things I read about sealing the ditra seams was to do with preventing water from continuing to a floor beneath it, but with the outdoor patio, that is not a concern.
so if I seal the perimeter edges of the ditra and the seams between the ditra, it would be somewhat of a water resistant platform. and maybe thats the best way to go after reading your comment about the trapped moisture within the ditra.
Using Ditra as a waterproof membrane you have to seal the seams. You not only are concerned about water from the surface migrating into the tile assembly and below into the slab, but you are concerned about the moisture coming up from the slab. If you have a vapor retarder under the slab and up along the sides of the slab then you are preventing water from getting in and out. Leaving the seam open on the ditra will not relive the residual moisture trapped in their plastic matrix.
We have forensically invested gated several exterior stone tile installations in wetter portions of the and several in drier areas over Ditra and my conclusion is it should not be used in outdoor applications. Reading the Schluter info they seem to be reluctant to recommend it for outdoor use. I would go with a liquid applied waterproof membrane that meets ANSI A118.10 and A118.12 for crack isolation. It is easier to install. More forgiving. And it doesn’t get residual moisture as long as you have an adequate slope and drainage.
Donato, I do appreciate your insight and advice. I’m kind of pressed at this point since I’ve already purchased the ditra and sending it
back would be cost prohibitive, I will plan on extending the the half roof over the patio, creating a full roof and at least prevent any direct rainfall onto the tile floor below. there is a vapor barrier below the slab and into the footer around it. so it does have protection from moisture leaching into the concrete from below. its on a slope so there is never any standing water. and the Florida sun keeps things pretty dry during the day. hopefully reducing the majority of rain on the tile will keep things somewhat normal and I won’t regret moving forward with the ditra.
I have a project where elevated litedeck insulated concrete floors are adjacent to wood framed floor systems, L720+., and a large format tile (24×48 most likely) is desired over the whole area. My supplier says a control joint where the systems meet with Ditra over the whole area would eliminate the need for visible control joints, is this a reliable application?
If you read the Schluter Ditra data sheet it says you have to install movement joints per TCNA EJ171.
At all transitions of plane and transitions in other materials or substrates much have a movement joint to mitigate the anticipated differential movements and stresses. In addition to that every 8 to 12 on exterior applications you need to have movement joints within the tile assembly from the Ditra on up.