Students learning how to perform a mortar bed installation in a classroom setting.


Contrary to what many industry people will tell you, a traditional “mud-set” installation is not a lost art. While it is true that this proven method has decreased in popularity for a number of reasons, there are still plenty of times when it is practical and often necessary to implement a mud-set installation. This is why it makes sense to continue to train installers to learn the craft of mud-setting in a variety of situations.

A tile is used to find the desired height before screeding the mortar bed to a level finish.

It is important to note that significant confusion exists at times when referring to a mud-set tile job. I am referring to the mixing of Portland sand and cement, with hydrated lime over a cleavage membrane with reinforcing wire mesh. This can be done on both floors and walls, in either a wet set method (fresh mortar bed) or on a cured cement mortar bed with a dry set (no latex) or latex modified mortar being used as the adhesive. Many people refer to thinset or cement adhesive as mud. This is not what I am talking about in this instance.

In a survey we sent out a few years back, only about 10-percent of the respondents were performing traditional mud-set installations on floors and walls on a regular basis. The development of Wonderboard and other cementitious backerboards, along with several other types of approved backerboards for wet and dry areas for ceramic tile on walls and floors, have changed the course of the industry in this fashion. In the past few years, methods to successfully install ceramic tile over poured gypsum underlayments and cementitious self-leveling underlayments has replaced traditional mortar beds in many instances as well.

It is simply less costly in both materials and labor to install ceramic tile over backerboards and other approved substrates in our trade, such as plywood, in dry areas.

Learning how to perform traditional mortar bed installations will be part of the requirements for Ceramic Tile Certification with the Ceramic Tile Education Foundation.

In addition, a mud-set installation must be set at a minimum of 3/4” in a residential application over an approved wood substrate, with 1-1/4” minimum height requirements in all other specifications. This can create transition difficulties at times when matching other floorcovering products on the floor.

Despite this trend in reduced mud-set installations, when we asked respondents if they still installed some projects in a mud bed, a resounding majority indicated that they did. They cited numerous reasons for doing so. The majority of respondents cited method F111 for installation over a concrete subfloor in the Tile Council of America Handbook as their guide for when and how to perform mud-set tile work. This method involves the application of a cleavage membrane (15-lb. roofing felt) directly to the concrete slab to allow drying time of the mortar bed.

Another area of installation where mortar bed installation is prevalent is the shower floor or receptacle. Despite new technological advancements that make this application easier for many, a significant amount of contractors are installing mortar beds in this fashion. The NTCA and Ceramic Tile Education Foundation still teach traditional mortar bed shower receptacle installation. In fact, the CTEF Certification Program, being launched in 2008, plans to include properly installing a mortar bed as part of its Level Three requirements.

It is important to note that in some geographic areas in the United States, mud-set or mortar bed installations are still extremely popular on both floors and walls. In other regions, at least residentially, it is becoming less and less common. It is a tried-and-true method when installed properly, and creates an outstanding substrate for ceramic tile installations. It is not a lost art, it is a specialized craft, and it is still relevant in our trade today.