The type of trowel that should be used for a particular tile installation depends on a number of factors, such as the kind of setting material being used and the size and type of tile being installed.
Each installation should be considered individually, but there are general guidelines to follow in choosing the correct type of trowel for a particular installation.
Notched trowels provide a pattern of ribs, which ensure uniform thickness of adhesive material and full contact with the tile after it is compressed. This pushing down of the tile into the adhesive/cement is referred to as “beating in”. The spreading of adhesive using a notched trowel also helps to avoid air pockets.
Tiles with patterned or uneven backs require more adhesive than smaller tiles and tiles with level, smooth backs. Non-absorbent tiles offer no suction, as there are no holes to trap air and cause miniature vacuums. Therefore, non-absorbent tiles require more adhesive to grip the edges as well as the back. For mastic adhesives, we generally use v-notched trowels as this type of adhesive can be readily compressed. However, mastic type adhesives are limited to walls, and light commercial or residential floors.
With sanded and thin-set mortars we generally use a square-notched trowel. This is because the square ribs of mortar break open easily during the beating-in process and give better contact with the tile. If a v-notched trowel were used, the ribs may form flat topped pyramids, leaving gaps between the ribs.
When laying tiles, it is important to cover the whole back surface evenly to ensure a good bond. Relating this to trowel choice, generally, the more uneven the back of the tile or the larger the tile, the larger the notches in the trowel should be. In particularly awkward or difficult instances, it may pay to lay some of your tiles and then remove them to see just how good the coverage is, and if insufficient, it may prove beneficial to apply adhesive to the tile before laying it.
With v-notched trowels, remember to "beat in" the tile i.e. compress it into the adhesive layer/ribs thoroughly. The tile is only immediately in contact with the top of the "mini-mountains" which form the adhesive ribs, as opposed to the immediately larger surface area of square ribs, formed by a square-notched trowel.
Title:
Disabled Toilets
Author:
A.Jeffers
Date Written:
30 Oct 07
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