Tile Underlayment: Yes or No?

Failure to install underlayment before tiling can spell disaster for your tile installation.

Having no idea of underlayment as a strong, solid, and supportive base for tiles: is a common issue, our clients face.

“Please come to our place to help us with waterproofing and tiling. It is quite urgent,” said one of our repeated clients in North Shore. 

HOWEVER, when our tiler came, the floor was not ready for him to do waterproofing or tiling as the floor is made of wood. It requires an Underlayment Layer before waterproofing and tiling.

Our client had no idea of that. Here are some photos of the floor:

 So, What is an Underlayment?

A tile floor includes three layers: the subfloor, the underlayment, and the tile you walk on. Underlayment is the solid stabilizing layer, laid directly below the tile adhesive and the tiles. If you fail to install the underlayment, it can spell disaster for your tile installation.

Types of tile underlayment are various, but all are served to level out uneven spots in a subfloor and create a solid and stabilizing layer, preventing the floor from flexing underfoot. In many cases, without the support of underlayment, a slight movement of a subfloor can cause grout lines to crumble and tiles to crack. 

When do we need underlayment for tiling?

You need to install underlayment before tiling in various cases.

But it will fall into three main cases:

A wooden subfloor: tiles cannot be laid directly onto wood (plywood, pressboard, hardwood, etc.). Wood is likely to shrink or expand and warp or swell due to temperature and humidity changes. All this movement is too much for tiles as it can cause tiles to pop off or crack. 

A concrete slab: tiles can be laid on concrete slabs. However, this is not the best and safest choice as concrete slabs can absorb water from outside. That moisture can “wriggle” into the thinset and tiles, causing structural problems to your floor or promoting bacterial growth. So, an underlayment with a waterproofing function is recommended. Concrete also takes a long time to cure, much longer than you think. A slab that was poured 15 years ago could keep curing and is likely to shrink and crack. If so, these cracks then transfer to the tile, causing the tile and grout to crack too.

An old floor: Old flooring can cause old problems such as cracks, creaks, leaks, or unevenness, which then transfer to the tiles. 

What are options of tile underlayment?

Your tile underlayment options are classified into three main categories, each suited for different tiling situations:

Sheet-type (backer board or cement board): This is the most preferred by professional tilers when installing ceramic or porcelain tiles. Its reasonable price and efficiency make it the most popular underlayment option. However, it is quite heavy and not waterproof. It also requires a skillful person to cut it as it is quite tricky.

Extruded Polystyrene (EPS): is another option with pros: very light, easy to work, insulating, and 100% waterproofing. However, it is quite expensive. 

Flexible tile mat: A plastic mat with a raised pattern, backed by a synthetic fiber is the latest underlayment option, offering many more features than the other two. It is thin, light, easy to cut, easy to transport and 100% waterproofing. Besides this option also offers some added features of crack isolation or integrated heating or insulation.

You can save money by excluding unnecessary stages. However, we would like to recommend that you should get consultation from your tiler on installing underlayment or not. Please talk with Cozy Tiling at https://www.cozytiling.co.nz, if you wonder about any tiling issues. We hope that any time you search “Tiler near me”, Cozy Tiling is the one you find.