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How to correctly back butter your tiles

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Back buttering is the thin spreading of adhesive on the back of a tile to ensure it correctly bonds to your tiling substrate.


It’s required when fixing large format porcelain tiles with a standard non-pourable adhesive and takes mere seconds but ensures a lasting bond!


To achieve an effective and quick back butter, use a 4mm notched trowel to spread and then flatten the ribs with a flat side of the trowel.


Back buttering is especially important for tiles which are slightly bowed, uncalibrated or where the back of the tile is uneven. British Standards state that 80-100% coverage is needed with large format tiles and 100% for any tiles in wet areas, regardless of size or material.

Wall tiling

If you're tiling uneven walls then you should consider a levelling compound before you attempt any tiling, this will not only make the finished result better but it will make it easier to tile. If you're looking at minor unevenness then back buttering your tiles correctly should ensure proper adhesion between your substrate and tiles.


If we’re getting technical, here’s what the British Standards state for walling tiling.


The amount of adhesive used, and the height of the ribs obtained are governed by the angle at which the trowel is held against the surface. The amount of contact is also dependent on the twisting or sliding of the tiles as they are pressed onto the ribs of adhesive.


It is good practice to remove a tile occasionally as fixing proceeds to check that adequate contact and wetting is being maintained with the adhesive.

7.2.1.5.2 Buttering method
The buttering method can be used for occasional awkward tiling positions, e.g. around openings and restricted areas where a notched trowel cannot be used; where this technique has to be adopted, the adhesive should be spread evenly over the whole of the back of each dry tile with a trowel.

The bed thickness should be slightly greater than the final thickness required so that when each tile is pressed or tapped firmly into position the correct thickness is achieved. The thickness should not be greater than the maximum recommended by the manufacturer of the adhesive. Care should be taken to ensure that as far as possible no voids are left behind the tiles.
7.2.1.5.3 Notched trowelling and buttering method
The notched trowelling and buttering method combines 7.2.1.5.1 and 7.2.1.5.2 and should be used for fixing large tiles and tiles with ribbed, deep keyed or heavy buttoned back profiles.

A thin coating of adhesive buttered over the backs should fill the deep keys before placing the tiles in position on the combed adhesive bed. There should be no significant increase in the bed thickness. This bedding method aims to achieve a solid bed but, in practice, a number of small voids are inevitable.
Floor tiling
Similarly to wall tiling, they have specific requirements for floor tiling that should be followed for a professional and lasting finish.
Section 7.2.1.1 Bedding in adhesives (general) states:
The tiles should be thoroughly bedded in the adhesive so that as far as possible no voids remain beneath the tiles, i.e. solid bed fixed. Any voids under the tiles are vulnerable to damage under loads and impacts, whilst in exterior situations, water can accumulate in voids so that damage can occur on freezing.
(BS 5385: Part 3: 2014) 7.2.1.2.1 Notched trowelling and buttering method
When floor tiles are fixed using normal cementitious adhesives the adhesive should be applied to the sub-floor as well as to the back of the tile to ensure solid bed fixing. The mixed adhesive should be applied to the sub-floor using a trowel as a floated coat, pressing the adhesive into the surface before combing through with a notched trowel as a spreading gauge to provide a uniform ribbed adhesive bed.

The backs of the dry tiles should be buttered with the adhesive to coat the surface and to fill flush any back profile or key to form a contact layer before placing the tile on the ribbed adhesive bed. Each tile should then be pressed or tapped down with a rubber mallet firmly into position. The adhesive should preferably be trowelled out as straight ribs and tiles should be pressed into the ribbed adhesive bed whilst the ribs are still wet and workable, i.e. within the “open time” of the spread adhesive. If pourable floor tile adhesives are used it is possible to fix the tiles in a solid bed of adhesive without having to butter the backs of the tiles. If the floor tile has a deep back profile then solid bedding might not be achieved unless the back of the tile is buttered.
Checking in
Finally, a freshly fixed tile should be lifted to check that the size of notched trowel and the bedding technique used results in no voids being left beneath the tile. When bedding is found to be incomplete either increase the angle between the trowel and sub-floor when combing out the adhesive ribs or use a trowel with larger notches. This check should be carried out occasionally during the fixing of the floor tiles to ensure solid bedding is consistently maintained.
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